Publikationen der Professur für Hydrologie

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Journal Articles

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2020

• Bork, M., Lange, J., Graf-Rosenfellner, M., Lang, F.
  Controls of fluorescent tracer retention by soils and sediments
  2020 Hydrol. Earth Syst. Sci., Copernicus Publications, volume: 24, issue: 2, pages: 977 - 989
• Ries, F., Kirn, L., Weiler, M.
  Experimentelle Untersuchung der Abflussbildung bei Starkregen
  2020 Hydrologie & Wasserbewirtschaftung, volume: 64, issue: 5, pages: 221 - 236
• Fernández-Pascual, E., Bork, M., Hensen, B., Lange, J.
  Hydrological tracers for assessing transport and dissipation processes of pesticides in a model constructed wetland system
  2020 Hydrol. Earth Syst. Sci., Copernicus Publications, volume: 24, issue: 1, pages: 41 - 60
• Hellwig, J., de Graaf, I. E. M., Weiler, M., Stahl, K.
  Large-Scale Assessment of Delayed Groundwater Responses to Drought
  2020 Water Resources Research, volume: 56, issue: 2
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  Abstract

  Abstract Groundwater is a vital resource for freshwater supply during extended droughts and also a key storage governing drought propagation through the hydrological cycle. Current drought monitoring lacks large-scale estimates of groundwater droughts, but progress of country-to-global-scale models in the last years suggests that they could now be valuable tools to study and monitor water availability during extended droughts. As a prerequisite the models would need to be able to depict the diverse groundwater response to precipitation well enough to distinguish spatial differences. Here we developed a high-resolution transient groundwater model for Germany and tested its ability for representing the groundwater system dynamics with a focus on droughts. Validation of model results against streamflow-separated baseflow and groundwater head observation confirmed the model's ability to generally represent the groundwater head dynamics over 40 years with lower model performance in mountainous regions where model resolution was too low to capture local valley aquifers. The precipitation accumulation time that has the highest correlation with groundwater anomalies increases with hydraulic conductivity and specific yield from few months in the Central German Uplands to several years in the porous aquifers of northern Germany. Corresponding to these differences, distinct meteorological drought types led to different simulated groundwater reactions across Germany. Given the importance of groundwater as a resource, large-scale groundwater models are important tools for future studies on drought propagation as well as groundwater drought under climate change.
• Ries, F., Kirn, L., Weiler, M.
  Runoff reaction from extreme rainfall events on natural hillslopes: a data set from 132 large-scale sprinkling experiments in south-western Germany
  2020 Earth Syst. Sci. Data, Copernicus Publications, volume: 12, issue: 1, pages: 245 - 255
• Weiler, M.
  Vorwort
  2020 Hydrologie & Wasserbewirtschaftung, volume: 64, issue: 5, page: 220

2019

• Joseph, J., Külls, C., Arend, M., Schaub, M., Hagedorn, F., Gessler, A., Weiler, M.
  Application of a laser-based spectrometer for continuous in situ measurements of stable isotopes of soil CO2 in calcareous and acidic soils
  2019 SOIL, volume: 5, issue: 1, pages: 49 - 62
• Herbstritt, B., Gralher, B., Weiler, M.
  Continuous, near-real-time observations of water stable isotope ratios during rainfall and throughfall events
  2019 Hydrol. Earth Syst. Sci., Copernicus Publications, volume: 23, issue: 7, pages: 3007 - 3019
• Weiler, M., Schuetz, T., Schaffitel, A., Koelbing, M., Steinbrich, A., Brendt, T.
  Der naturnahe Wasserhaushalt als Leitbild in der Siedlungswasserbewirtschaftung
  2019 , volume: 5
• Gottselig, N., Sohrt, J., Uhlig, D., Nischwitz, V., Weiler, M., Amelung, W.
  Groundwater controls on colloidal transport in forest stream waters
  2019 Science of The Total Environment, page: 134638
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  Abstract

  Biogeochemical changes of whole catchments may, at least in part, be deduced from changes in stream water composition. We hypothesized that there are seasonal variations of natural nanoparticles (NNP; 1–100 nm) and fine colloids (<300 nm) in stream water, which differ in origin depending on catchment inflow parameters. To test this hypothesis, we assessed the annual dynamics of the elemental composition of NNP and fine colloids in multiple water compartments, namely in stream water, above and below canopy precipitation, groundwater and lateral subsurface flow from the Conventwald catchment, Germany. In doing so, we monitored meteorological and hydrological parameters, total element loads, and analyzed element concentrations of org C, Al, Si, P, Ca, Mn and Fe by Asymmetric Flow Field Flow Fractionation (AF4). The results showed that colloid element concentrations were < 5 µmol/L. Up to an average of 55% (Fe) of total element concentrations were not truly dissolved but bound to NNP and fine colloids. The colloid patterns showed seasonal variability with highest loads in winter. The presence of groundwater-derived colloidal Ca in stream water showed that groundwater mainly fed the streams throughout the whole year. Overall, the results showed that different water compartments vary in the NNP and fine colloidal composition making them a suitable tool to identify the streams NNP and fine colloid sources. Given the completeness of the dataset with respect to NNP and fine colloids in multiple water compartments of a single forest watershed this study adds to the hitherto underexplored role of NNP and fine colloids in natural forest watersheds.
• Sprenger, M., Stumpp, C., Weiler, M.
  How old is the water from the tree canopy to groundwater?
  2019 Eos, volume: 100
• Ulrich, U., Lange, J., Pfannerstill, M., Loose, L., Fohrer, N.
  Hydrological tracers, the herbicide metazachlor and its transformation products in a retention pond during transient flow conditions
  2019 Environmental Science and Pollution Research, volume: 26, issue: 26, pages: 26706 - 26720
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  Abstract

  Since decades, surface water bodies have been exposed to pesticides from agriculture. In many places, retention systems are regarded as an important mitigation strategy to lower pesticide pollution. Hence, the processes governing the transport of pesticides in and through a retention system have to be understood to achieve sufficient pesticide attenuation. In this study, the temporal dynamics of metazachlor and its transformation products metazachlor-oxalic acid (OA) and –sulphonic acid (ESA) were observed in an agricultural retention pond and hydrologic tracers helped to understand system-inherent processes. Pesticide measurements were carried out for 80 days after their application during transient flow conditions. During a short-term (3 days) experiment, the tracers bromide, uranine and sulphorhodamine B were used to determine hydraulic conditions, residence times and sorption potential. A long-term experiment with sodium naphthionate (2 months) and isotopes (12 months) provided information about inputs via interflow and surface-groundwater interactions. During transient conditions, high concentration pulses of up to 35 μg L−1 metazachlor, 14.7 μg L−1 OA and 22.5 μg L−1 ESA were quantified that enduringly raised solute concentrations in the pond. Mean residence time in the system accounted for approximately 4 h showing first tracer breakthrough after 5 min and last tracer concentrations 72 h after injection. While input via interflow was confirmed, no evidence for surface-groundwater interaction was found. Different tracers illustrated potentials for sorption and photolytic degradation inside the system. This study shows that high-resolution sampling is essential to obtain robust results about retention efficiency and that hydrological tracers may be used to determine the governing processes.
• Le Duy, N., Dung, N. V., Heidbüchel, I., Meyer, H., Weiler, M., Merz, B., Apel, H.
  Identification of groundwater mean transit times of precipitation and riverbank infiltration by two-component lumped parameter models
  2019 Hydrological Processes, volume: 33, issue: 24, pages: 3098 - 3118
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  Abstract

  Abstract Groundwater transit time is an essential hydrologic metric for groundwater resources management. However, especially in tropical environments, studies on the transit time distribution (TTD) of groundwater infiltration and its corresponding mean transit time (mTT) have been extremely limited due to data sparsity. In this study, we primarily use stable isotopes to examine the TTDs and their mTTs of both vertical and horizontal infiltration at a riverbank infiltration area in the Vietnamese Mekong Delta (VMD), representative of the tropical climate in Asian monsoon regions. Precipitation, river water, groundwater, and local ponding surface water were sampled for 3 to 9 years and analysed for stable isotopes (δ18O and δ2H), providing a unique data set of stable isotope records for a tropical region. We quantified the contribution that the two sources contributed to the local shallow groundwater by a novel concept of two-component lumped parameter models (LPMs) that are solved using δ18O records. The study illustrates that two-component LPMs, in conjunction with hydrological and isotopic measurements, are able to identify subsurface flow conditions and water mixing at riverbank infiltration systems. However, the predictive skill and the reliability of the models decrease for locations farther from the river, where recharge by precipitation dominates, and a low-permeable aquitard layer above the highly permeable aquifer is present. This specific setting impairs the identifiability of model parameters. For river infiltration, short mTTs (<40 weeks) were determined for sites closer to the river (<200 m), whereas for the precipitation infiltration, the mTTs were longer (>80 weeks) and independent of the distance to the river. The results not only enhance the understanding of the groundwater recharge dynamics in the VMD but also suggest that the highly complex mechanisms of surface–groundwater interaction can be conceptualized by exploiting two-component LPMs in general. The model concept could thus be a powerful tool for better understanding both the hydrological functioning of mixing processes and the movement of different water components in riverbank infiltration systems.
• Demand, D., Selker, J. S., Weiler, M.
  Influences of Macropores on Infiltration into Seasonally Frozen Soil
  2019 Vadose Zone Journal, volume: 18, issue: 1
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  Abstract

  Water frozen in soil can reduce the soil infiltrability, depending on the water content. We hypothesize that air-filled macropores control the infiltration of a seasonally frozen soil under high saturation degrees. Sprinkling experiments with different intensities on a seasonally frozen soil were conducted in two winters at high initial water contents. Brilliant Blue FCF (BB) was sprinkled on four plots equipped with soil moisture and temperature probes to mark flow paths. Frozen layer thickness was measured with infrared thermography of soil sections and overlaid with BB images. The frost depth of the experiments was 8 to 15 cm. Infiltration rates showed reduced infiltration compared with unfrozen conditions. By impeding refreezing of the infiltrating water with added NaCl, infiltration rates of 23 to 29 mm h-1 were measured. Without the addition of salt, the infiltration rates decreased to 5 to 10 mm h-1, attributed to pore blockage by refreezing water. Temperature measurements revealed that the frozen layer only thawed close to the soil surface during the experiments. Blue-stained areas indicated that water was channeled through the frozen layer into the unfrozen soil. In addition, the soil moisture probes below the frozen layer measured an increase in unfrozen water content, whereas total water content in the frozen layer was constant. These observations were explained by a connected air-filled porosity, such as biopores, which allowed water flow even under high initial water contents. These results illustrate the importance of macroporosity in relation to frost depth in controlling the infiltrability of seasonally frozen soils.
• Orlowski, N., Pratt, D. L., McDonnell, J. J.
  Intercomparison of soil pore water extraction methods for stable isotope analysis and interpretation of hillslope runoff sources
  2019 Hydrological Processes, volume: 33, issue: 22, pages: 2939 - 2954
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  Abstract

  Abstract Intercomparison of soil pore water extraction methods for stable isotope analysis has been a focus of recent studies in relation to plant source waters, which found a wide isotopic variance depending on the extraction method. Few studies have yet explored extraction effects for mobile pore waters that relate to hillslope runoff. This is because it is extremely difficult in natural systems to control the boundary conditions in order to assess and compare impacts of pore water extraction on resulting hillslope flow. With our new semicontrolled experiments on outdoor mini-hillslopes, we studied mixing and runoff processes by means of stable isotopes of water and quantified relations between pore water extraction methods. We tested the null hypothesis that nondestructive and destructive pore water sampling methods sample the same soil water pool. Three hillslopes were mounted on load cells, filled with loamy sand textured soils from the Landscape Evolution Observatoryat Biosphere 2, equipped with soil moisture and temperature sensors, a bottom outflow, and a surface runoff gauge for isotope sampling. We followed the precipitation isotopic composition over and through the soil profile. One hillslope was instrumented with suction cups, on the second we installed sampling ports for in-situ soil water vapour measurements, and the third hillslope was sampled destructively for applying the centrifugation and vapour equilibrium methods. All hillslopes were sampled at four depths (0–10, 10–20, 20–30, and 30–40 cm) at three different downslope positions. 2H and 18O analyses were performed via laser spectroscopy. We found no isotopic differences between rainfall, surface runoff, and bottom outflow. The in situ vapour ports' soil isotope data showed the widest spread over all hillslope positions and depths. Centrifugation's and suction cups' isotope results plotted closest to the local meteoric water line and within the range of hillslope runoff and bottom outflow data. Hillslope position did not influence the soil isotope results. These results suggest caution be used in the field when selecting an extraction technique for matching soil waters to runoff waters. Soil suction lysimeters and centrifugation appeared to be the most appropriate tools in this regard.
• Fernández-Pascual, E., Zaman, S., Bork, M., Lang, F., Lange, J.
  Long-term mesocosm experiments to investigate degradation of fluorescent tracers
  2019 Journal of Hydrology X, volume: 2, page: 100014
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  Abstract

  The choice of uranine (UR) and sulforhodamine B (SRB) as hydrological tracers has recently been questioned since they might interact with the soil or become degraded. In this context, microbiological degradation of UR and SRB and the factors influencing it remain poorly studied. Here, we conducted a long-term mesocosm experiment where the effects of plants and hydrologic conditions on the dissipation and degradation of UR and SRB was separately investigated. Mass balances were combined with excitation emission matrix (EEM) fluorescence spectroscopy to characterize microbially-derived organic matter. Results revealed that most of SRB accumulated in the sand while UR was mainly found in the pore water. The estimated degradation of UR and SRB was greater in the treatments with plants and under unsaturated conditions. Overall, UR exhibited higher presumable degradation than SRB. Two components were identified by parallel factor analysis of the EEMs in addition to the UR-related component (U), one humic-like of high molecular weight primarily derived from terrestrial or soil organic matter sources (A + C) and a second humic-like of lower molecular weight related to recent microbial activity (M). A high positive correlation (Spearman’s rho = 0.74, p < 0.001) between M and U suggested a possible link, in which the presence of UR fostered microbial processes, thus supporting the hypothesis of biodegradation of UR, which seemed independent of the presence of plants, whereas it was not possible to point out such a correlation for SRB. These results show for the first time that plants and the alternation of oxic and anoxic conditions are favourable to increase degradation of UR and SRB and that microbiological degradation can be involved and dominant in UR dissipation.
• Kaplan, N. H., Sohrt, E., Blume, T., Weiler, M.
  Monitoring ephemeral, intermittent and perennial streamflow: a dataset from 182 sites in the Attert catchment, Luxembourg
  2019 Earth Syst. Sci. Data, Copernicus Publications, volume: 11, issue: 3, pages: 1363 - 1374
• Weiler, M., Hänsler, A., Zimmer, J., Moser, M.
  Nutzung von Radardaten im Starkregenrisikomanagement in Baden-Württemberg
  2019 WasserWirtschaft, volume: 12-2019, pages: 63 - 67
• Sohrt, J., Uhlig, D., Kaiser, K., von Blanckenburg, F., Siemens, J., Seeger, S., Frick, D. A., Krüger, J., Lang, F., Weiler, M.
  Phosphorus Fluxes in a Temperate Forested Watershed: Canopy Leaching, Runoff Sources, and In-Stream Transformation
  2019 Frontiers in Forests and Global Change, volume: 2, issue: 85
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  Abstract

  Declining foliar phosphorus (P) levels call increasing attention to the cycling of this element in temperate forests. We explored the fluxes of P in a temperate mixed deciduous forest ecosystem in six distinct hydrological compartments: Bulk precipitation and throughfall, soil water draining laterally from three different soil depths (0–15, 15–150, 150–320 cm below soil surface), groundwater, creek and spring discharge, which were sampled at daily to bi-weekly resolution from March 2015 to February 2016. Atmospheric P fluxes into the ecosystem were equally partitioned between wet and dry deposition. Approximately 10% of the foliar P stock was lost annually by foliar leaching during late summer. The concentrations of dissolved P in soil water from the forest floor and upper mineral topsoil followed a pronounced seasonal cycle with higher concentrations during the vegetation period. The concentrations of P dissolved in soil water decreased with increasing soil depth. Using an end member mixing analysis (EMMA) we found that P sources feeding the spring water were both soil water from greater depths or groundwater with season specific contributions. Atmospheric P fluxes into the ecosystem determined in this study and P-release from weathering reported for the research site were large enough to compensate P losses with runoff. This suggests that declining foliar P levels of forests are unlikely the result of a dwindling total P supply, but rather caused by tree nutrition imbalances or alternative stressors.
• Zuecco, G., Rinderer, M., Penna, D., Borga, M., van Meerveld, H. J.
  Quantification of subsurface hydrologic connectivity in four headwater catchments using graph theory
  2019 Science of the Total Environment, volume: 646, pages: 1265 - 1280
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  Abstract

  Hillslope-stream connectivity significantly affects streamflow and water quality responses during rainfall and snowmelt events, but is difficult to quantify. One approach to quantify subsurface hillslope-stream connectivity is graph theory, which considers linear connections between groundwater measurement sites. We quantified subsurface connectivity based on surface topography and shallow groundwater data from four small (<14 ha) headwater catchments in the Italian Dolomites and the Swiss pre-Alps, determined the relation between rainfall, antecedent wetness conditions and subsurface connectivity and assessed the sensitivity of the results to changes in the measurement network. Event total stormflow was correlated to maximum subsurface connectivity. Subsurface connectivity increased during rainfall events but maximum connectivity occurred later than peak streamflow, resulting in anti-clockwise hysteretic relations between the two. Subsurface connectivity was positively correlated to rainfall amount. Maximum subsurface connectivity was related to the sum of total rainfall plus antecedent rainfall for the Dolomitic catchments, but these relations were less clear for the pre-alpine catchments. For the pre-alpine catchments, the fractions of time that the groundwater monitoring sites were connected to the stream were significantly correlated to the upslope site characteristics, such as the Topographic Wetness Index. For the Dolomitic catchments, the fractions of time that the monitoring sites were connected to the stream were correlated to the topographic characteristics of the upslope contributing area for the catchment with the small riparian zone, and with the distance to the nearest stream for the catchment with the large riparian zone. The leave-one-out sensitivity analysis showed that small changes in the structure of the groundwater monitoring networks had a limited influence on the results, suggesting that graph-theory approaches can be used to describe subsurface hydrologic connectivity. However, the proposed graph-theory approach should be verified in other catchments with different groundwater monitoring networks.
• Demand, D., Blume, T., Weiler, M.
  Spatio-temporal relevance and controls of preferential flow at the landscape scale
  2019 Hydrol. Earth Syst. Sci., volume: 23, issue: 11, pages: 4869 - 4889
• Sprenger, M., Stumpp, C., Weiler, M., Aeschbach, W., Allen, S. T., Benettin, P., Dubbert, M., Hartmann, A., Hrachowitz, M., Kirchner, J. W., McDonnell, J. J., Orlowski, N., Penna, D., Pfahl, S., Rinderer, M., Rodriguez, N., Schmidt, M., Werner, C.
  The Demographics of Water: A Review of Water Ages in the Critical Zone
  2019 Reviews of Geophysics, volume: 57, issue: 3, pages: 800 - 834
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  Abstract

  Abstract The time that water takes to travel through the terrestrial hydrological cycle and the critical zone is of great interest in Earth system sciences with broad implications for water quality and quantity. Most water age studies to date have focused on individual compartments (or subdisciplines) of the hydrological cycle such as the unsaturated or saturated zone, vegetation, atmosphere, or rivers. However, recent studies have shown that processes at the interfaces between the hydrological compartments (e.g., soil-atmosphere or soil-groundwater) govern the age distribution of the water fluxes between these compartments and thus can greatly affect water travel times. The broad variation from complete to nearly absent mixing of water at these interfaces affects the water ages in the compartments. This is especially the case for the highly heterogeneous critical zone between the top of the vegetation and the bottom of the groundwater storage. Here, we review a wide variety of studies about water ages in the critical zone and provide (1) an overview of new prospects and challenges in the use of hydrological tracers to study water ages, (2) a discussion of the limiting assumptions linked to our lack of process understanding and methodological transfer of water age estimations to individual disciplines or compartments, and (3) a vision for how to improve future interdisciplinary efforts to better understand the feedbacks between the atmosphere, vegetation, soil, groundwater, and surface water that control water ages in the critical zone.
• Allen, S. T., von Freyberg, J., Weiler, M., Goldsmith, G. R., Kirchner, J. W.
  The Seasonal Origins of Streamwater in Switzerland
  2019 Geophysical Research Letters, volume: 46, issue: 17-18, pages: 10425 - 10434
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  Abstract

  Abstract Quantifying the relative contributions of winter versus summer precipitation to streamflow may be important for understanding water-resource sensitivity to precipitation variability. Here we compare volume-weighted mean δ18O values in precipitation and streamflow for 12 catchments in Switzerland, to determine whether summer or winter precipitation is overrepresented in streamflow, relative to its proportion of total precipitation. Similarities between precipitation and streamflow weighted-mean δ18O values indicate that roughly equal fractions of summer and winter precipitation supply streams in Switzerland. These results, together with mass conservation, suggest that similar fractions of summer and winter precipitation supply evapotranspiration. These findings contrast with the assumption that because summer precipitation falls when transpiration rates and evaporative demand are high, it should be underrepresented in streamflow and overrepresented in evapotranspiration. This contrast between seasonal water-balance variations and the partitioning of seasonal precipitation into runoff and evapotranspiration demonstrates substantial interseasonal carryover of precipitation in storages that supply evapotranspiration.
• Staudinger, M., Stoelzle, M., Cochand, F., Seibert, J., Weiler, M., Hunkeler, D.
  Your work is my boundary condition!: Challenges and approaches for a closer collaboration between hydrologists and hydrogeologists
  2019 Journal of Hydrology, volume: 571, pages: 235 - 243
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  Abstract

  Hydrologists and hydrogeologists both study the flux and storage of water with the numerous interactions and feedback mechanisms of surface water and groundwater. Traditionally however, focus, models and scales of the studies differ. In this commentary, situations are illustrated where boundary conditions that each discipline assumes, preserves and actively uses, can and have to be overcome. These situations occur when the domain of one discipline cannot be separated from the other one because of existing interaction and feedback mechanisms at the boundaries. Highlighted are especially these boundary conditions, where closer collaboration between catchment hydrologists and hydrogeologists would be most useful. Often such collaborations would be relatively straight-forward and rather requiring an increased awareness than novel methods.
• Schmieder, J., Seeger, S., Weiler, M., Strasser, U.
  ‘Teflon Basin’ or Not? A High-Elevation Catchment Transit Time Modeling Approach
  2019 Hydrology, volume: 6, issue: 4, page: 92

2018

• Orlowski, N., Winkler, A., McDonnell, J.J., Breuer, L.
  A simple greenhouse experiment to explore the effect of cryogenic water extraction for tracing plant source water
  2018 Ecohydrology, volume: 11, issue: 5
• Paparrizos, S., Maris, F., Weiler, M., Matzarakis, A.
  Analysis and mapping of present and future drought conditions over Greek areas with different climate conditions
  2018 Theoretical and Applied Climatology, volume: 131, issue: 1, pages: 259 - 270
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  Abstract

  Estimation of drought in a certain temporal and spatial scale is crucial in climate change studies. The current study targets on three agricultural areas widespread in Greece, Ardas River Basin in Northeastern Greece, Sperchios River Basin in Central Greece, and Geropotamos River Basin in Crete Island in South Greece that are characterized by diverse climates as they are located in various regions. The objective is to assess the spatiotemporal variation of drought conditions prevailing in these areas. The Standardized Precipitation Index (SPI) was used to identify and assess the present and future drought conditions. Future simulated data were derived from a number of Regional Climatic Models (RCMs) from the ENSEMBLES European Project. The analysis was performed for the future periods of 2021–2050 and 2071–2100, implementing A1B and B1 scenarios. The spatial analysis of the drought conditions was performed using a combined downscaling technique and the Ordinary Kriging. The Mann-Kendall test was implemented for trend investigation. During both periods and scenarios, drought conditions will tend to be more severe in the upcoming years. The decrease of the SPI values in the Sperchios River Basin is expected to be the strongest, as it is the only study area that will show a negative balance (in SPI values), regarding the drought conditions. For the Ardas and the Geropotamos River Basins, a great increase of the drought conditions will occur during the 2021–2050 period, while for 2071–2100 period, the decrease will continue but it will be tempered. Nevertheless, the situation in all study areas according to the SPI classification is characterized as “Near-normal”, in terms of drought conditions.
• Rinderer, M., Ali, G., Larsen, L. G.
  Assessing structural, functional and effective hydrologic connectivity with brain neuroscience methods: State-of-the-art and research directions
  2018 Earth-Science Reviews, volume: 178, pages: 29 - 47
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  Abstract

  While the concept of connectivity has gained popularity in fields like hydrology and ecology, little agreement exists on its definition, which hinders its use in both scientific and legal contexts. In contrast, neuroscientists have developed not only strong conceptualizations of connectivity but also tools to quantify it: a clear distinction is made between structural connectivity, which is determined from brain anatomy; functional connectivity, which is estimated based on statistical dependencies between neuronal electric timeseries; and effective connectivity, which infers causal relations from the same timeseries based on the assumption that “true” interactions occur with a certain time delay. The motivation of this review arose from the hypothesis that connectivity-related statistical techniques, which are applied to timeseries of electrical currents measured by placing electrodes on the scalp of the human brain, could also apply to high-frequency hydrological timeseries acquired to characterize catchment response to precipitation. Here we bring together existing conceptualizations of structural, functional and effective connectivity in hydrology and ecology and compare them with those used in brain neuroscience. We then summarize the most important brain connectivity measures and their associated mathematical frameworks before evaluating the potential of those measures to help advance our understanding of hydrologic connectivity properties – in terms of the frequency, magnitude, timing, duration and rate of water movement linking two disparate locations. Lastly, we present a short case study where a selection of brain connectivity measures is applied to 35 groundwater and streamflow timeseries from a Swiss catchment to infer subsurface flow-driven hydrologic connectivity. Our literature review combined with our short case study suggest that an ensemble of functional and effective connectivity measures should be used and constrained not only by structural connectivity measures but also by interpretation thresholds in order to make results parsimonious. We highlight challenges associated with transferring brain connectivity measures to hydrology, especially those related to choosing the appropriate length and sampling frequency of input timeseries when assessing perennial versus ephemeral connectivity, appropriately detecting and differentiating noisy from indirect connections, and interpreting unbounded connectivity measures. We then offer recommendations for future research and propose that hydrologists use a common classification system encompassing all potential connectivity assessment approaches and measures in order to facilitate scientific communication.
• Messerschmid, C., Lange, J., Sauter, M.
  Assessment of transmission loss in a Mediterranean karstic watershed (Wadi Natuf, West Bank)
  2018 Hydrological Processes, volume: 32, issue: 10, pages: 1375 - 1390
• Gralher, B., Herbstritt, B., Weiler, M., Wassenaar, L. I., Stumpp, C.
  Correcting for Biogenic Gas Matrix Effects on Laser-Based Pore Water-Vapor Stable Isotope Measurements
  2018 Vadose Zone Journal, volume: 17, issue: 1
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  Abstract

  The isotopic composition (δ2H, δ18O) of pore water is an invaluable tracer for the minimally invasive study of subsurface water flow and transport processes. Here, we evaluated a method for pore water isotope analysis that combines laser-based isotope analyzers and water-vapor isotope equilibration using evaporation-proof metalized sample bags. We tested inflation atmospheres (dry air vs. pure N2) and the impact of biogenic gas (CO2, CH4) accumulation for storage times of up to 4 wk. Samples were analyzed with a water isotope analyzer (Picarro L2120-i) and a gas chromatograph. Air-inflated water vapor samples showed a greater range of gas matrix effects (δ18O: 9.63‰; δ2H: 21.7‰) than N2–inflated samples (δ18O: 7.49‰; δ2H: 10.6‰) induced by nonuniform buildup of biogenic CO2, starting immediately after sample preparation. However, only air-inflated samples could be reliably corrected using instrument-specific sensitivity factors that were empirically determined by interpretation of periodically repeated isotope measurements. Corrected water isotope data were confirmed by similarity with local precipitation and suction cup isotope data. Residual uncertainties were well below the natural variations of soil water isotope values and independent of storage time, thus allowing for consistently reliable interpretations of soil water isotope profiles. We conclude that, especially for pore water sampling that requires small sample volumes and/or long storage times, metalized sample bags should be used to prevent evaporation notwithstanding the enhanced buildup of biogenic gases. Further, if gas matrix effects cannot be excluded, air inflation is preferred over pure N2, as only in that case can reliable postcorrections be performed by using internal data only.
• Schwab, M. P., Klaus, J., Pfister, L., Weiler, M.
  Diel fluctuations of viscosity-driven riparian inflow affect streamflow DOC concentration
  2018 Biogeosciences, Copernicus Publications, volume: 15, issue: 7, pages: 2177 - 2188
• Brinkmann, N., Seeger, S., Weiler, M., Buchmann, N., Eugster, W., Kahmen, A.
  Employing stable isotopes to determine the residence times of soil water and the temporal origin of water taken up by Fagus sylvatica and Picea abies in a temperate forest
  2018 New Phytologist, volume: 219, issue: 4, pages: 1300 - 1313
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  Abstract

  Summary We assessed how the seasonal variability of precipitation δ2H and δ18O is propagated into soil and xylem waters of temperate trees, applied a hydrological model to estimate the residence time distribution of precipitation in the soil, and identified the temporal origin of water taken up by Picea abies and Fagus sylvatica over 4 yr. Residence times of precipitation in the soil varied between a few days and several months and increased with soil depth. On average, 50% of water consumed by trees throughout a year had precipitated during the growing season, while 40% had precipitated in the preceding winter or even earlier. Importantly, we detected subtle differences with respect to the temporal origin of water used by the two species. We conclude that both current precipitation and winter precipitation are important for the water supply of temperate trees and that winter precipitation could buffer negative impacts of spring or summer droughts. Our study additionally provides the means to obtain realistic estimates of source water δ2H and δ18O values for trees from precipitation isotope data, which is essential for improving model-based interpretations of δ18O and δ2H values in plants.
• Hensen, B., Lange, J., Jackisch, N., Zieger, F., Olsson, O., Kümmerer, K.
  Entry of biocides and their transformation products into groundwater via urban stormwater infiltration systems
  2018 Water Research, volume: 144, pages: 413 - 423
• Steinbrich, A., Henrichs, M., Leistert, H., Scherer, I., Schütz, T., Uhl, M., Weiler, M.
  Ermittlung eines naturnahen Wasserhaushalts als Planungsziel für Siedlungen
  2018 Hydrologie und Wasserbewirtschaftung, volume: 62. Jahrgang, issue: Heft 6, pages: 400 - 409
• Lange, J., Olsson, O., Sweeney, B., Herbstritt, B., Reich, M., Alvarez-Zaldivar, P., Payraudeau, S., Imfeld, G.
  Fluorescent tracers to evaluate pesticide dissipation and transformation in agricultural soils
  2018 Science of the Total Environment, volume: 619-620, pages: 1682 - 1689
• Sohrt, J., Herschbach, C., Weiler, M.
  Foliar P- but not N resorption efficiency depends on the P-concentration and the N:P ratio in trees of temperate forests
  2018 Trees, volume: 32, issue: 5, pages: 1443 - 1455
  » show abstract« hide abstract
  Abstract

  While there is evidence that foliar P concentration controls foliar P resorption efficiency, this is not found for N. Likewise, the foliar N:P ratio affects P, but not N resorption.
• Freudiger, D., Mennekes, D., Seibert, J., Weiler, M.
  Historical glacier outlines from digitized topographic maps of the Swiss Alps
  2018 Earth Syst. Sci. Data, volume: 10, pages: 805 - 814
• Blume, T., van Meerveld, I., Weiler, M.
  Incentives for field hydrology and data sharing: collaboration and compensation: reply to “A need for incentivizing field hydrology, especially in an era of open data”*
  2018 Hydrological Sciences Journal, volume: 63, issue: 8, pages: 1266 - 1268
• Orlowski, N., Breuer, L., Angeli, N., Boeckx, P., Brumbt, C., Cook, C. S., Dubbert, M., Dyckmans, J., Gallagher, B., Gralher, B., Herbstritt, B., Hervé-Fernández, P., Hissler, C., Koeniger, P., Legout, A., Macdonald, C. J., Oyarzún, C., Redelstein, R., Seidler, C., Siegwolf, R., Stumpp, C., Thomsen, S., Weiler, M., Werner, C., McDonnell, J. J.
  Inter-laboratory comparison of cryogenic water extraction systems for stable isotope analysis of soil water
  2018 Hydrology and Earth System Sciences, Copernicus Publications, volume: 22, issue: 7, pages: 3619 - 3637
• Weiler, M., Seibert, J., Stahl, K.
  Magic components—why quantifying rain, snowmelt, and icemelt in river discharge is not easy
  2018 Hydrological Processes, volume: 32, issue: 1, pages: 160 - 166
• Sprenger, S., Tetzlaff, D. , Buttle, J., Laudon, H., Leistert, H., Mitchell, C. P. J., Snelgrove, J., Weiler, M., Soulsby, C.
  Measuring and Modeling Stable Isotopes of Mobile and Bulk Soil Water
  2018 Vadose Zone Journal, volume: 17, issue: 1
• Brenner, S., Coxon, G., Howden, N. J. K., Freer, J., Hartmann, A.
  Process-based modelling to evaluate simulated groundwater levels and frequencies in a Chalk catchment in south-western England
  2018 Nat. Hazards Earth Syst. Sci., volume: 18, pages: 445 - 461
  
   
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• Mahindawansha, A., Orlowski, N., Kraft, P., Rothfuss, Y., Racela, H., Breuer, L.
  Quantification of plant water uptake by water stable isotopes in rice paddy systems
  2018 Plant and Soil, volume: 429, issue: 1-2, pages: 281 - 302
• van Meerveld, H.J.I. , Fischer, B.M.C., Rinderer, M., Stähli, M., Seibert, J.
  Runoff generation in a pre-alpine catchment: A discussion between a tracer and a shallow groundwater hydrologist
  2018 Cuadernos de Investigación Geográfica (CIG), volume: 44
• von Freyberg, J., Allen, S. T., Seeger, S., Weiler, M., Kirchner, J. W.
  Sensitivity of young water fractions to hydro-climatic forcing and landscape properties across 22 Swiss catchments
  2018 Hydrology and Earth System Sciences, volume: 22, pages: 3841 - 3861
• von Freyberg, J., Studer, B., Rinderer, M., Kirchner, J. W.
  Studying catchment storm response using event- and pre-event-water volumes as fractions of precipitation rather than discharge
  2018 Hydrology and Earth System Sciences, Copernicus Publications, volume: 22, issue: 11, pages: 5847 - 5865
• Seibert, J., Vis, M. J. P., Kohn, I., Weiler, M., Stahl, K.
  Technical note: Representing glacier geometry changes in a semi-distributed hydrological model
  2018 Hydrology and Earth System Sciences, volume: 22, pages: 2211 - 2224
• Hassler, S. K., Weiler, M., Blume, T.
  Tree-, stand- and site-specific controls on landscape-scale patterns of transpiration
  2018 Hydrol. Earth Syst. Sci., volume: 22, pages: 13 - 30

2017

• Chen, Z., Hartmann, A., Goldscheider, N.
  A new approach to evaluate spatiotemporal dynamics of controlling parameters in distributed environmental models
  2017 Environmental Modelling & Software, volume: 87, issue: 1-16
• van Verseveld, W. J., Barnard, H. R., Graham, C. B., McDonnell, J. J., Brooks, J. R., Weiler, M.
  A sprinkling experiment to quantify celerity–velocity differences at the hillslope scale
  2017 Hydrology and Earth System Sciences, volume: 21, pages: 5891 - 5910
• Demand, D., Schack-Kirchner, H., Lang, F.
  Assessment of diffusive phosphate supply in soils by microdialysis
  2017 J. Plant Nutr. Soil Sci., volume: 180, pages: 220 - 230
• Staudinger, M., Stoelzle, M., Seeger, S., Seibert, J., Weiler, M., Stahl, K.
  Catchment water storage variation with elevation
  2017 Hydrological Processes, volume: 31, issue: 11, pages: 2000 - 2015
• Ries, F., Schmidt, S., Sauter, M., Lange, J.
  Controls on runoff generation along a steep climatic gradient in the Eastern Mediterranean
  2017 Journal of Hydrology: Regional Studies, volume: 9, pages: 18 - 33
• Angermann, L., Jackisch, C., Allroggen, N., Sprenger, M., Zehe, E., Tronicke, J., Weiler, M., Blume, T.
  Form and function in hillslope hydrology: characterization of subsurface flow based on response observations
  2017 Hydrology and Earth System Sciences, volume: 21, pages: 3727 - 3748
• Jackisch, C., Angermann, L., Allroggen, N., Sprenger, M., Blume, T., Weiler, M., Tronicke, J., Zehe, E.
  Form and function in hillslope hydrology: in situ imaging and characterization of flow-relevant structures
  2017 Hydrology and Earth System Sciences Discussion, volume: 21, pages: 3749 - 3775
  
   
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• Rinderer, M., McGlynn, B.L., van Meerveld, H.J.
  Groundwater similarity across a watershed derived from time-warped and flow-corrected time series
  2017 Water Resources Research, volume: 53, issue: 5, pages: 3921 - 3940
• Schwab, M. P., Klaus, J., Pfister, L., Weiler, M.
  How runoff components affect the export of DOC and nitrate: a long-term and high-frequency analysis
  2017 Hydrol. Earth Syst. Sci. Discuss., Copernicus Publications, volume: 2017, pages: 1 - 21
• Soulsby, C., Braun, H., Sprenger, M., Weiler, M., Tetzlaff, D.
  Influence of forest and shrub canopies on precipitation partitioning and isotopic signatures
  2017 Hydrological Processes, volume: 21, issue: 24, pages: 4282 - 4296
• Weiler, M.
  Macropores and preferential flow - a love-hate relationship
  2017 Hydrological Processes, volume: 31, issue: 1, pages: 15 - 19
• Gaj, M., Kaufhold, S., Koeniger, P., Beyer, M. , Weiler, M., Himmelsbach, T.
  Mineral mediated isotope fractionation of soil water
  2017 Rapid Communications in Mass Spectrometry, volume: 31, issue: 3, page: 269–280
• Scherer, I., Henrichs, M., Uhl, M., Schütz, T., Weiler, M., Hackenbroch, K., König, F., Freytag, T.
  Planungsinstrumente und Bewirtschaftungskonzepte für den Wasserhaushalt in Siedlungen
  2017 Korrespondenz Wasserwirtschaft, volume: 10, issue: 4, pages: 221 - 228
• Sohrt, J., Lang, F., Weiler, M.
  Quantifying components of the phosphorus cycle in temperate forests
  2017 WIREs Water, volume: 4, issue: 6, pages: 1 - 36
• Freudiger, D., Kohn, I., Seibert, J., Stahl, K., Weiler, M.
  Snow redistribution for the hydrological modeling of alpine catchments
  2017 WIREs Water, volume: 4, issue: 5, pages: 1 - 16
• Laaha, G., Gauster, T., Tallaksen, L.M., Vidal, J.-P., Stahl, K., Prudhomme, C., Heudorfer, B., Vlnas, R., Ionita, M., Van Lanen, H.A.J., Adler, M.-J., Caillouet, L., Delus, C., Fendekova, M., Gailliez, S., Hannaford, J., Kingston, D., Van Loon, A.F., Mediero, L., Osuch, M., Romanowicz, R., Sauquet, E., Stagge, J.H., Wong, W.K.
  The European 2015 drought from a hydrological perspective
  2017 Hydrol. Earth Syst. Sci., volume: 21, pages: 3001 - 3024
  
   
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• Jackisch, N., Weiler, M
  The hydrologic outcome of a Low Impact Development (LID) site including superposition with streamflow peaks
  2017 Urban Water Journal, volume: 14, issue: 2, pages: 143 - 159
• Blume, T., van Meerveld, I., Weiler, M.
  The role of experimental work in hydrological sciences – insights from a community survey
  2017 Hydrological Sciences Journal, volume: 62, issue: 3, pages: 334 - 337
• Stahl, K., Weiler, M., Freudiger, D., Kohn, I., Seibert, J., Vis,M., Gerlinger,K., Böhm, M.
  The snow and glacier melt components of the streamflow of the River Rhine and its tributaries considering the influence of climate change. Final report to the International Commission for the Hydrology of the Rhine basin (CHR). English version, March 2017.
  2017
• Lange, J., Olsson, O., Jackisch, N., Weber, T., Hensen, B., Zieger, F., Schütz, T., Kümmerer, K.
  Urbane Regenwasserversickerung als Eintragspfad für biozide Wirkstoffe in das Grundwasser?
  2017 Korrespondenz Wasserwirtschaft, volume: 4, pages: 198 - 202
• Karthe, D., Chifflard, P., Cyffka, B., Menzel, L., Nacken, H., Raeder, U., Sommerhäuser, M., Weiler, M.
  Water research in Germany: from the reconstruction of the Roman Rhine to a risk assessment for aquatic neophytes
  2017 Environmental Earth Sciences, volume: 76:549, pages: 1 - 16
• Gunkel, A., Lange, J.
  Water scarcity, data scarcity and the Budyko curve—An application in the Lower Jordan River Basin
  2017 Journal of Hydrology: Regional Studies, volume: 12, pages: 136 - 149

2016

• Volkmann, T.H.M., Kühnhammer, K., Herbstritt, B., Gessler, A., Weiler, M.
  A method for in situ monitoring of the isotope composition of tree xylem water using laser spectroscopy
  2016 Plant, Cell & Environment, volume: 39, issue: 9, page: 2055–2063
• Bachmair, S., Svensson, C. , Hannaford, J., Barker, L. J., Stahl, K.
  A quantitative analysis to objectively appraise drought indicators and model drought impacts
  2016 Hydrology and Earth System Sciences, volume: 20, pages: 2589 - 2609
• Schwerdtfeger, J., Hartmann, A., Weiler, M.
  A tracer-based simulation approach to quantify seasonal dynamics of surface-groundwater interactions in the Pantanal wetland
  2016 Hydrological Processes, volume: 30, issue: 15, page: 2590–2602
• Stahl, K., Weiler, M., Freudiger, D., Kohn, I., Seibert, J., Vis,M., Gerlinger,K., Böhm, M.
  Abflussanteile aus Schnee- und Gletscherschmelze im Rhein und seinen Zuflüssen vor dem Hintergrund des Klimawandels. Abschlussbericht an die Internationale Kommission für die Hydrologie des Rheingebietes (KHR). Überarbeitete Endfassung Dezember 2016.
  2016
• Stahl, K., Weiler, M., Kohn, I., Freudiger, D., Seibert, J., Vis, M., Gerlinger, K., Böhm, M.
  Abfussanteile aus Schnee- und Gletscherschmelze im Rhein und seinen Zufüssen vor dem Hintergrund des Klimawandels - Synthesebericht
  2016
• Paparrizos, S., Maris, F., Weiler, M., Matzarakis, A.
  Analysis and mapping of present and future drought conditions over Greek areas with different climate conditions
  2016 Theoretical and Applied Climatology, pages: 1 - 12
• Heudorfer, B., Stahl, K.
  Comparison of different threshold level methods for drought propagation analysis in Germany
  2016 Hydrology Research, volume: 48, issue: 6
• Tijdeman, E., Bachmair, S., Stahl, K.
  Controls on hydrologic drought duration in near-natural streamflow in Europe and the USA
  2016 Hydrology and Earth System Sciences Discussion, volume: 20, pages: 4043 - 4059
  
   
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• Tijdeman, E., Bachmair, S., Stahl, K.
  Controls on hydrologic drought duration in near-natural streamflow in Europe and the USA
  2016 Hydrology and Earth System Sciences, volume: 20, pages: 4043 - 4059
• Gralher, B., Herbstritt, B., Weiler, M., Wassenaar, L.I., Stumpp, C.
  Correcting laser-based water stable isotope readings biased by carrier gas changes
  2016 Environmental Science & Technology, volume: 50, issue: 13, pages: 7074 - 7081
• Freudiger, D., Frielingsdorf, B., Stahl, K., Steinbrich, A., Weiler, M., Griessinger, N. , Seibert, J.
  Das Potential meteorologischer Rasterdatensätze für die Modellierung der Schneedecke alpiner Einzugsgebiete
  2016 Hydrologie & Wasserbewirtschaftung, volume: 60, issue: 6, pages: 353 - 367
• Schwab, M., Klaus, J., Pfister, L., Weiler, M.
  Diel discharge cycles explained through viscosity fluctuations in riparian inflow
  2016 Water Resources Research, volume: 52, issue: 11, pages: 8744 - 8755
• Elodie Maillard, Jens Lange, Steffi Schreiber, Jeanne Dollinger, Barbara Herbstritt, Maurice Millet, Gwenaël Imfeld
  Dissipation of hydrological tracers and the herbicide S-metolachlor in batch and continuous-flow wetlands
  2016 Chemosphere, volume: 144, pages: 2489 - 2496
• Bol, R., Julich, D., Brödlin, D., Siemens, J., Kaiser, K., Dippold, M.A., Spielvogel, S., Zilla, T., Mewes, D., von Blanckenburg, F., Puhlmann, H., Holzmann, S., Weiler, M., Amelung, W., Lang, F., Kuzyakov, Y., Feger, K.-H., Gottselig, N., Klumpp, E., Missong, A., Winkelmann, C., Uhlig, D., Sohrt, J., von Wilpert, K., Wu, B., Hagedorn, F.
  Dissolved and colloidal phosphorus fluxes in forest ecosystems - an almost blind spot in ecosystem research
  2016 Plant Nutr. Soil Sci., volume: 179, page: 425–438
• Lange, J., Materne, T., Grüner, J.
  Do low-cost ceramic water filters improve water security in rural South Africa?
  2016 Drinking Water Engineering and Science, volume: 9, pages: 47 - 55
• Renner, M., Hassler, S. K., Blume, T., Weiler, M., Hildebrandt, A., Guderle, M., Schymanski, S. J., Kleidon, A.
  Dominant controls of transpiration along a hillslope transect inferred from ecohydrological measurements and thermodynamic limits
  2016 Hydrology and Earth System Sciences, volume: 20, pages: 2063 - 2083
• Van Loon, A. F., Stahl, K., Di Baldassarre, G., Clark, J., Rangecroft, S., Wanders, N., Gleeson, T., Van Dijk, A. I. J. M., Tallaksen, L. M., Hannaford, J., Uijlenhoet, R., Teuling, A. J., Hannah, D. M., Sheffield, J., Svoboda, M., Verbeiren, B., Wagener, T., Van Lanen, H. A. J
  Drought in a human-modified world: reframing drought definitions, understanding, and analysis approaches
  2016 Hydrology and Earth System Sciences, volume: 20, pages: 3631 - 3650
• Van Loon, A. F., Gleeson, T., Clark, J., Van Dijk, A. I. J. M., Stahl, K., Hannaford, J., Di Baldassarre, G., Teuling, A. J., Tallaksen, L. M., Uijlenhoet, M, Hannah, D. M., Sheffield, J., Svoboda, M., Verbeiren, M., Wagener, T., Rangecroft, S., Wanders, N., Van Lanen, H. A. J.
  Drought in the Anthropocene
  2016 Nature Geoscience, volume: 9, issue: 89–9
• Bachmair, S., Stahl, K., Collins, K., Hannaford, J., Acreman, M., Svoboda, M., Knutson, C., Smith, K., Wall, N., Fuchs, B., Crossman, N., Overton, I.
  Drought indicators revisited: the need for a wider consideration of environment and society
  2016 WIREs: Water
• Beckers, J. V. L., Weerts, A. H., Tijdeman, E., Welles, E.
  ENSO-conditioned weather resampling method for seasonal ensemble streamflow prediction
  2016 Hydrology and Earth System Sciences, volume: 20, pages: 3277 - 3287
• Kopp, B.J., Lange, J., Menzel, L.
  Effects of wildfire on runoff generating processes in northern Mongolia
  2016 Regional Environmental Change, pages: 1 - 13
• Blauhut, V., Stahl, K., Stagge, J. H., Tallaksen, L. M., De Stefano, L., Vogt, J
  Estimating drought risk across Europe from reported drought impacts, drought indices, and vulnerability factors
  2016 Hydrology and Earth System Sciences, volume: 20, pages: 2779 - 2800
• Steinbrich, A., Stölzle, M., Weiler, M.
  Generierung von konsistenten Grundlagendaten zur Berechnung von Starkregenereignissen für eine Starkregengefahrenkartierung in BW
  2016 , volume: IHF-Bericht No 152
• Volkmann, T.H.M., Haberer, K., Gessler, A., Weiler, M.
  High-resolution isotope measurements resolve rapid ecohydrological dynamics at the soil-plant interface
  2016 New Phytologist, volume: 210, issue: 3, pages: 839 - 849
• Sprenger, M., Erhardt, M., Riedel, M., Weiler, M.
  Historical tracking of nitrate in contrasting vineyards using water isotopes and nitrate depth profiles
  2016 Agriculture Ecosystems & Environment, volume: 222, page: 185–192
• Van Lanen, H. A. J., Laaha, G., Kingston, D. G., Gauster, T., Ionita, M., Vidal, J.-P., Vlnas, R., Tallaksen, L. M., Stahl, K., Hannaford, J., Delus, C., Fendekova, M., Mediero, L., Prudhomme, C., Rets, E., Romanowicz, R. J., Gailliez, S., Wong, W. K., Adler, M.-J., Blauhut, V., Caillouet, L., Chelcea, S., Frolova, N., Gudmundsson, L., Hanel, M., Haslinger, K., Kireeva, M., Osuch, M. , Sauquet, E., Stagge, J. H., Van Loon, A. F.
  Hydrology needed to manage droughts: the 2015 European case
  2016 Hydrological Processes, volume: 30, issue: 17, pages: 3097 - 3104
• Sprenger, M., Leistert, H., Gimbel, K., Weiler, M.
  Illuminating hydrological processes at the soil-vegetation-atmosphere interface with water stable isotopes
  2016 Reviews of Geophysics, volume: 54, issue: 3, page: 674–704
• Stahl, K., Kohn, I., Blauhut, V. , Urquijo, J., De Stefano, L., Acácio, V., Dias, S., Stagge, J. H., Tallaksen, L. M., Kampragou, E., Van Loon, A. F., Barker, L. J., Melsen, L. A., Bifulco, C., Musolino, D., de Carli, A. , Massarutto, A., Assimacopoulos, D., Van Lanen, H. A. J.
  Impacts of European drought events: insights from an international database of text-based reports
  2016 Nat. Hazards Earth Syst. Sci., volume: 16, pages: 801 - 819
• González Tánago, I., Urquijo, J., Blauhut, V. , Villarroya, F., De Stefano, L.
  Learning from experience: a systematic review of assessments of vulnerability to drought
  2016 Natural Hazards, volume: 80, issue: 2, pages: 951 - 973
• Hartmann, A., Kobler, J., Kralik, M., Dirnböck, T., Humer, F., Weiler, M.
  Model-aided quantification of dissolved carbon and nitrogen release after windthrow disturbance in an Austrian karst system
  2016 Biogeosciences, volume: 13, pages: 159 - 174
• Steinbrich, A., Leistert, H., Weiler, M.
  Model-based quantification of runoff generation processes at high spatial and temporal resolution.
  2016 Environmental Earth Sciences, volume: 75, issue: 1423, pages: 1 - 16
• Schuetz, T., Gascuel-Odoux, C., Durand, P., Weiler, M.
  Nitrate sinks and sources as controls of spatio-temporal water quality dynamics in an agricultural headwater catchment
  2016 Hydrology and Earth System Sciences, volume: 20, pages: 843 - 857
• Pohl, S., Steinbrich, A., Weiler, M.
  Pilotstudie: Validierung der Oberflächenabflüsse nach Starkregen durch RoGeR an einem Schadensereignis in Bonndorf im Juni 2015
  2016 , volume: IHF-Bericht No 153
• Pohl, S., Steinbrich, A., Weiler, M.
  Pilotstudie: Validierung der Oberflächenabflüsse nach Starkregen durch RoGeR für das Schadensereignis in Bretten im Juni 2015
  2016 , volume: IHF-Bericht No 154
• Hartmann, A.
  Putting the cat in the box: why our models should consider subsurface heterogeneity at all scales
  2016 WIREs Water, volume: 3, issue: 4, page: 478–486
• Hagedorn, F., Joseph, J., Peter, M., Luster, J., Pritsch, K., Geppert, U., Kerner, R., Molinier, V., Egli, S., Schaub, M., Liu, J.-F., Li, M., Sever, K., Weiler, M., Siegwolf, R. T. W. , Gessler, A., Arend, M.
  Recovery of trees from drought depends on belowground sink control
  2016 Nature Plants, volume: 2, issue: Article number: 16111, pages: 1 - 5
• Collins, K., Hannaford, J., Svoboda, M., Knutson, C., Wall, N., Bernadt, T., Crossman, N., Overton, I., Acreman, M., Bachmair, S., Stahl, K.
  Stakeholder Co-inquiries on Drought Impacts, Monitoring and Early Warning Systems
  2016 Bull. Amer. Meteor. Soc., volume: 97, page: ES217–ES220
• Berghuijs, W.R., Hartmann, A., Woods, R.A.
  Streamflow sensitivity to water storage changes across Europe
  2016 Geophys. Res. Lett., volume: 43, issue: 5, pages: 1980 - 1987
• Ries, F., Schmidt, S.
  Technical report on hydrological monitoring in semi-arid areas - Experiences from field work in the Middle East
  2016 Chair of Hydrology, University of Freiburg, volume: Series Paper 2
• Blume, T., van Meerveld, I., Weiler, M.
  The role of experimental work in hydrological sciences – insights from a community survey
  2016 Hydrological Sciences Journal, pages: 1 - 4
• Sprenger, M., Seeger, S., Blume, T., Weiler, M.
  Travel times in the vadose zone: Variability in space and time
  2016 Water Resources Research, volume: 52, issue: 8, page: 5727–5754

2015

• Hartmann, A., Gleeson, T., Rosolem, R., Pianosi, F., Wada, Y., Wagener, T.
  A large-scale simulation model to assess karstic groundwater recharge over Europe and the Mediterranean
  2015 Geoscientific Model Development, volume: 8, issue: 6, page: 1729–1746
• Fleig, A. K., Tallaksen, L. M., James, P., Hisdal, H., Stahl, K.
  Attribution of European precipitation and temperature trends to changes in synoptic circulation
  2015 Hydrol. Earth Syst. Sci., volume: 19, pages: 3093 - 3107
• Stagge, J.H., Tallaksen, L.M., Gudmundsson, L., van Loon, A., Stahl, K.
  Candidate Distributions for Climatological Drought Indices (SPI and SPEI)
  2015 International Journal of Climatology
• Wolters, W., Stahl, K., González Tánago, I., Andreu, J., Van Lanen, H.A.J., Kampragou, E., Davy, T.
  Discussing drought at the pan-European level: results from the 3rd pan-European Drought Dialogue Forum
  2015 , volume: 31
• Weiler, M., Beven, K.
  Do we need a Community Hydrological Model
  2015 Water Resources Research
• Gimbel, K. F., Felsmann, K., Baudis, M., Puhlmann, H., Gessler, A., Bruelheide, H., Kayler,Z., Ellerbrock, R. H., Ulrich, A, Welk, E., Weiler, M
  Drought in forest understory ecosystems – a novel rainfall reduction experiment
  2015 Biogeosciences Discuss., volume: 12, pages: 961 - 975
• Sprenger, M., Herbstritt, B., Weiler, M.
  Established methods and new opportunities for pore water stable isotope analysis
  2015 Hydrological Processes, volume: 29, issue: 25, pages: 5174 - 5192
• Sprenger, M., Volkmann, T.H.M., Blume, T., Weiler, M.
  Estimating flow and transport parameters in the unsaturated zone with pore water stable isotopes
  2015 , volume: 19, issue: 6, page: 2617–2635
• Bachmair, S., Kohn, I., Stahl, K.
  Exploring the link between drought indicators and impacts
  2015 Nat. Hazards Earth Syst. Sci., volume: 15, pages: 1381 - 1397
• Stagge, J.H., Rizzi, J., Tallaksen, L.M., Stahl, K.
  Future Meteorological Drought: Projections of Regional Climate Models for Europe
  2015 , volume: 25
• Witmer, F.P, Wolters, W., Van Lanen, H.A.J., Seneviratne, S.I., Assimacopoulos, D., De Stefano, L., Tallaksen, L.M., Massarutto, A., Stahl, K., Andreu, J., Rego, F.C., Seidl, I.
  Identification of Drought Messages for Policy Makers, Businesses and Citizens
  2015 , volume: 30
• Stoelzle, M., Weiler, M., Stahl, K., Morhard, A., Schuetz, T.
  Is there a superior conceptual groundwater model structure for baseflow simulation?
  2015 Hydrological Processes, volume: 29, issue: 6, pages: 1301 - 1313
• González Tánago, I., Urquijo, J., Blauhut, V., Villarroya, F., De Stefano, L.
  Learning from experience: a systematic review of assessments of vulnerability to drought
  2015 Nat. Hazards, volume: 80, issue: 2, pages: 951 - 973
• Blauhut, V., Stahl, K.
  Mapping Drought Risk in Europe
  2015 , volume: 27
• De Stefano, L., González Tánago, I., Ballesteros, M., Urquijo, J., Blauhut, V., Stagge, J.H, Stahl, K.
  Methodological approach considering different factors influencing vulnerability - pan-European scale
  2015 , volume: 26
• Gunkel, A., Shadeed, S., Hartmann, A., Wagener, T., Lange, J.
  Model signatures and aridity indices enhance the accuracy of water balance estimations in a data-scarce Eastern Mediterranean catchment
  2015 J. Hydrol. Reg. Stud., volume: 4, pages: 487 - 501
• Stagge, J.H., Kohn, I., Tallaksen, L.M., Stahl, K.
  Modeling drought impact occurrence based on meteorological drought indices in Europe
  2015 Journal of Hydrology - Special Issue, issue: 530, page: 37–50
• Schuetz, T., Gascuel-Odoux, C., Durand, P., Weiler, M.
  Nitrate sinks and sources as controls of spatio-temporal water quality dynamics in an agricultural headwater catchment
  2015 Hydrology and Earth System Sciences Discussions, volume: 12, pages: 8577 - 8614
• Gutowski, L., Olsson, O., Lange, J., Kümmerer, K.:
  Photolytic transformation products and biological stability of the hydrological tracer Uranine
  2015 Science of the Total Environment, volume: 533, page: 446–453
  
   
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• Gassmann, M., Olsson, O., Stamm, C., Weiler, M., Kümmerer, K.
  Physico-chemical characteristics affect the spatial distribution of pesticide and transformation product loss to an agricultural brook
  2015 Science of the Total Environment, volume: 532, pages: 733 - 743
• Staudinger, M., Weiler, M., Seibert, J.
  Quantifying sensitivity to droughts: an experimental modeling approach
  2015 Hydrology and Earth System Sciences, volume: 19, issue: 3, pages: 1371 - 1384
• Ries, F., Lange, J., Schmidt, S., Puhlmann, H., Sauter, M.
  Recharge estimation and soil moisture dynamics in a Mediterranean, semi-arid karst region
  2015 Hydrology and Earth System Sciences, volume: 19, pages: 1439 - 1456
• Stahl, K., Stagge, J.H., Bachmair, S., Blauhut, V., Rego, F.C., De Stefano, L., Dias, S., Gudmundsson, L., Gunst, L., Kohn, I., Van Lanen, H.A.J. , Urquijo Reguera, J., Tallaksen, L.M.
  Recommendations for indicators for monitoring and early-warning considering different sensitivities: pan-European scale
  2015 , volume: 28
• Hartmann, A., Mudarra, M., Marín, A., Andreo, B., Wagener, T.
  Relating Land Surface Information and Model Parameters for a Karst System in Southern Spain
  2015 Springer Berlin Heidelberg, volume: 1, page: 345–352
• Felsmann, K., Baudis, M., Gimbel, K., Kayler, Z. E., Ellerbrock, R. H., Bruehlheide, H.
  Soil Bacterial Community Structure Responses to Precipitation Reduction and Forest Management in Forest Ecosystems across Germany
  2015 PloS one, volume: 10, issue: 4
• Martini, E., Wollschläger, U., Kögler, S., Behrens, T., Dietrich, P., Reinstorf, F., Schmidt, K. , Weiler, M., Werban, U., Zacharias, S.
  Spatial and Temporal Dynamics of Hillslope-Scale Soil Moisture Patterns: Characteristic States and Transition Mechanisms
  2015 Vadose Zone Journal, volume: 14, issue: 4
• Garvelmann, J., Pohl, S., Weiler, M.
  Spatio-temporal controls of snowmelt and runoff generation during rain-on-snow events in a mid-latitude mountain catchment
  2015 Hydrological Processes, volume: 29, issue: 17, page: 3649–3664
• Von Sperber, C., Weiler, M., , Brüggemann, N.
  The effect of soil moisture, soil particle size, litter layer and carbonic anhydrase on the oxygen isotopic composition of soil-released CO2
  2015 European Journal of Soil Science, volume: 66, issue: 3, pages: 566 - 576
• Blauhut V., Gudmundsson, L., Stahl, K.
  Towards pan-European drought risk maps: quantifying the link between drought indices and reported drought impacts
  2015 Environ. Res. Lett., volume: 10, issue: 014008
  
   
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• Lange, Jens, Kopp, Benjamin Johannes, Bents, Matthias, Menzel, Lucas
  Tracing variability of runoff generation in mountainous permafrost of semi-arid northeastern Mongolia
  2015 Hydrological Processes, volume: 29, issue: 6, pages: 1046 - 1055
• Leibundgut, Ch.
  Wasserressourcen am Oberrhein in Geschichte, Gegenwart und Zukunft
  2015 Alemannisches Jahrbuch, volume: 61/62, pages: 163 - 195
• Schwerdtfeger, J., Gripp, S.W.S., Zeilhofer, P., Weiler, M.
  oupled Ground- and Space-Based Assessment of Regional Inundation Dynamics to Assess Impact of Local and Upstream Changes on Evaporation in Tropical Wetlands
  2015 Remote Sensing, volume: 7, issue: 8, pages: 9769 - 9795

2014

• Staudinger, M., Stahl, K., Seibert, J.
  A drought index accounting for snow.
  2014 Water Resources Research, volume: 50, issue: 10, page: 7861–7872
• Hartmann, A., Gleeson, T., Rosolem, R., Pianosi, F., Wada, Y., Wagener, T.
  A large-scale simulation model to assess karstic groundwater recharge over Europe and the Mediterranean
  2014 Geosci. Model Dev. Discuss., volume: 8, issue: 6, page: 1729–1746
• Hartmann, A., Gleeson, T., Rosolem, R., Pianosi, F., Wada, Y., Wagener, T.
  A simulation model to assess groundwater recharge over Europe’s karst regions
  2014 Geosci. Model Dev. Discuss., volume: 7, issue: 6, page: 7887–7935
• Fleig, A. K., Tallaksen, L. M., James, P., Hisdal, H., Stahl, K.
  Attribution of European precipitation and temperature trends to changes in circulation types
  2014 Hydrology and Earth System Sciences Discussion, volume: 11, pages: 12799 - 12831
• Volkmann, T. H. M., Weiler, M.
  Continual in situ monitoring of pore water stable isotopes in the subsurface
  2014 Hydrology and Earth System Sciences, volume: 18, pages: 1819 - 1833
• Gimbel, K. F., Felsmann, K., Baudis, M., Puhlmann, H., Gessler, A., Bruelheide, H., Kayler, Z., Ellerbrock, R. H., Ulrich, A., Welk, E, Weiler, M.
  Drought in forest understory ecosystems– a novel rainfall reduction experiment
  2014 Biogeosciences Discuss., volume: 11, page: 14319–14358
• Leibundgut, Christian, Kohn, Irene
  European Traditional Irrigation in Transition Part I: Irrigation in Times Past - A historic land use practice across Europe
  2014 Irrigation and Drainage, volume: 63, issue: 3, page: 273–293
• Leibundgut, Christian, Kohn, Irene
  Europen Traditional Irrigation in Transition Part II: Traditional Irrigation in our Time—Decline, Rediscovery and Restoration Perspectives
  2014 Irrigation and Drainage, volume: 63, issue: 3, page: 294–314
• Kohn, Irene, Freudiger, Daphné , Rosin, Klemens, Stahl, Kerstin, Weiler, Markus, Belz, J U
  Extremjahr 2011: Dokumentation, Einordnung, Ursachen und Zusammenhänge
  2014 Bundesanstalt für Gewässerkunde, volume: 29
• Gudmundsson, L., Van Loon, A.F., Tallaksen, L.M., Seneviratne, S.I, Stagge, J.H., Stahl, K., Van Lanen, H.A.J.
  Guidelines for monitoring and early warning of drought in Europe
  2014 , volume: 21
• Baudis, M., Ellerbrock, R. H., Felsmann, K., Gessler, A., Gimbel, K. F., Kayler, Z.
  Intraspecific differences in responses to rainshelter-induced drought and competition of Fagus sylvatica L. across Germany
  2014 Forest Ecology and Management, volume: 330, page: 283–293
• Schwerdtfeger, J., Johnson, M. S., Couto, E. G., Amorim, R. S. S., Sanches, L., Campelo Jr., J. H., Weiler, M.
  Inundation and groundwater dynamics for quantification of evaporative water loss in tropical wetlands.
  2014 Hydrology and Earth System Sciences Discussion, volume: 18, issue: 11, pages: 4407 - 4022
• Stoelzle, M , Weiler, M , Stahl, K, Morhard, A, Schuetz, T
  Is there a superior conceptual groundwater model structure for baseflow simulation?
  2014 Hydrological Processes
• Hartmann, A., Goldscheider, N., Wagener, T., Lange, J., Weiler, M.
  Karst water resources in a changing world: Review of hydrological modeling approaches
  2014 Reviews of Geophysics
• Freudiger, D., Kohn, I., Stahl, K., Weiler, M.
  Large-scale analysis of changing frequencies of rain-on-snow events with flood-generation potential
  2014 Hydrology and Earth System Sciences, volume: 18, pages: 2695 - 2709
• Hartmann, A., Mudarra, M., Andreo, B., Marín, A., Wagener, T., Lange, J.
  Modeling spatiotemporal impacts of hydroclimatic extremes on groundwater recharge at a Mediterranean karst aquifer.
  2014 Water Resources Research, volume: 50, issue: 8, page: 6507–6521
• Steinbrich, A., Leistert, H., Weiler, M.
  Modellierung und Gefährdungspotential von wild abfließendem Wasser
  2014 , volume: IHF-Bericht No 151
• Kohn, I., Rosin, K., Freudiger, D., Belz, J.U., Stahl, K., Weiler, M.
  Niedrigwasser in Deutschland 2011
  2014 Hydrologie und Wasserbewirtschaftung, volume: 58, issue: 1, pages: 4 - 17
• Rimmer, A., Hartmann, A.
  Optimal hydrograph separation filter to evaluate transport routines of hydrological models.
  2014 Journal of Hydrology, volume: 514, page: 249–257
• Pohl, S., Garvelmann, J., Wawerla, J., Weiler, M.
  Potential of a low-cost sensor network to understand the spatial and temporal dynamics of a mountain snow cover
  2014 Water Resources Research, volume: 50, page: 2533–2550
• Ries, F., Lange, J., Schmidt, S., Puhlmann, H., Sauter, M.,
  Recharge estimation and soil moisture dynamics in a Mediterranean karstaquifer
  2014 Hydrology and Earth System Sciences Discussion, volume: 11, issue: 7, page: 8803–8844
• Seeger, S., Weiler, M
  Reevaluation of transit time distributions, mean transit times and their relation to catchment topography
  2014 Hydrology and Earth System Sciences Discussion, volume: 18, pages: 4751 - 4771
• Sohrt, J., Ries, F., Sauter, M., Lange, J.
  Significance of preferential flow at the rock soil interface in a semi-arid karst environment
  2014 Catena, volume: 123, page: Pages 1–10
• Tallaksen, Lena M., Stahl, Kerstin
  Spatial and temporal patterns of large-scale droughts in Europe: Model dispersion and performance
  2014 Geophysical Research Letters, page: GL058573
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  Abstract

  This study explores the performance of a suite of off-line, global (hydrological and land surface) models in mapping spatial and temporal patterns of large-scale hydrological droughts in Europe from simulated runoff in the period 1963–2000. Consistent model behavior was found for annual variability in mean drought area, whereas high model dispersion was revealed in the weekly evolution of contiguous area in drought and its annual maximum. Comparison with nearly three hundred catchment-scale streamflow observations showed an overall tendency to overestimate the number of drought events and hence underestimate drought duration, whereas persistence in drought-affected area (weekly mean) was underestimated, noticeable for one group of models. The high model dispersion in temporal and spatial persistence of drought identified implies that care should be taken when analyzing drought characteristics from only one or a limited number of models unless validated specifically for hydrological drought.
• Tallaksen, L.M., Stahl, K.
  Spatial and temporal patterns of large-scale droughts in Europe: model dispersion and performance
  2014 Geophys. Res. Letters, volume: 41, issue: 2, pages: 429 - 434
• Stahl, K., Blauhut, V., Kohn, I., De Stefano, L., Dias, S., Urquijo, J., Tallaksen, L.M., Van Lanen, H.A.J., Wolters, W.
  Stakeholder views on drought impacts and drought risk maps at the pan-European scale results from the 2nd pan-European Drought Dialogue Forum
  2014 , volume: 17
• Stoelzle, M, Stahl, K, Morhard, A, Weiler, M
  Streamflow sensitivity to drought scenarios in catchments with different geology
  2014 Geophysical Research Letters
• Mueller, M.H., Alaoui, A., Kuells, C., Leistert, H., Meusburger, K., Stumpp, C., Weiler, M., Alewell, C.
  Tracking water pathways in steep hillslopes by ?18 O depth profiles of soil water
  2014 Journal of Hydrology - Special Issue, volume: 519, page: 340–352
• Allen D.M., Stahl K., Whitfield P.H., Moore R.D.
  Trends in groundwater levels in British Columbia
  2014 Can Water Resour J, volume: 39, pages: 15 - 31
• Garvelmann, J., Pohl, S., Weiler, M.
  Variability of observed energy fluxes during rain-on-snow and clear sky snowmelt in a mid-latitude mountain environment
  2014 Journal of Hydrometeorology, volume: 15, issue: 3, pages: 1220 - 1237
• Sprenger, M. , Volkmann, T.H.M., Blume, T., Weiler, M.
  stimating flow and transport parameters in the unsaturated zone with pore water stable isotopes
  2014 Hydrology and Earth System Sciences Discussion, volume: 11, pages: 11203 - 11245

2013

• Stagge, J.H., Tallaksen, L.M., Kohn, I., Stahl, K., van Loon, A.
  A European Drought Reference (EDR) Database: design and Online Implementation
  2013 , volume: 12
• Stoelzle, M., Stahl, K., Weiler, M.
  Are streamflow recession characteristics really characteristic?
  2013 Hydrology and Earth System Sciences, Copernicus Publications, volume: 17, issue: 2, pages: 817 - 828
• Smith, R.S., Moore, R.D., Weiler, M., Jost, G.
  Controls on groundwater response and runoff source area dynamics in a snowmelt-dominated montane catchment
  2013 Hydrol. Earth Syst. Sci. Discuss, volume: 10, issue: 2, pages: 2549 - 2600
• Stähli, M., Kruse, S., Fundel, F., Zappa, M., Stahl, K., Bernhard, L., Seidl, I.
  Drought.ch - auf dem Weg zu einer Trockenheits-Informationsplattform für die Schweiz
  2013 Wasser Energie Luft, volume: 2/2013, pages: 117 - 121
• Schwerdtfeger, J.,, Weiler, M.,, Johnsonc, M.S.,, Coutod, E.G.
  Estimating Water Balance Components of Tropical Wetland Lakes in the Pantanal Dry Season, Brazil
  2013 Hydrological Sciences Journal, volume: 59, issue: 12, pages: 2158 - 2172
  
   
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• Jackisch, N., Brendt, Th., Weiler, M., Lange, J.
  Evaluierung der Regenwasserbewirtschaftung im Vaubangelände - unter besonderer Berücksichtigung von Gründächern und Vegetation, Endbericht
  2013 , issue: Projektnummer: 2009-09
• Garvelmann, J., Pohl, S., Weiler, M.
  From observation to the quantification of snow processes with a time-lapse camera network
  2013 Hydrology and Earth System Sciences, Copernicus Publications, volume: 17, issue: 4, pages: 1415 - 1429
• Bachmair, Sophie, Weiler, Markus
  Interactions and connectivity between runoff generation processes of different spatial scales
  2013 Hydrological Processes
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  Abstract

  Monitoring runoff generation processes in the field is a prerequisite for developing conceptual hydrological models and theories. At the same time, our perception of hydrological processes strongly depends on the spatial and temporal scale of observation. Therefore, the aim of this study is to investigate interactions between runoff generation processes of different spatial scales (plot scale, hillslope scale, and headwater scale). Different runoff generation processes of three hillslopes with similar topography, geology and soil properties, but differences in vegetation cover (grassland, coniferous forest, and mixed forest) within a small v-shaped headwater were measured: water table dynamics in wells with high spatial and temporal resolution, subsurface flow (SSF) of three 10 m wide trenches at the bottom of the hillslopes subdivided into two trench sections each, overland flow at the plot scale, and catchment runoff. Bachmair et al. () found a high spatial variability of water table dynamics at the plot scale. In this study, we investigate the representativity of SSF observations at the plot scale versus the hillslope scale and vice versa, and the linkage between hillslope dynamics (SSF and overland flow) and streamflow. Distinct differences in total SSF within each 10 m wide trench confirm the high spatial variability of the water table dynamics. The representativity of plot scale observations for hillslope scale SSF strongly depends on whether or not wells capture spatially variable flowpaths. At the grassland hillslope, subsurface flowpaths are not captured by our relatively densely spaced wells (3 m), despite a similar trench flow response to the coniferous forest hillslope. Regarding the linkage between hillslope dynamics and catchment runoff, we found an intermediate to high correlation between streamflow and hillslope hydrological dynamics (trench flow and overland flow), which highlights the importance of hillslope processes in this small watershed. Although the total contribution of SSF to total event catchment runoff is rather small, the contribution during peak flow is moderate to substantial. Additionally, there is process synchronicity between spatially discontiguous measurement points across scales, potentially indicating subsurface flowpath connectivity. Our findings stress the need for (i) a combination of observations at different spatial scales, and (ii) a consideration of the high spatial variability of SSF at the plot and hillslope scale when designing monitoring networks and assessing hydrological connectivity. Copyright © 2013 John Wiley & Sons, Ltd.
• Klaus, J., Zehe, E., Elsner, M., Külls, C., McDonnell, J. J.
  Macropore flow of old water revisited: experimental insights from a tile-drained hillslope
  2013 Hydrology and Earth System Sciences, Copernicus Publications, volume: 17, issue: 1, pages: 103 - 118
• Gassmann, M., Stamm, C., Olsson, O., Lange. J., Kümmerer, K., Weiler, M.
  Model-based estimation of pesticides and transformation products and their export pathways in a headwater catchment
  2013 Hydrology and Earth System Sciences
• Hartmann, A., Weiler, M., Wagener, T., Lange, J., Kralik, M., Humer, F., Mizyed, N., Rimmer, A., Barberá, J. A., Andreo, B., Butscher, C., Huggenberger, P.
  Process-based karst modelling to relate hydrodynamic and hydrochemical characteristics to system properties
  2013 Hydrology and Earth System Sciences Discussion, Copernicus Publications, volume: 10, issue: 3, pages: 2835 - 2878
• Hartmann, A., Barberá, J.A., Lange, J., Andreo, B., Weiler, M.
  Progress in the hydrologic simulation of time variant recharge areas of karst systems – Exemplified at a karst spring in Southern Spain
  2013 Advances in Water Resources, volume: 54, issue: 0, pages: 149 - 160
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  Abstract

  A specific characteristic of karst systems is the occurrence of time variant recharge areas. In our study we present a new type of hydrological karst model and a new calibration approach both considering this specific characteristic. The new model type considers the spatial variability of karst system properties by distribution functions, and is compared to a simple reservoir model. Both models are applied to a karst system in Southern Spain where objective functions applied on hydrodynamic and hydrochemical information helped to determine model parameters playing a role for hydrodynamic response. Thereafter, the recharge area is determined separately for individual hydrological years and for the entire time series by calibrating the model to match the water balance. We show that hydrochemical information is crucial to find a reasonable set of parameters for both models. Considering different hydrological years, we find that the recharge area is changing significantly (from 28 to 53 km2). The newly developed model is able to reproduce this variation and provide acceptable simulation results for the entire time series of available data. The classic reservoir model shows inferior performance concerning hydrodynamics and fails to reproduce the water balance because it does not consider variations of recharge area. Our calibration approach allows identifying a variable recharge area and our new model is able to reproduce its variability. Hence we obtain a more realistic system representation, which can be of high significance when models are used for prediction, i.e. beyond the conditions they were calibrated, e.g. for land-use or climate change scenarios.
• Van Lanen, H.A.J., Alderlieste, M.A.A., Acacio, A., Andreu, J., Garnier, E., Gudmundsson, L., Haro Monteagudo, D., Lekkas, D., Paredes, J., Solera, A., Assimacopoulos, D., Rego, F., Seneviratne, S., Stahl, K., Tallaksen, L.M.
  Quantitative analysis of historic droughts in selected European case study areas
  2013 , volume: 8
• Dietermann, N., Weiler, M.
  Spatial distribution of stable water isotopes in alpine snow cover
  2013 Hydrology and Earth System Sciences Discussion, Copernicus Publications, volume: 10, issue: 3, pages: 2641 - 2664
• Hannaford, J., Buys, G., Stahl, K., Tallaksen, L. M.
  The influence of decadal-scale variability on trends in long European streamflow records
  2013 Hydrology and Earth System Sciences, Copernicus Publications, volume: 17, issue: 7, pages: 2717 - 2733
• Leibundgut, C., Vonderstrass, I.
  Traditionelle Bewässerung als Kulturerbe Europas
  2013 Geographische Rundschau, volume: 65, issue: 7-8, pages: 8 - 17
• Durst, Romy, Imfeld, Gwenaël, Lange, Jens
  Transport of pesticides and artificial tracers in vertical-flow lab-scale wetlands
  2013 Water Resources Research, pages: n/a - n/a
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  Abstract

  Wetland systems can be hydrologically connected to a shallow aquifer and intercept upward flow of pesticide-contaminated water during groundwater discharge. However, pesticide transport and attenuation through wetland sediments (WSs) intercepting contaminated water is rarely evaluated quantitatively. The use of artificial tracers to evaluate pesticide transport and associated risks is a fairly new approach that requires evaluation and validation. Here we evaluate during 84 days the transport of two pesticides (i.e., isoproturon (IPU) and metalaxyl (MTX)) and three tracers (i.e., bromide (Br), uranine (UR), and sulforhodamine B (SRB)) in upward vertical-flow vegetated and nonvegetated lab-scale wetlands. The lab-scale wetlands were filled with outdoor WSs and were continuously supplied with tracers and the pesticide-contaminated water. The transport of IPU and UR was characterized by high solute recovery (approximately 80%) and low retardation compared to Br. The detection of desmethylisoproturon in the wetlands indicated IPU degradation. SRB showed larger retardation (>3) and lower recovery (approximately 60%) compared to Br, indicating that sorption controlled SRB transport. MTX was moderately retarded (approximately 1.5), and its load attenuation in the wetland reached 40%. In the vegetated wetland, preferential flow along the roots decreased interactions between solutes and sediments, resulting in larger pesticide and tracer recovery. Our results show that UR and IPU have similar transport characteristics under the tested subsurface-flow conditions, whereas SRB may serve as a proxy for less mobile and more persistent pesticides. Since UR and SRB are not significantly affected by degradation, their use as proxies for fast degrading pollutants may be limited. We anticipate our results to be a starting point for considering artificial tracers for investigating pesticide transport in environments at groundwater/surface-water interfaces.
• Leibundgut, C., Vonderstraß, I.
  Zeitenwende im Umweltschutz
  2013 Aqua Viva: die Zeitschrift für Gewässerschutz, volume: 1, pages: 4 - 10

2012

• Stahl, K., Blauhut, V., Kohn, I., Acácio, V., Assimacopoulos, D., Bifulco, C., De Stefano, L., Dias, S., Eilertz, D., Frielingsdorf, B., Jahr Hegdahl, T., Kampragou, E., Kourentzis, V., Melsen, L., van Lanen, H.A.J., van Loon, A.F., Massarutto, A., Musolino, D., de Paoli, L., Senn, L., Stagge, J.H., Tallaksen, L.M., Urquijo, J.
  A European Drought Impact Report Inventory (EDII): Design and Test for Selected Recent Droughts in Europe
  2012 DROUGHT-R&SPI Technical Report, volume: 3, page: 23
• Hartmann, Andreas, Lange, Jens, Vivó Aguado, Àngela, Mizyed, Numan, Smiatek, Gerhard, Kunstmann, Harald
  A multi-model approach for improved simulations of future water availability at a large Eastern Mediterranean karst spring
  2012 Journal of Hydrology, volume: 468–469, issue: 0, pages: 130 - 138
  » show abstract« hide abstract
  Abstract

  Summary Recent studies identified the Mediterranean as a region particularly vulnerable to climate change. Since a large fraction of the region’s water originates from karst aquifers, information about their future water availability is important for sustainable water management. This study presents an ensemble of 50 model chains considering five different realisations of the A1B ECHAM5 and HadCM3 climate projections, two different averaging methods to transfer the climate variables to the system scale and five different hydrological models that represent reasonable conceptualizations of the karst system. The ensemble is applied to Faria spring, a large Eastern Mediterranean karst spring in the West Bank. We show that for the near future (2021–2051) variability resulting from the different climate change projections and five different models is too large to draw conclusions on any significant change. In the remote future (2068–2098), variability decreases and our simulations suggest a decrease of water availability of −15% to −30%. We also assess the impact of recent pumping activities by running our hydrological models with recently measured data. There is a strong indication that the spring, which dried out in 2007, would have still yielded significant amounts of water if groundwater extractions had been limited. This calls for a better management of groundwater abstractions to meet future water needs in this drought-prone Mediterranean region.
• Hartmann, A., Lange, J., Vivó Aguado, À., Mizyed, N., Smiatek, G., Kunstmann, H.
  A multi-model approach for improved simulations of future water availability at a large Eastern Mediterranean karst spring.
  2012 Journal of Hydrology - Special Issue, volume: 468-469, page: 130–138
• Hartmann, A., Lange, J., Weiler, M., Arbel, Y., Greenbaum, N.
  A new approach to model the spatial and temporal variability of recharge to karst aquifers
  2012 Hydrology and Earth System Sciences, Copernicus Publications, volume: 16, issue: 7, pages: 2219 - 2231
• Hartmann, A., Lange, J., Weiler, M., Arbel, Y., Greenbaum, N.
  A new approach to model the spatial and temporal variability of recharge to karst aquifers.
  2012 Hydrology and Earth System Sciences, volume: 16, issue: 7, page: 2219–2231
• Garvelmann, J., Külls, C., Weiler, M.
  A porewater-based stable isotope approach for the investigation of subsurface hydrological processes
  2012 Hydrology and Earth System Sciences, Copernicus Publications, volume: 16, issue: 2, pages: 631 - 640
• Steinbrich, A., Weiler, M.
  Abschlussbericht zu den systematischen Untersuchungen zum N-A-Modell DROGen
  2012 , volume: IHF-Bericht No 150
• de Stefano, L., Duncan, J., Dinar, S., Stahl, K., Strzepek, K.M., Wolf, A.T.
  Climate change and the institutional resilience of international river basins
  2012 Journal of Peace Research, volume: 49, issue: 1, pages: 193 - 209
• Sambaraju, K. R., Carroll, A. L., Zhu, J., Stahl, K., Moore, R. D.
  Climate change could alter the distribution of mountain pine beetle outbreaks in western Canada
  2012 Ecography, volume: 35, issue: 3, pages: 211 - 223
• Herbstritt, Barbara, Gralher, Benjamin, Weiler, Markus
  Continuous in situ measurements of stable isotopes in liquid water
  2012 Water Resources Research, AGU, volume: 48, issue: 3, page: W03601
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  Abstract

  We developed a method to measure in situ the isotopic composition of liquid water with minimal supervision and, most important, with a temporal resolution of less than a minute. For this purpose a microporous hydrophobic membrane contactor (Membrana) was combined with an isotope laser spectrometer (Picarro). The contactor, originally designed for degassing liquids, was used with N2 as a carrier gas in order to transform a small fraction of liquid water to water vapor. The generated water vapor was then analyzed continuously by the Picarro analyzer. To prove the membrane's applicability, we determined the specific isotope fractionation factor for the phase change through the contactor's membrane across an extended temperature range (8°C&#8211;21°C) and with different waters of known isotopic compositions. This fractionation factor is needed to subsequently derive the liquid water isotope ratio from the measured water vapor isotope ratios. The system was tested with a soil column experiment, where the isotope values derived with the new method corresponded well (R2 = 0.998 for &#948;18O and R2 = 0.997 for &#948;2H) with those of liquid water samples taken simultaneously and analyzed with a conventional method (cavity ring-down spectroscopy). The new method supersedes taking liquid samples and employs only relatively cheap and readily available components. This makes it a relatively inexpensive, fast, user-friendly, and easily reproducible method. It can be applied in both the field and laboratory wherever a water vapor isotope analyzer can be run and whenever real-time isotope data of liquid water are required at high temporal resolution.
• Baram, S., Ronen, Z., Kurtzman, D., Küells, C., Dahan, O.
  Desiccation-crack-induced salinization in deep clay sediment
  2012 Hydrology and Earth System Sciences Discussion, volume: 9, issue: 11, pages: 13155 - 13189
• Gassmann, Matthias, Lange, Jens, Schuetz, Tobias
  Erosion modelling designed for water quality simulation
  2012 Ecohydrology, John Wiley & Sons, Ltd, volume: 5, issue: 3, pages: 269 - 278
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  Abstract

  Water quality modelling often requires the simulation of erosion and sediment transport for sorptive pollutants at high temporal resolution. This paper introduces a parsimonious erosion and sediment transport model adapted to the needs of water quality modelling called ZIN-Sed. Using a kinetic-energy-of-rainfall erosion approach and an empirical transport capacity equations of overland flow, the model can mainly be parameterized by measurements, observations and literature values and just requires little calibration. It is based on the hydrological surface flow model ZIN and was tested in the 1.8 km2 Loechernbach catchment in south-western Germany. High resolution measurements of suspended sediment concentration (SSC) by turbidity measurements (eight events) provided an opportunity to validate the model on a short-timestep base. To broaden the validation database, a calibrated MUSLE (Modified Universal Soil Loss Equation) was used to estimate sediment totals of additional 28 events. The model realistically simulated both measured SSCs and estimated sediment totals and arrived at high Nash-Sutcliffe efficiencies (up to 0.85) and low RMSEs. Copyright © 2011 John Wiley & Sons, Ltd.
• Breña Naranjo, J. A., Stahl, K., Weiler, M.
  Evapotranspiration and land cover transitions: long term watershed response in recovering forested ecosystems
  2012 Ecohydrology, volume: 5, issue: 6, pages: 721 - 732
• Stahl, K., Tallaksen, L. M., Hannaford, J., van Lanen, H. A. J.
  Filling the white space on maps of European runoff trends: estimates from a multi-model ensemble
  2012 Hydrology and Earth System Sciences, Copernicus Publications, volume: 16, issue: 7, pages: 2035 - 2047
• Kura,, Piotr K., Alila, Younes, Weiler, Markus
  Forest harvesting effects on the magnitude and frequency of peak flows can increase with return period
  2012 Water Resources Research, AGU, volume: 48, issue: 1, page: W01544
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  Abstract

  Paired watershed studies have limited researchers wishing to disentangle road and harvesting effects on peak flows or to study management schemes other than the existing scenario. The outcomes of many paired watershed studies examining peak flows have also recently been challenged since only an approach that pairs peak flows by frequency can adequately evaluate the effects of harvesting on peak flows. This study takes advantage of a model that has been developed and extensively tested at a site containing a rich set of internal catchment process observations to examine the isolated and combined effects of roads and harvesting on the peak flow regime of a snow-dominated catchment for return periods of up to 100 years. Contrary to the prevailing perception in forest hydrology, the effects of harvesting are found to increase with return period, which is attributable to the uniqueness of peak flow runoff generation processes in snow-dominated catchments. Planned harvesting (50% harvest area) is found to have a significant effect (9%&#8211;25% over control) on peak flows with recurrence intervals ranging 10&#8211;100 years. Peak flow frequency increases after harvesting increase with return period, with the largest events (100 year) becoming 5&#8211;6.7 times more frequent, and medium-sized events (10 year) becoming 1.7&#8211;2 times more frequent. Such changes may have substantial ecological, hydrological, and geomorphological consequences within the watershed and farther downstream. Study findings suggest that peak flow regimes are fairly tolerant to the current level of harvesting in this particular watershed but that further harvesting may affect this element significantly.
• Bachmair, S., Weiler, M.
  Hillslope characteristics as controls of subsurface flow variability
  2012 Hydrology and Earth System Sciences Discussion, Copernicus Publications, volume: 9, issue: 6, pages: 6889 - 6934
• Hartmann, Andreas, Kralik, Martin, Humer, Franko, Lange, Jens, Weiler, Markus
  Identification of a karst system’s intrinsic hydrodynamic parameters: upscaling from single springs to the whole aquifer
  2012 Environmental Earth Sciences, Springer-Verlag, volume: 65, issue: 8, pages: 2377 - 2389
• Hartmann, A., Kralik, M., Humer, F., Lange, J., Weiler, M.
  Identification of a karst system’s intrinsic hydrodynamic parameters: upscaling from single springs to the whole aquifer.
  2012 Environmental Earth Sciences, volume: 65, issue: 8, page: 2377–2389
• Bachmair, S., Weiler, M., Troch, P. A.
  Intercomparing hillslope hydrological dynamics: Spatio-temporal variability and vegetation cover effects
  2012 Water Resources Research, AGU, volume: 48, issue: 5, page: W05537
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  Abstract

  Generalizable process knowledge on hillslope hydrological dynamics is still very poor, yet indispensable for numerous theoretical and practical applications. To gain insight into the organization of hillslope hydrological dynamics we intercompared 90 observations of shallow water table dynamics at three neighboring large-scale (33 × 75 m) hillslopes with similar slope, aspect, curvature, geologic, and pedologic properties but differences in vegetation cover (grassland, coniferous forest, and mixed forest) over a time period of 9 months. High-resolution measurements of water table fluctuations, rainfall, and discharge in the creek at the foot of all hillslopes allowed a good system characterization. The aim of this study was to explore the spatio-temporal variability of water table fluctuations within and between hillslopes, the effect of event and antecedent characteristics on the observed dynamics, and how the hillslope subsurface flow (SSF) response is reflected in the runoff response. To intercompare the SSF behavior we conducted an event-based analysis of the percentage of well activation, several metrics characterizing the shape and timing of the water table response curves, rainfall characteristics, antecedent wetness conditions, and several runoff response metrics. The analysis reveals that there are distinct differences in SSF response between the grassland hillslope and the forested hillslopes, with a lower frequency of well activation and absolute water table rise at the grassland hillslope. Second, spatial patterns of water table dynamics differ between wet fall/winter/spring (predominantly saturation of the lower part of the hillslope, weaker water table response, and slower response times) and dry summer conditions (whole-hillslope activation but higher spatial variability, generally stronger water table dynamics, and quicker response times). The observed seasonally changing water table dynamics suggest the development of a preferential flow network during high-intensity rainstorms under dry summer conditions. Third, catchment runoff is strongly driven by hillslope dynamics, yet contrasting hydrographs during events with similar hillslope dynamics indicate the influence of additional processes. Overall, the observed high spatio-temporal variability of seemingly homogeneous hillslopes calls for rethinking of current monitoring strategies and developing and testing new conceptual models of hillslope hydrologic processes.
• Wagener, T., Kelleher, C., Weiler, M., McGlynn, B., Gooseff, M., Marshall, L., Meixner, T., McGuire, K., Gregg, S., Sharma, P., Zappe, S.
  It takes a community to raise a hydrologist: the Modular Curriculum for Hydrologic Advancement (MOCHA)
  2012 Hydrology and Earth System Sciences Discussion, Copernicus Publications, volume: 9, issue: 2, pages: 2321 - 2356
• Schuetz, Tobias, Weiler, Markus, Lange, Jens
  Multitracer assessment of wetland succession: Effects on conservative and nonconservative transport processes
  2012 Water Resources Research, AGU, volume: 48, issue: 6, page: W06538
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  Abstract

  Because of emerging vegetation and sedimentation processes, the succession of wetlands is a dynamic process. Hence, a noticeable impact on the functioning and the efficiency of constructed treatment wetlands regarding solute retention can be expected. Within 5 months a reduction of active wetland volume, a decrease of light decay, and an increase of sorption capacity were observed using four multitracer experiments in a newly established constructed wetland. Tracer breakthrough curves of conservative and nonconservative tracers were analyzed with the help of a transient storage model. The model characterized the impact of vegetation development and sediment accumulation on solute transport properties. Three different tracers allowed an assessment of wetland hydraulics, sorption processes, and light impact on photodegradable solutes. Finally, the exemplary transport prediction of a fourth, independent tracer that was both photodegradable and sorptive demonstrated a cost-efficient technique to determine the influence of succession processes on treatment efficiency.
• Gunkel, A., Lange, J.
  New Insights Into The Natural Variability of Water Resources in The Lower Jordan River Basin
  2012 Water Resources Management, volume: 26, issue: 4, pages: 963 - 980
• Viviroli, D., Schädler, B., Schmocker-Fackel, P., Weiler, M., Seibert, J.
  On the risk of obtaining misleading results by pooling streamflow data for trend analyses
  2012 Water Resources Research, AGU, volume: 48, issue: 5, page: W05601
  » show abstract« hide abstract
  Abstract

  Floods have broad impacts on nature, society, and the economy. The frequency and intensity of flood events are generally believed to increase with the anticipated changes in temperature and precipitation. Trend analyses are important tools to quantify these changes, but often, they provide inconclusive results, partly because of the limited data availability. One way to overcome this limitation is to pool data from different gauging stations. However, pooling data from different stations may lead to misleading results. For example, using pooled flood data Allamano et al. (2009a) found a considerable increase of flooding risks for Switzerland. Here we demonstrate that the previous finding of increased flooding risks was an artifact of the pooling of stations and the fact that the longer time series came from larger catchments, which tend to have lower values for specific peak flows than smaller catchments. Our results demonstrate the risk of obtaining incorrect statistical conclusions when statistical analyses and data selection are not considered with due care.
• Puhlmann, Heike, von Wilpert, Klaus
  Pedotransfer functions for water retention and unsaturated hydraulic conductivity of forest soils
  2012 Journal of Plant Nutrition and Soil Science, WILEY-VCH Verlag, volume: 175, issue: 2, pages: 221 - 235
  » show abstract« hide abstract
  Abstract

  The hydraulic properties of soils, i.e., their ability to store and conduct water, mainly govern the availability of soil water for plants. Information on the hydraulic properties is needed, e.g., for the quantification of drought risk at a given site. Furthermore, knowledge of the water transport is the precondition for the estimation of element fluxes in the soil, e.g., when predicting element leaching from the root zone to the groundwater. For forest soils, only few systematic investigations of their hydraulic properties exist. Within the 2nd forest-soil survey of Germany, soil samples were taken along a regular 8 km × 8 km grid in the forests of the State of Baden-Württemberg and the hydraulic properties were estimated in the laboratory by multistep outflow experiments. Besides the soil-hydraulic measurements, numerous additional soil chemical and physical analyses were carried out and comprehensive profile descriptions were compiled and integrated in a hydraulic database. Based on this database, multiple-linear-regression techniques were used to develop pedotransfer functions for the water-retention curve and the unsaturated-hydraulic-conductivity curve using the parametric models of Mualem/van-Genuchten. Our work fills a gap since to our knowledge, no pedotransfer functions for the unsaturated hydraulic conductivity for forest soils exist so far. The predictive accuracy of the established pedotransfer functions, both for the water-retention curve and the hydraulic-conductivity curve, is in the range of (and in some cases better than) other published pedotransfer functions that were mostly derived for agricultural soils.
• Lange, J., Husary, S., Gunkel, A., Bastian, D., Grodek, T.
  Potentials and limits of urban rainwater harvesting in the Middle East
  2012 Hydrology and Earth System Sciences, volume: 16, issue: 3, pages: 715 - 724
• Lange, Jens, Haensler, Andreas
  Runoff generation following a prolonged dry period
  2012 Journal of Hydrology, volume: 464–465, issue: 0, pages: 157 - 164
  » show abstract« hide abstract
  Abstract

  Summary Several techniques were chosen to study changes in the hydrological response of a 1.53 km2 forest headwater to the exceptional climatic situation in summer 2005, when an intense early summer drought was followed by a wet summer. Nine consecutive after-drought runoff events were investigated. Hydrograph separation by electrical conductivity and direct observations of streamflow temperature suggested that immediately after the drought, storm runoff generation was dominated by event water, predominantly from the surface (permanent saturated areas and forest roads). Only during following events did subsurface runoff components regain their importance, causing higher fractions of pre-event water and a longer term increase of baseflow. This was manifested by increasing fractions of delayed flow per event and by smoother recession limbs of event hydrographs. Deep soil moisture sensors showed a retarded response to after-drought rainfall. In hillslope springs above 510 m, an almost contemporaneous, delayed increase of nitrate concentrations was found. Water quality data from the stream permitted insights into catchment scale runoff generation processes. Already in the very first water sample after the drought, diluted silica and enriched 18O-isotopes documented the importance of event water. One week later, suddenly increasing nitrate concentrations suggested the resumed participation of soil pathways, and hence subsurface components, in runoff generation after the drought. Thus, nitrate traced the after-drought transition from a surface- to a subsurface dominated runoff response, which soil moisture data had already indicated.
• Schuetz, Tobias, Weiler, Markus, Lange, Jens, Stoelzle, Michael
  Two-dimensional assessment of solute transport in shallow waters with thermal imaging and heated water
  2012 Advances in Water Resources, volume: 43, issue: 0, pages: 67 - 75
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  Abstract

  The two-dimensional distribution of flow velocities in shallow waters is one of the governing factors for solute transport processes. Thus, a direct and simple experimental method to spatially assess mean flow velocity and dispersion could improve the prediction of solute transport. In an experimentally constructed wetland we identified these variables on the basis of highly resolved spatial datasets obtained by a novel tracer approach: we observed slug injections of heated water with hand-held thermographic systems. Adding NaCl to the heated water reduced density differences between the heated and natural water. Determined flow velocities and dispersion changed according to the variation of the wetland shape. The introduced method allows to easily determining basic flow characteristics and when applied to other wetlands or shallow surface waters with complex structures, it may be the first step for a better process understanding.

2011

• Sucker, Carina, Wilpert, Klausvon, Puhlmann, Heike
  Acidification reversal in low mountain range streams of Germany
  2011 Environmental monitoring and assessment, Springer Netherlands, volume: 174, issue: 1-4, pages: 65 - 89
• Gudmundsson, Lukas, Tallaksen, Lena M., Stahl, Kerstin, Clark, Douglas B., Dumont, Egon, Hagemann, Stefan, Bertrand, Nathalie, Gerten, Dieter, Heinke, Jens, Hanasaki, Naota, Voss, Frank, Koirala, Sujan
  Comparing Large-Scale Hydrological Model Simulations to Observed Runoff Percentiles in Europe
  2011 Journal of Hydrometeorology, American Meteorological Society, volume: 13, issue: 2, pages: 604 - 620
• Staudinger, M., Stahl, K., Seibert, J., Clark, M.P., Tallaksen, L.M.
  Comparison of hydrological model structures based on recession and low flow simulations
  2011 Hydrology and Earth System Sciences, volume: 15, issue: 11, pages: 3447 - 3459
• Morgenstern, Y. , Puhlmann, H., von Wilpert, K.
  Erfassung und erste Analysen von räumlichen Mustern der Bodenfeuchte auf Waldstandorten
  2011 Waldökologie, Landschaftsforschung und Naturschutz, volume: 12, pages: 47 - 59
• Schelker, J., Burns, D. A., Weiler, M., Laudon, H.
  Hydrological mobilization of mercury and dissolved organic carbon in a snow-dominated, forested watershed: Conceptualization and modeling
  2011 Journal of Geophysical Research, volume: 116, page: G01002
• Szeftel, Pascal, Moore, R. D., Weiler, Markus
  Influence of distributed flow losses and gains on the estimation of transient storage parameters from stream tracer experiments
  2011 Journal of Hydrology, volume: 396, issue: 3-4, pages: 277 - 291
• Gudmundsson, L., Tallaksen, L. M., Stahl, K., Fleig, A. K.
  Low-frequency variability of European runoff
  2011 Hydrology and Earth System Sciences, volume: 15, pages: 2853 - 2869
• Lange, J., Schuetz, T., Gregoire, C., Elsässer, D., Schulz, R., Passeport, E., Tournebize, J.
  Multi-tracer experiments to characterise contaminant mitigation capacities for different types of artificial wetlands
  2011 International Journal of Environmental Analytical Chemistry, volume: 91, issue: 7-8, pages: 768 - 785
• Lange, Jens, Schuetz, Tobias, Gregoire, Caroline, Elsässer, David, Schulz, Ralf, Passeport, Elodie, Tournebize, Julien
  Multi-tracer experiments to characterise contaminant mitigation capacities for different types of artificial wetlands
  2011 International Journal of Environmental Analytical Chemistry, volume: 91, issue: 7-8, pages: 768 - 785
• Leibundgut, C.
  Nachhaltige Wassernutzung
  2011 Gas, Wasser, Abwasser, volume: 12, pages: 879 - 885
• Schuetz, Tobias, Weiler, Markus
  Quantification of localized groundwater inflow into streams using ground-based infrared thermography
  2011 Geophys. Res. Lett., volume: 38, issue: 3, page: L03401
  » show abstract« hide abstract
  Abstract

  Due to temperature differences of groundwater and streamwater, localized groundwater inflows into small streams can directly be detected with ground-based thermographic systems in summer or winter. Infrared radiation temperatures of surface water were used to determine mixing length and to calculate the relative fraction of groundwater inflow to downstream discharge. These fractions were comparable to groundwater inflow fractions derived from electrical conductivity, kinetic water temperatures and discharge measurements. This approach advances the immediate detection and quantification of localized groundwater inflow for hydrology, geology and ecology.
• Breña Naranjo, J. A., Weiler, M., Stahl, K.
  Sensitivity of a data-driven soil water balance model to estimate summer evapotranspiration along a forest chronosequence
  2011 Hydrology and Earth System Sciences, Copernicus Publications, volume: 15, issue: 11, pages: 3461 - 3473
• Tallaksen, L.M., Stahl, K., Wong, G.
  Space-time characteristics of large-scale droughts in Europe derived from streamflow observations and WATCH multi-model simulations
  2011 , volume: 48, page: 16
• Stahl, K., Tallaksen, L. M., Gudmundsson, L., Christensen, J. H.
  Streamflow data from small basins: a challenging test to high resolution regional climate modeling
  2011 Journal of Hydrometeorology, volume: 12, pages: 900 - 912
• Puhlmann, H., von Wilpert, K.
  Test und Entwicklung von Pedotransferfunktionen für Wasserretention und hydraulische Leitfähigkeit von Waldböden
  2011 Waldökologie, Landschaftsforschung und Naturschutz, volume: 12, pages: 61 - 71
• Breña Naranjo, J. A., Weiler, M., Stahl, K.
  The potential of observed soil moisture dynamics for predicting summer evapotranspiration in a successional chronosequence
  2011 Hydrology and Earth System Sciences Discussion, volume: 8, issue: 3, pages: 5301 - 5318
• Hoffmann, P., Königer, P., Kern, F.-J., Schulla, J., Leibundgut, Ch., Krahe, P., Speer, W.
  Tritiumbilanzierung und Speicherermittlung im Wesergebiet unter Verwendung des hydrologischen Modellsystems WaSiM-ETH im Vergleich mit früheren Arbeiten
  2011 Hydrologie und Wasserbewirtschaftung, volume: 55, issue: 1, pages: 16 - 29
• Hrachowitz, M., Weiler, M.
  Uncertainty of Precipitation Estimates Caused by Sparse Gauging Networks in a Small, Mountainous Watershed
  2011 Journal of Hydrologic Engineering, volume: 16, issue: 5, pages: 460 - 471
• Grodek, T., Lange, J., Lekach, J., Husary, S.
  Urban hydrology in mountainous middle eastern cities
  2011 Hydrology and Earth System Sciences, Copernicus Publications, volume: 15, issue: 3, pages: 953 - 966
• Stölzle, M., Stahl, K.
  Wassernutzung und Trockenheitsindikatoren in Baden-Württemberg
  2011 Standort - Zeitschrift für angewandte Geographie, volume: 35, issue: 3, pages: 94 - 101

2010

• Varhola, A.W, Wawerla, J., Weiler, M., Coops, N.C., Bewley, D., Alila, Y.
  A new low-cost, standalone sensor system for snow monitoring
  2010 Journal of Atmospheric and Oceanic Technology, volume: in press
• Andrés Varhola, Jens Wawerla, Markus Weiler, Nicholas C. Coops , Daniel Bewley, Younes Alila
  A new low-cost, standalone sensor system for snow monitoring
  2010 Journal of Atmospheric and Oceanic Technology, volume: in press
• Passeport, E., Tournebize, J., Jankowfsky, S., Prömse, B, Chaumont, C., Coquet, Y., Lange, J.
  Artificial wetland and forest buffer zone: hydraulic and tracer characterization
  2010 Vadose Zone Journal, volume: 9, pages: 73 - 84
  » show abstract« hide abstract
  Abstract

  As part of a European LIFE ArtWET project, two on-site buffer zones, an artificial wetland and a forest plot, are being evaluated for their capacity to mitigate pesticide pollution. As treatment efficiency is highly dependent on the systems' hydrology, the present work focuses on the watershed and both systems' hydrological functioning. The design strategy involved limited inlet flow rates to 70 L s–1: 99% of watershed outlet flow rates were lower than this limit. Approximately half of the flows of greatest concern passed through the artificial wetland, whereas the forest only received 2% of these flows. A tracer experiment was conducted under a low steady flow rate while little vegetation was present in the artificial wetland. A water dye tracer (sulforhodamine B, SB) and two molecules of contrasting properties, uranine (Ur, photodegrading) and isoproturon (mobile and only slightly sorptive, IPU) were injected. Dilution, sorption, and photodegradation were observed. The forest plot, which presented a high organic matter content, showed more sorption (IPU, SB) but lower photodecay (Ur) than did the artificial wetland. Total IPU losses in the forest buffer were high (79%). In the artificial wetland, 30% IPU losses were found, whereas a 66.5-h mean retention time was determined and good hydraulic efficiency (0.55) was calculated. Few dead zones and short-circuits were found, suggesting good hydrological functioning. Implementing buffer zones in subsurface pipe-drained watersheds actively participates in the reduction of pesticide transfer to natural water bodies.
• Sophie Bachmair, Markus Weiler, Gunnar Nützmann
  Benchmarking of Two Dual-Permeability Models under Different Land Use and Land Cover
  2010 Vadose Zone Journal, volume: 9, page: 226–237
• Bachmair, S., Weiler, M., Nützmann, G.
  Benchmarking the predictive capacity of two dual-permeability models for structured soil under different land use and land cover
  2010 Vadose Zone Journal, volume: 9, pages: 226 - 237
• Samuels, R., Rimmer, A., Hartmann, A., Krichak, S., Alpert, P.
  Climate Change Impacts on Jordan River Flow: Downscaling Application from a Regional Climate Model.
  2010 Journal of Hydrometeorology, volume: 11, issue: 4, page: 860–879
• C. Gascuel-Odoux, M. Weiler, J. Molenat
  Effect of the spatial distribution of physical aquifer properties on water table depth and stream discharge in a headwater catchment
  2010 Hydrology and Earth System Sciences, volume: 14, pages: 1179 - 1194
• Stoll, S., Weiler, M.
  Explicit simulations of stream networks to guide hydrological modelling in ungauged basins
  2010 Hydrology and Earth System Sciences, volume: 14, issue: 8, pages: 1435 - 1448
• Sebastian Stoll , Markus Weiler
  Explicit simulations of stream networks to guide hydrological modelling in ungauged basins
  2010 Hydrology and Earth System Sciences, volume: 14, issue: 8, pages: 1435 - 1448
• Varhola, A., Coops, N.C., Weiler, M., Moore, R.D.
  Forest canopy effects on snow accumulation and ablation: an integrative review of empirical results
  2010 Journal of Hydrology, volume: in press
• A. Varhola , N.C. Coops, M. Weiler , R.D. Moore
  Forest canopy effects on snow accumulation and ablation: an integrative review of empirical results
  2010 Journal of Hydrology, volume: in press
• McDonnell, J. J., McGuire, K., Aggarwal, P., Beven, K., Biondi, D., Destouni, G., Dunn, S., James, A., Kirchner, J., Kraft, P., Lyon, S., Maloszewski, P., Newman, B., Pfister, L., Rinaldo, A., Rodhe, A., Sayama, T., Seibert, J., Solomon, K., Soulsby, C., Stewart, M., Tetzlaff, D., Tobin, C., Troch, P., Weiler, M., Western, A., Wörman, A., Wrede, S.
  How old is the streamwater? Open questions in catchment transit time conceptualization, modelling and analysis
  2010 Hydrological Processes, volume: 24, issue: 12, pages: 1745 - 1754
• Arbel, Youval, Greenbaum, Noam, Lange, Jens, Inbar, Moshe
  Infiltration processes and flow rates in developed karst vadose zone using tracers in cave drips
  2010 Earth Surface Processes and Landforms, John Wiley & Sons, Ltd., volume: 35, issue: 14, pages: 1682 - 1693
  » show abstract« hide abstract
  Abstract

  The purpose of this research was to identify groundwater recharge mechanisms and measure flow velocities through the epikarst and the vadose zone in a typical site of Mediterranean carbonate karst in natural rain conditions. By avoiding artificial flushing more realistic travel times could be measured, and the effective resultant vadose flow velocity could be inferred. Additionally, detailed monitoring enabled better description and quantification of infiltration and percolation processes. Nine different cave drips were monitored and sampled for three hydrological years in fractured karst lithology on Mount Carmel, Israel. At three drips, discharge was measured continuously by tipping buckets. Rainfall and soil water content were recorded above the cave. An artificial tracer experiment was conducted using uranine placed in a joint and at the soil–rock interface at soil pockets, both 27 m above the cave. Four hydrological types of drips: post-storm, seasonal, perennial, and overflow, were identified; each demonstrating different characteristics in terms of discharge and chemistry. The maximum effective flow velocities (uranine dye arrival times) were 41–76 cm/h; tracer mass flux was computed from the uranine breakthrough curves and drip hydrographs. The dominant flow velocities, derived from the peak of tracer mass flux, were 0·35–0·41 cm/h from post-storm drips, and 22–24 cm/h from the other drips. ‘Pulse-through’ (intra-event piston flow) was indicated by the time lags between the increase in drip rate and the time of drop in salinity and appearance of the tracer in most of the measured drips. Chloride concentrations were used to distinguish between ‘old/matrix water’ and ‘preferential-flow water’ in the perennial drips, demonstrating a two-component mixing model. In 2005–2006 ‘preferential-flow water’ reached up to 20–25% from annual discharge of these drips. This study promoted a method to compute dominant effective flow rates in the vadose zone in natural rain conditions. Copyright © 2010 John Wiley & Sons, Ltd.
• Roa-García, M. C., M. Weiler
  Integrated response and transit time distributions of watersheds by combining hydrograph separation and long-term transit time modeling
  2010 Hydrology and Earth System Sciences, volume: 14, issue: 8, pages: 1537 - 1549
• Fleig, A.K., Tallaksen, L.M., Hisdal, H., Stahl, K., Hannah, D.M
  Inter-comparison of weather and circulation type classifications for hydrological drought
  2010 Physics and Chemistry of the Earth, volume: 35, pages: 507 - 515
• Leibundgut, Ch.
  Langfristige Sicherung der Schweizer Wasserressourcen: Zum Start eines Forschungsprogramms
  2010 Hydrologie und Wasserbewirtschaftung, volume: 54, issue: 3, pages: 203 - 208
• Hannah, D. M., Demuth, S., van Lanen, H. A. J., Looser, U., Prudhomme, C., Rees, G., Stahl, K., Tallaksen, L. M.
  Large-scale river flow archives: importance, current status and future needs. Invited commentary.
  2010 Hydrological Processes, John Wiley & Sons, Ltd., volume: 25, pages: 1191 - 1200
• Volkmann, Till H. M., Lyon, Steve W., Gupta, Hoshin V., Troch, Peter A.
  Multicriteria design of rain gauge networks for flash flood prediction in semiarid catchments with complex terrain
  2010 Water Resources Research, AGU, volume: 46, issue: 11, page: W11554
  » show abstract« hide abstract
  Abstract

  Despite the availability of weather radar data at high spatial (1 km2) and temporal (5&#8211;15 min) resolution, ground-based rain gauges continue to be necessary for accurate estimation of storm rainfall input to catchments during flash flood events, especially in mountainous catchments. Given economical considerations, a long-standing problem in catchment hydrology is to establish optimal placement of a small number of rain gauges to acquire data on both rainfall depth and spatiotemporal variability of intensity during extreme storm events. Using weather radar observations and a dense network of 40 tipping bucket rain gauges, this study examines whether it is possible to determine a reliable &#8220;best&#8221; set of rain gauge locations for the Sabino Canyon catchment near Tucson, Arizona, USA, given its complex topography and dominant storm track pattern. High-quality rainfall data are used to evaluate all possible configurations of a &#8220;practical&#8221; network having from one to four rain gauges. A multicriteria design strategy is used to guide rain gauge placement, by simultaneously minimizing the residual percent bias and maximizing the coefficient of correlation between the estimated and true mean areal rainfall and minimizing the normalized spatial mean squared error between the estimated and true spatiotemporal rainfall distribution. The performance of the optimized rain gauge network was then compared against randomly designed network ensembles by evaluating the quality of streamflows predicted using the Kinematic Runoff and Erosion (KINEROS2) event-based rainfall-runoff model. Our results indicate that the multicriteria strategy provided a robust design by which a sparse but accurate network of rain gauges could be implemented for semiarid basins such as the one studied.
• Leibundgut, Ch.
  Nachhaltige Sicherung von Wasserressourcen – das NFP 61 im Spiegel globaler und nationaler Herausforderungen
  2010 Wasser Energie Luft, volume: 102, issue: 3, pages: 222 - 228
• Anderson, A. E., Weiler, M., Hudson, R. O., Alila, Y.
  Piezometric response in zones of a watershed with lateral preferential flow as a first-order control on subsurface flow
  2010 Hydrological Processes, volume: 24, issue: 16, pages: 2237 - 2247
  » show abstract« hide abstract
  Abstract

  Characterizing zones of a watershed based on the water table is used to understand and predict internal watershed processes. In watersheds dominated by lateral preferential flow, the water table response typically shows a distinct hydraulically limited pattern. This response is characterized by a capping of the rising water table when the lateral preferential flow features are activated and subsurface flow still increases. We expected that this response would be related to the contributing area since nearby hillslope excavations showed that the development of preferential flow network was positively correlated with the contributing area. The watershed was stratified into three predetermined zones and installed 25 piezometers to measure the water table dynamics. The objectives were (1) to characterize the water table–runoff relationship, (2) to prove preferential flow by observable characteristics and (3) to test the feasibility of identifying areas within a watershed that are dominated by lateral preferential flow. Watershed zones were not well defined and there was no strong relationship between the hydraulically limited response and observable watershed characteristics. Although zones might still be useful for grouping the hillslope processes, the piezometric response may not be an appropriate indicator for mapping the watershed into areas with runoff dominated by lateral preferential flow.
• Shadeed, S., Lange, J.
  Rainwater harvesting to alleviate water scarcity in dry conditions: A case study in Faria Catchment, Palestine
  2010 Water Science and Engineering, volume: 3, issue: 2, pages: 132 - 143
  » show abstract« hide abstract
  Abstract

  In arid and semi-arid regions, the availability of adequate water of appropriate quality has become a limiting factor for development. This paper aims to evaluate the potential for rainwater harvesting in the arid to semi-arid Faria Catchment, in the West Bank, Palestine. Under current conditions, the supply-demand gap is increasing due to the increasing water demands of a growing population with hydrologically limited and uncertain supplies. By 2015, the gap is estimated to reach 4.5 × 106 m3. This study used the process-oriented and physically-based TRAIN-ZIN model to evaluate two different rainwater harvesting techniques during two rainfall events. The analysis shows that there is a theoretical potential for harvesting an additional 4 × 106 m3 of surface water over the entire catchment. Thus, it is essential to manage the potential available surface water supplies in the catchment to save water for dry periods when the supply-demand gap is comparatively high. Then a valuable contribution to bridging the supply-demand gap can be made.
• Heske, C. and Hötzl, H. and Neukum, H.
  Schadensdetektion an Abwasserkanälen mit Multisensorsystemen
  2010 Schriftenreihe angewandte Geologie Karlsruhe, volume: 82
• Gudmundsson, L., Tallaksen, L. M., Stahl, K.
  Spatial cross-correlation patterns of European low, mean and high flows
  2010 Hydrological Processes, volume: 25, page: 1034–1045
  » show abstract« hide abstract
  Abstract

  Abstract 10.1002/hyp.7807.abs Low and high flows are associated with different hydrological processes. High flows correspond to the direct response of catchments to water input, whereas low flows occur in pronged dry periods and are governed by depleting storages. Therefore, the inter-annual dynamics of high and low flows are often considered to be independent. To shed light on this assumption, we analysed a pan-European dataset of 615 streamflow records, summarized as time series of annual streamflow percentiles (5th, 10th, …, 95th). The analysis was based on comparing the spatial cross-correlation patterns derived from the different percentile series. Their interrelation was visualized by projecting them into a low-dimensional space. We found that large parts of the cross-correlations of the percentile series can be summarized by one dominating component. This component represents geographical continuous regions in Europe of correlated streamflow. Departures from this mean pattern occurred for low and high flows and were characterized by the corresponding spatial correlation functions. Generally, spatial correlations appear to be stronger for high flows than for mean flows, particularly for short distances (<400 km). Low flows, on the other hand, have the lowest spatial correlations for short distances. For longer distances (>800 km), this pattern reverses and the spatial correlation of low flows become largest. This discrepancy between low and high flows suggests that hydrological systems are more homogeneously linked to climatic fluctuations under wet conditions. Under dry conditions, local catchment properties appear to play a larger role in translating climatic fluctuations into hydrological response. Copyright © 2010 John Wiley & Sons, Ltd.
• Koeniger, Paul, Leibundgut, Christian, Link, Timothy, Marshall, John D.
  Stable isotopes applied as water tracers in column and field studies
  2010 Organic Geochemistry, volume: 41, pages: 31 - 40
• Hermann, Andreas and Schumann, Sybille
  Status and Perspectives of Hydrology in Small Basins
  2010 IAHS Publ. (Red Book Series), volume: 336
• Schumann, S. and Schmalz, B. and Meesenburg, H. and Schröder, U.
  Status ans Perspectives of Hydrology in small Basins
  2010 IHP-HWPR-Berichte, volume: 10
• Stahl, K., Hisdal, H., Hannaford, J., Tallaksen, L. M., van Lanen, H. A. J., Sauquet, E., Demuth, S., Fendekova, M., Jódar, J.
  Streamflow trends in Europe: evidence from a dataset of near-natural catchments
  2010 Hydrology and Earth System Sciences, volume: 14, pages: 2367 - 2382
  » show abstract« hide abstract
  Abstract

  Streamflow observations from near-natural catchments are of paramount importance for detection and attribution studies, evaluation of large-scale model simulations, and assessment of water management, adaptation and policy options. This study investigates streamflow trends in a newly-assembled, consolidated dataset of near-natural streamflow records from 441 small catchments in 15 countries across Europe. The period 1962–2004 provided the best spatial coverage, but analyses were also carried out for longer time periods (with fewer stations), starting in 1932, 1942 and 1952. Trends were calculated by the slopes of the Kendall-Theil robust line for standardized annual and monthly streamflow, as well as for summer low flow magnitude and timing. A regionally coherent picture of annual streamflow trends emerged, with negative trends in southern and eastern regions, and generally positive trends elsewhere. Trends in monthly streamflow for 1962–2004 elucidated potential causes for these changes, as well as for changes in hydrological regimes across Europe. Positive trends were found in the winter months in most catchments. A marked shift towards negative trends was observed in April, gradually spreading across Europe to reach a maximum extent in August. Low flows have decreased in most regions where the lowest mean monthly flow occurs in summer, but vary for catchments which have flow minima in winter and secondary low flows in summer. The study largely confirms findings from national and regional scale trend analyses, but clearly adds to these by confirming that these tendencies are part of coherent patterns of change, which cover a much larger region. The broad, continental-scale patterns of change are mostly congruent with the hydrological responses expected from future climatic changes, as projected by climate models. The patterns observed could hence provide a valuable benchmark for a number of different studies and model simulations.
• Varhola, A., Teti, P., Boon, S., Coops, N.C., Weiler, M., Bater, C.W.
  The influence of ground and LiDAR-derived forest structure metrics on snow accumulation and ablation in disturbed forests
  2010 Canadian Journal of Forest Research, volume: 40, issue: 4, pages: 812 - 821
• Lange, J., Arbel, Y., Grodek, T.,, Greenbaum, N.
  Water percolation process studies in a Mediterranean karst area
  2010 Hydrological Processes, volume: 24, issue: 13, pages: 1866 - 1879
  » show abstract« hide abstract
  Abstract

  To investigate processes of water percolation, the drip response of stalactites in a karstic cave below a 143 m2 sprinkling plot was measured. The experiment was conducted in Mount Carmel, Israel, at the end of the dry season and intended to simulate a series of two high-intensity storms on dry and wet soils. In addition to hydrometric measurements (soil moisture, surface runoff, stalactite dripping rates), two types of tracers (electrical conductivity and bromide) were used to study recharge processes, water origin and mixing inside a 28-m vadose zone. Results suggested that slow, continuous percolation through the rock matrix is of minor importance and that percolating water follows a complicated pattern including vertical and horizontal flow directions. While bromide tracing allowed identification of quick direct flow paths at all drips with maximum flow velocities of 4Ð3 m/h, mixing analysis suggested that major water fractions were mobilized by piston flow, pushing out water stored in the unsaturated zone above the cave. Under dry preconditions, 80 mm of artificial rainfall applied in less than 7 h was not enough to initiate significant downward water percolation. Most water was required to fill uppermost soil and rock storages. Under wet preconditions during the second day sprinkling, higher water contents in soils and karst cavities facilitated piston flow effects and a more intense response of the cave drips. Results indicate that in Mediterranean karst regions, filling of the unsaturated zone, including soil and rock storages, is an important precondition for the onset of significant water percolation and recharge. This results in a higher seasonal threshold for water percolation than for the generation of surface runoff.

2009

• Asadian, Y., Weiler, M.
  A New Approach in Measuring Rainfall Interception by Urban Trees in Coastal British Columbia
  2009 Water Quality Research Journal of Canada, volume: 44, issue: 1, pages: 16 - 25
• Yeganeh Asadian, Markus Weiler
  A New Approach in Measuring Rainfall Interception by Urban Trees in Coastal British Columbia
  2009 Water Quality Research Journal of Canada, volume: 44, issue: 1, pages: 16 - 25
• Lange, J., Gunkel, A.
  Abschlussbericht: GLOWA Jordan River Phase 2 - Teilvorhaben 5: Hydrologische Modellierung (blue water)
  2009
• Coops, N.C., Bater, C.W., Varhola, A., Teti, P., Boon, S., Weiler, M.
  Assessing Differences in Tree and Stand Structure Following Beetle Infestation using LiDAR Data
  2009 Canadian Journal of Remote Sensing, volume: 35, issue: 6, pages: 497 - 508
• Nicholas C. Coops, Christopher W. Bater , Andres Varhola , Pat Teti , Sarah Boon, Markus Weiler
  Assessing Differences in Tree and Stand Structure Following Beetle Infestation using LiDAR Data
  2009 Canadian Journal of Remote Sensing, volume: 35, issue: 6, pages: 497 - 508
• Bachmair, S., Weiler, M., Nützmann, G.
  Controls of land use and soil structure on water movement: Lessons for pollutant transfer through the unsaturated zone
  2009 Journal of Hydrology, volume: 369, issue: 3-4, pages: 241 - 252
• S. Bachmair, M. Weiler, G. Nützmann
  Controls of land use and soil structure on water movement: Lessons for pollutant transfer through the unsaturated zone
  2009 Journal of Hydrology, volume: 369, issue: 3-4, pages: 241 - 252
• Rupp, T., Ullrich, T., Westermann, E., Hämmerle, R. et. Al.
  Das Natur- und Landschaftschutzgebiet "Elzwiesen"
  2009 Naturschutz am südlichen Oberrein, volume: 5
• Déry, S. J., , K. Stahl, , R. D. Moore, , P. H. Whitfield, , B. Menounos, , J. E. Burford
  Detection of runoff timing changes in pluvial, nival, and glacial rivers of western Canada
  2009 Water Resources Research, volume: 45
• Markus Weiler, Cornelia Scheffler, Art Tautz, Klemens Rosin
  Development of a Hydrologic Process Model for Mountain Pine Beetle affected Areas in British Columbia
  2009 Institut für Hydrologie, page: 44
• Carver, Martin, Weiler, M., Stahl, K., Scheffler, Cornelia, Schneider, J., Brena Naranjo, A.J.
  Development of a low-flow hazard model for the Fraser basin, British Columbia
  2009 Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, page: 25
• Anderson, A. E., Weiler, M., Alila, Y., Hudson, R.O.
  Dye staining and excavation of a lateral preferential flow network
  2009 Hydrology and Earth System Sciences, volume: 13, pages: 935 - 944
  » show abstract« hide abstract
  Abstract

  Preferential flow paths have been found to be important for runoff generation, solute transport, and slope stability in many areas around the world. Although many studies have identified the particular characteristics of individual features and measured the runoff generation and solute transport within hillslopes, very few studies have determined how individual features are hydraulically connected at a hillslope scale. In this study, we used dye staining and excavation to determine the morphology and spatial pattern of a preferential flow network over a large scale (30 m). We explore the feasibility of extending small-scale dye staining techniques to the hillslope scale. We determine the lateral preferential flow paths that are active during the steady-state flow conditions and their interaction with the surrounding soil matrix. We also calculate the velocities of the flow through each cross-section of the hillslope and compare them to hillslope scale applied tracer measurements. Finally, we investigate the relationship between the contributing area and the characteristics of the preferential flow paths. The experiment revealed that larger contributing areas coincided with highly developed and hydraulically connected preferential flow paths that had flow with little interaction with the surrounding soil matrix. We found evidence of subsurface erosion and deposition of soil and organic material laterally and vertically within the soil. These results are important because they add to the understanding of the runoff generation, solute transport, and slope stability of preferential flow-dominated hillslopes.
• A. E. Anderson, M. Weiler, Y. Alila, R. O. Hudson
  Dye staining and excavation of a lateral preferential flow network
  2009 Hydrology and Earth System Sciences, volume: 13, pages: 935 - 944
  » show abstract« hide abstract
  Abstract

  Preferential flow paths have been found to be important for runoff generation, solute transport, and slope stability in many areas around the world. Although many studies have identified the particular characteristics of individual features and measured the runoff generation and solute transport within hillslopes, very few studies have determined how individual features are hydraulically connected at a hillslope scale. In this study, we used dye staining and excavation to determine the morphology and spatial pattern of a preferential flow network over a large scale (30 m). We explore the feasibility of extending small-scale dye staining techniques to the hillslope scale. We determine the lateral preferential flow paths that are active during the steady-state flow conditions and their interaction with the surrounding soil matrix. We also calculate the velocities of the flow through each cross-section of the hillslope and compare them to hillslope scale applied tracer measurements. Finally, we investigate the relationship between the contributing area and the characteristics of the preferential flow paths. The experiment revealed that larger contributing areas coincided with highly developed and hydraulically connected preferential flow paths that had flow with little interaction with the surrounding soil matrix. We found evidence of subsurface erosion and deposition of soil and organic material laterally and vertically within the soil. These results are important because they add to the understanding of the runoff generation, solute transport, and slope stability of preferential flow-dominated hillslopes.
• Morin, E. , Grodek, Tamir, Enzel, Yehouda, Dahan, Ofer, Benito, Gerardo, Külls, Christoph , Jacoby, C. , van Langenhove, G., Seely, Mary
  Flood routing and alluvial aquifer recharge along the ephemeral arid Kuiseb River, Namibia.
  2009 Journal of Hydrology, volume: 368, pages: 262 - 275.
• Moore, R. D., Fleming, S. W., Menounos, B., Wheate, R., Fountain, A., Stahl, K., Holm, K., Jakob, M.
  Glacier change in western North America: influences on hydrology, geomorphic hazards and water quality
  2009 Hydrological Processes, volume: 23, issue: 1, pages: 42 - 61
  » show abstract« hide abstract
  Abstract

  The glaciers of western Canada and the conterminous United States have dominantly retreated since the end of the Little Ice Age (LIA) in the nineteenth century, although average rates of retreat varied from strong in the first-half of the twentieth century, with glaciers stabilizing or even advancing until 1980, and then resuming consistent recession. This retreat has been accompanied by statistically detectable declines in late-summer streamflow from glacier-fed catchments over much of the Study area, although there is some geographical variation: over recent decades, glaciers in northwest BC and southwest Yukon have lost mass dominantly by thinning with relatively low rates of terminal retreat, and glacier-fed streams in that region have experienced increasing flows. In many valleys, glacier retreat has produced geomorphic hazards, including outburst floods from moraine-dammed lakes, mass failures from oversteepened valley walls and debris flows generated on moraines. In addition to these hydrologic and geomorphic changes, evidence is presented that glacier retreat will result in higher stream temperatures, possibly transient increases in suspended sediment fluxes and concentrations, and changes in water chemistry. With climate projected to continue warming over the twenty-first century, current trends in hydrology, geomorphology and water quality should continue, with a range of implications for water resources availability and management and hydroecology, particularly for cool and cold-water species such as salmonids. Copyright (C) 2008 John Wiley & Sons, Ltd.
• Adolph, G.
  Kombination von Isotopenmethoden und Grundwassermodellen in der Altlastenbearbeitung
  2009 Freiburger Schriften zur Hydrologie, volume: 28, page: 206 pp
• Benito, Gerardo, Rohde, Rick, Seely, Mary, Külls, Christoph, Dahan, Ofer, Enzel, Yehouda, Todd, Simon, Botero, Blanca, Morin, E., Grodek, T., Roberts, Carol
  Management of alluvial aquifers in two southern African ephemeral rivers: Implications for IWRM.
  2009 J. Water Res. Managm., volume: 24, issue: 4, pages: 641 - 667
• Shea, J. M., Moore, R. D., Stahl, K.
  Melt Factors for regional modeling of glacier Mass Balance
  2009 Journal of Glaciology, volume: 55, issue: 189, pages: 123 - 130
  » show abstract« hide abstract
  Abstract

  Melt factors for snow (ks ) and ice (ki ) were derived from specific mass-balance data and regionally interpolated daily air-temperature series at nine glaciers in the western Cordillera of Canada. Fitted ks and ki were relatively consistent across the region, with mean values (standard deviations) of 3.04 (0.38) and 4.59 (0.59) mm d−1 ◦ C−1 , respectively. The interannual variability of melt factors was investigated for two long-term datasets. Calculated annually, snow- and ice-melt factors were relatively stable from year to year; standard deviations for snowmelt factors were 0.48 (17%) and 0.42 (18%) at Peyto and Place Glaciers, respectively, while standard deviations of ice-melt factors were 1.17 (25%) and 0.81 (14%). While fitted values of ks are comparable to those presented in previous observational and modeling studies, fitted ki are substantially and consistently lower across the region. Fitted melt factors were sensitive to the choice of lapse rate used in the air-temperature interpolation. Melt factors fitted to mass-balance data from a single site (Place Glacier) provided reasonable summer balance predictions at most other sites representing both maritime and continental climates, although there was a tendency for under-prediction at several sites. The combination of regionally interpolated air temperatures and a degree-day model appears capable of generating first-order estimates of regional summer balance, which can provide a benchmark against which to judge the predictive ability of more complex (e.g. energy balance) models applied at a regional scale. Mass-balance sensitivity analyses indicate that a temperature increase of 1 K will increase summer ablation in the region by 0.51 m w.e. a−1 on average.
• Gregoire, C., Elsaesser, D, Huguenot, D., Lange, J., Lebeau, T., Merli, A., Mose, R., Passeport, E., Payraudeau, S., Schuetz, T., Schulz, R., Tapia-Padilla, G., Tournebize, J., Trevisan, M., Wanko, A.
  Mitigation of Agricultural Nonpoint-Source Pesticide Pollution in Artificial Wetland Ecosystems - A Review
  2009 Sustainable Agriculture Reviews, volume: Volume 2, pages: 293 - 338
• Koeniger, P., Leibundgut, Ch., Stichler, W.
  Spatial and temporal characterisation of stable isotopes in river water as indicators of groundwater contribution and confirmation of modelling results; a study of the Weser river, Germany
  2009 Isotopes in Environmental and Health Studies, volume: 45, issue: 4, pages: 289 - 302
• A. E. Anderson, M. Weiler, Y. Alila, R. O. Hudson
  Subsurface flow velocities in a hillslope with lateral preferential flow
  2009 Water Resources Research, volume: 45
• Michael Stölzle, Markus Weiler
  Untersuchung der Sedimentdynamik im Mündungsbereich der Argen
  2009 Institut für Hydrologie, page: 44
• Jost, George, Moore, R.D., Weiler, Markus, Gluns, David R., Alila, Younes
  Use of distributed snow measurements to test and improve a snowmelt model for predicting the effect of clear-cutting
  2009 Journal of Hydrology, volume: 376, issue: (1-2, pages: 94 - 106
• Georg Jost, R. D. Moore, Markus Weiler, David R. Gluns, Younes Alila
  Use of distributed snow measurements to test and improve a snowmelt model for predicting the effect of clear-cutting
  2009 Journal of Hydrology, volume: 376, issue: 1-2, pages: 94 - 106
  » show abstract« hide abstract
  Abstract

  Modeling the effect of forest clear-cutting with a distributed hydrological model can be used to detect hydrologic changes as an alternative to paired-catchment studies, and also to estimate the hydrologic sensitivity of a catchment to assist in forest management decisions. To model the effect of clear-cutting in a snow dominated forested watershed, a model needs to be able to simulate effects of all of the main controls on snow accumulation and melt. However, most studies that used a distributed modeling approach relied on one or a few sites for model testing. In this study, we employ a stratified nested sample layout that was specifically designed to test distributed models, involving measurement of snow water equivalent (SWE) under forest and in clearcuts over a range of elevations and aspects. To test the ability of a model to simulate the main controls on the spatial distribution of SWE, spatial gradients of observed and simulated SWE in relation to topographic and vegetation controls are computed using regression analysis. Comparison of observed and simulated gradients helps to highlight model weaknesses. The approach is applied to evaluate the snow algorithms in the distributed hydrology soil and vegetation model (DHSVM) using data collected in Cotton Creek, a snow dominated forested watershed in south-eastern British Columbia. SWE measurements were made from 2005 to 2008, covering peak snow accumulation and snow melt. Albedo decay and canopy transmittance were found to be the two processes that DSHVM version 3.0 did not simulate well enough to predict basin average differences between forests and clearcuts properly. After replacing the internal albedo decay functions with functions obtained from snow albedo measurements and changing the canopy transmittance function in the model, DHSVM was able to reproduce the major spatial patterns derived from snow surveys. Model performance is better during winter up to the peak snow accumulation than during snow melt. Spatial patterns of peak snow accumulation in the snow-rich year 2006 can be modeled better than those after the warm winter of 2005. The influence of aspect on snow accumulation and snowmelt is underestimated by DHSVM. While we have focused specifically on DHSVM, the methods developed in this study should be generally useful for model testing purposes and important in the context of interpretation of modeling results, in particular when dealing with large spatial datasets.
• Trubilowicz, J., Cai, K., Weiler, M.
  Viability of motes for hydrological measurement
  2009 Water Resources Research, volume: 45
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  Abstract

  Low-cost, low-power wireless sensor networks (mote networks) have the potential to revolutionize data collection methods in hydrology. They promise the ability to monitor catchments at very high spatial and temporal resolution with flexible sampling schemes, real time data processing and high levels of quality control. We operated an experimental network of 41 motes monitoring seven different parameters each at 15 min intervals for 10 months in a small forested catchment in southwestern British Columbia, Canada, to determine if this emerging technology is suitable for use by hydrologists in its current form. Our particular interests were ease of setup, sampling reliability, power consumption, and hardware resilience. We found that while motes gave the ability to monitor a catchment at resolution levels that were previously impossible, they still need to evolve into an easier to use, more reliable platform before they can replace traditional data collection methods.

2008

• Schwientek, M.
  Biogeochemical characterization of the groundwater system at the Test Field Scheyern using environmental isotopes
  2008 Freiburger Schriften zur Hydrologie, volume: 27, page: 105 pp
• Dunn, S. M., Freer, J., Weiler, M., Kirkby, M. J., Seibert, J., Quinn, P. F., Lischeid, G., Tetzlaff, D., Soulsby, C.
  Conceptualization in catchment modelling: simply learning?
  2008 Hydrological Processes, volume: 22, issue: 13, pages: 2389 - 2393
• Stahl, K., Moore, R. D., Shea, J. M., Hutchinson, D., Cannon, A. J.
  Coupled modelling of glacier and streamflow response to future climate scenarios
  2008 Water Resources Research, volume: 44, issue: 2, page: -
  » show abstract« hide abstract
  Abstract

  This study investigated the sensitivity of streamflow to changes in climate and glacier cover for the Bridge River basin, British Columbia, using a semi-distributed conceptual hydrological model coupled with a glacier response model. Mass balance data were used to constrain model parameters. Climate scenarios included a continuation of the current climate and two transient GCM scenarios with greenhouse gas forcing. Modelled glacier mass balance was used to re-scale the glacier every decade using a volume-area scaling relation. Glacier area and summer streamflow declined strongly even under the steady-climate scenario, with the glacier retreating to a new equilibrium within 100 years. For the warming scenarios, glacier retreat continued with no evidence of reaching a new equilibrium. Uncertainty in parameters governing glacier melt produced uncertainty in future glacier retreat and streamflow response. Where mass balance information is not available to assist with calibration, model-generated future scenarios will be subject to significant uncertainty.
• Klaus, Julian, Külls, Christoph, Dahan, Ofer
  Evaluating the recharge mechanism of the Lower Kuiseb Dune area using mixing cell modeling and residence time data
  2008 Journal of Hydrology, volume: 358, issue: 3-4, pages: 304 - 316
  » show abstract« hide abstract
  Abstract

  Summary A mixing cell approach was extended by a method incorporating mean cell residence times derived from 14C to further constrain and validate the modeling results. This extended approach was used to model the groundwater system of the Lower Kuiseb Dune area in Namibia. The Kuiseb river is a 560 km long ephemeral river that crosses the Namib Desert from east to west. Transmission losses from the riverbed during flood events are an important source of groundwater recharge to the underlying aquifer system. The Lower Kuiseb area is located in a hyper arid region with annual precipitation less than 25 mm/yr. Hydrochemical data from 13 wells in the area were used in the mixing cell model (MCM). End members were identified as sources for the groundwater found in the Lower Kuiseb, including inflow from the crystalline basement plateau north of the Kuiseb as well as floodwater from the Kuiseb river. A conceptual groundwater recharge and flow model was developed, and then inverse mixing cell modeling was carried out using hydrochemical tracers. This approach generally allows for several possible solutions. After completing the inverse modeling, a forward mixing cell model was developed by varying the mean residence time of each cell to fit calculated 14C data to the measured 14C data. This new approach joins previously developed methods solely based on conservative mixing or residence time optimization. Based on the results of the model the fraction of floodwater in different sections of the Lower Kuiseb groundwater systems was calculated, ranging from 61% to 98.2%. In addition to floodwater, groundwater inflow from the crystalline basement north of the Kuiseb was shown to contribute to the Lower Kuiseb aquifer, accounting for salinization during periods without flooding.
• Grégoire, C., Lange, J.
  Exploitation (et limites) de la notion de symétrie pour la quantification du transfert de pesticides dans les vignobles badois et alsaciens
  2008 Revue Géographique de L'est, volume: XLVII, issue: 2/2007, pages: 79 - 90
• Tromp-van Meerveld, I., Weiler, M.
  Hillslope dynamics modeled with increasing complexity
  2008 Journal of Hydrology, volume: 361, issue: 1-2, pages: 24 - 40
  » show abstract« hide abstract
  Abstract

  Few studies have investigated how much model complexity is needed to simulate both the hillslope outflow and the internal hillslope dynamics. We studied the influence of model complexity on simulations for the Panola Mountain trenched hillslope. We analyzed the influences of the inclusion of bedrock permeability, variable soil depth and preferential flow on modeled hillslope responses. We found that without the inclusion of bedrock leakage the long-term subsurface flow response measured at the trenchface and the threshold relation between total precipitation and total subsurface flow could not be simulated adequately. Individual events could stilt be represented acceptably, showing the importance of long time series for model calibration and validation. The use of spatially constant bedrock conductivity allowed us to simulate spatially variable bedrock leakage rates because of the spatially variable depths of saturation. Without variable soil depth the spatial variability of subsurface flow along the trenchface and its temporal dynamics during events could not be represented. In addition the spatial patterns of saturation at the soil-bedrock interface did not agree with the observed patterns and responses to smaller events were underestimated. Inclusion of preferential flow mainly influenced the distribution of the maximum saturation depths at the soil-bedrock interface and increased peak flows and recessions. Soil moisture measurements were less useful for model validation for the Panola hillslope than measurements of the spatial patterns of saturation and subsurface flow. We plea for a new blue print for the set-up of hillslope experiments such that their data is useful for studies on hillslope model complexity and for model validation and rejection. (C) 2008 Elsevier B.V. All rights reserved.
• Wenninger, Jochen, Uhlenbrook, Stefan, Lorentz, Simon, Leibundgut, Christian
  Identification of runoff generation processes using combined hydrometric, tracer and geophysical methods in headwater catchment in South Africa
  2008 Hydrological Sciences Journal, volume: 53, issue: 1, pages: 65 - 80
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  Abstract

  Classical hydrometric measurements and detailed 2-D electrical resistivity imaging (ERI) surveys were combined with tracer sampling to identify the hydrological processes in a semi-arid headwater catchment in the Eastern Cape Province of South Africa. The analysis of precipitation and runoff events emphasized the strong link between precipitation and runoff formation characteristics. Soil water tension and groundwater level observations demonstrated the development of a perched water table within the soil layer. These results are supported by tracer-based runoff component separations and illustrate the important role of the shallow subsurface component. The ERI investigation permitted further insight into the structure of the subsurface. Finally, the ERI survey, in combination with time domain reflectometry (TDR) measurements, allowed the extrapolation of selective soil water content measurements. To summarize, the application and combination of different field methods led to the development of a conceptual model of the hydrological functioning of this catchment. The dominant role of the subsurface mechanisms was evaluated.
• Dahan, Ofer, Tatarsky, B., Enzel, Yehouda, Külls, Christoph, Seely, Mary, Benito, Gerardo
  Insight into the dynamic process of flood water infiltration - Kuiseb River, Namibia.
  2008 Ground Water, volume: 46, issue: 3, pages: 450 - 461
• Floyd, W., Weiler, M.
  Measuring snow accumulation and ablation dynamics during rain-on-snow events: innovative measurement techniques
  2008 Hydrological Processes, volume: 22, issue: 24, pages: 4805 - 4812
  » show abstract« hide abstract
  Abstract

  Rain-on-snow (ROS) is the primary generator of peak flow events in mountainous coastal regions of North America. Uncertainty remains as to the role of forest canopy interception leading up to and during ROS events. Much of this uncertainty can be attributed to a lack of suitable techniques to collect data during ROS, due in part to the dynamic nature of climatic conditions, particularly related to snow accumulation and melt. We supplemented a meteorological network with non-weighing snow melt lysimeters, suspended spring scales to measure snow throughfall and an automated time lapse photography network to monitor state of precipitation (rain vs. snow), snow accumulation/ablation, canopy interception and unloading of snow from the canopy. Image analysis software allowed for the extraction of data from images. Rapid loading and unloading of snow from the canopy, closely linked to changes in temperature, was observed using this approach. We were also able to continuously monitor throughfall snow water equivalent using low cost suspended spring scales. This experimental design allowed us to capture information previously unavailable without direct observation. Copyright (C) 2008 John Wiley & Sons, Ltd.
• Aukema, B. H., Carroll, A. L., Zheng, Y., Zhu, J., Raffa, K. F., Moore, R. D., Stahl, K., Taylor, S. W.
  Movement of outbreak populations of mountain pine beetle: influences of spatiotemporal patterns and climate
  2008 Ecography, volume: 31, issue: 3, pages: 348 - 358
  » show abstract« hide abstract
  Abstract

  Insect outbreaks exert landscape-level influences, yet quantifying the relative contributions of various exogenous and endogenous factors that contribute to their pattern and spread remains elusive. We examine an outbreak of mountain pine beetle covering an 800 thousand ha area on the Chilcotin Plateau of British Columbia, Canada, during the 1970s and early 1980s. We present a model that incorporates the spatial and temporal arrangements of outbreaking insect populations, as well as various climatic factors that influence insect development. Onsets of eruptions of mountain pine beetle demonstrated landscape-level synchrony. On average, the presence of outbreaking populations was highly correlated with outbreaking populations within the nearest 18 km the same year and local populations within 6 km in the previous two years. After incorporating these spatial and temporal dependencies, we found that increasing temperatures contributed to explaining outbreak probabilities during this 15 yr outbreak. During collapse years, landscape-level synchrony declined while local synchrony values remained high, suggesting that in some areas host depletion was contributing to population decline. Model forecasts of outbreak propensity one year in advance at a 12 by 12 km scale provided 80% accuracy over the landscape, and never underestimated the occurrence of locally outbreaking populations. This model provides a flexible approach for linking temperature and insect population dynamics to spatial spread, and complements existing decision support tools for resource managers.
• Stumpp, Christine
  Quantification of heterogeneity in the unsaturated flow using environmental isotopes
  2008 Freiburger Schriften zur Hydrologie, Institute of Hydrology, volume: 26, page: 112 pp
• Uhlenbrook, Stefan, Didszun,Jens, Wenninger, Jochen
  Source areas and mixing of runoff components at the hillslope scale - a multi-technical approach
  2008 Hydrological Sciences Journal, volume: 53, issue: 4, pages: 741 - 753
  » show abstract« hide abstract
  Abstract

  Hillslope processes (i.e. water flow pathways, source areas and residence times) are essential for predicting water quantities and water quality. A multi-technical approach using classical hydrometry, natural and artificial tracers and electrical resistivity tomography (ERT) was applied to two adjacent steep hillslopes in the Black Forest Mountains, Germany. The differences in the hydrological and hydrochemical responses during three floods were larger than expected based on previously available information of topography, land use and geology. At one site a very dynamic shallow groundwater system dominated the flood generation, which could not be observed at the other site. The reasons for the heterogeneity of hillslope processes are the different soils and structures of the periglacial drift (first-order control); this is augmented by the different land use (pasture vs forest) and its effects on the near-surface processes (second-order control). The multi-technical approach proved very useful: the tracer methods enabled the detection and quantification of runoff components; geophysical methods provided further insights into the subsurface structure and, consequently, the origin of runoff components.
• Burn, D. H., Buttle, J. M., Caissie, D., MacCulloch, G., Spence, C., Stahl, K.
  The Processes, Patterns and Impacts of Low Flows Across Canada
  2008 Canadian Water Resources Journal, volume: 33, issue: 2, pages: 107 - 123
  » show abstract« hide abstract
  Abstract

  This paper provides an overview of low flow characteristics for six regions of Canada: the Arctic; the Mountains; the Prairies; southern Ontario; the Canadian Shield and the Atlantic. Processes that influence low flows arc contrasted between the six regions examined. Data from a common analysis period for 51 gauging stations arc used to evaluate flow duration curves and to explore the relationship between low flows and drainage area. The results reveal a diversity of processes influencing low flows and Illustrate important regional differences in low flow characteristics and the impacts associated with low flows.
• Kuras, P. K., Weiler, M., Alila, Y.
  The spatiotemporal variability of runoff generation and groundwater dynamics in a snow-dominated catchment
  2008 Journal of Hydrology, volume: 352, issue: 1-2, pages: 50 - 66
  » show abstract« hide abstract
  Abstract

  The intricacies of hydrometeorological process interactions with basin physiography in snow-dominated catchments may only be acknowledged through the recognition and study of the spatiotemporal heterogeneity of runoff generation and groundwater dynamics. Subsurface flow mechanisms have a direct influence on stream runoff generation. In order to better understand the coupling of these processes, the linkages between stream runoff generation and groundwater dynamics need to also be considered. This study collectively examines the spatiotemporal variability of stream runoff generation and groundwater dynamics in a snow-dominated catchment in south-central British Columbia by monitoring basin outlet flow, continuous groundwater fluctuations at 9 locations, and instantaneous flows at 42 locations throughout the stream network. Observed groundwater levels were found to be more responsive to inputs in the upper hillslopes with flow accumulation in the lower slopes, and strong groundwater level correlations with stream runoff generally decreased with increasing distances from streams. The specific discharge of reach contributing areas was found to be significantly correlated to various physiographical parameters including contributing area, an index of average hillslope flow velocity, reach length, elevation, and slope. Nested subcatchment stream runoff scaled positively in a power law relation with contributing area (r(2) = 0.74-0.88), and sub-basin discharge was found to scale near linearly with drainage areas ranging 0.9 ha-4.74 km(2). The findings of this study are in general agreement with the concept of the transmissivity feedback mechanism; lateral inflows to streams contributed relatively new water during periods of greater runoff contribution, whereas during the low-flow summer period, hillslopes in a hydrologically dry state produced waters that experienced longer mean residence times. In order to better understand the coupling of subsurface flow mechanisms and stream runoff generation, it is suggested that future work should emphasize spatially-intensive continuous measurements of stream network flows in combination with comprehensive groundwater level monitoring. (c) 2007 Elsevier B.V. All rights reserved.
• Königer, P., Schwientek, M., Uhlenbrook, S., Leibundgut, Ch., Krause, W.J.
  Tritium balance in macro-scale river basins analysed through distributed hydrological modelling
  2008 Hydrological Processes, volume: 22, issue: 5, pages: 567 - 576
  » show abstract« hide abstract
  Abstract

  The recession of bomb tritium in river discharge of large basins indicates a contribution of slowly moving water. For an appropriate interpretation it is necessary to consider different runoff components (e.g. direct runoff and ground water components) and varying residence times of tritium in these components. The spatially distributed catchment model (tracer aided catchment model, distributed; TACD) and a tritium balance model (TRIBIL) were combined to model process-based tritium balances in a large German river basin (Weser 46 240 km2) and seven embedded sub-basins. The hydrological model (monthly time step, 2 × 2 km2) estimated the three major runoff components: direct runoff, fast-moving and slow-moving ground water for the period of 1950 to 1999. The model incorporated topography, land use, geomorphology, geology and hydro-meteorological data. The results for the different basins indicated a contribution of direct runoff of 30-50% and varying amounts for fast and slow ground water components. Combining these results with the TRIBIL model allowed us to estimate the residence time of the components. Mean residence times of 8 to 14 years were found for the fast ground water component, 21 to 93 years for the slow ground water component and 14 to 50 years for an overall mean residence time within these basins. Balance calculations for the Weser basin indicate an over-estimation of loss of tritium through evapotranspiration (more than 60%) and decay (10%). About 28% were carried in stream-flow where direct runoff contributed about 12% and ground water runoff 13% in relation to precipitation input over the studied 50-year period. Neighbouring basins and nuclear power plants contributed about 1% each over this time period. Copyright © 2007 John Wiley & Sons, Ltd.

2007

• Leibundgut, Ch.
  Abflussbildung und Einzugsgebietmodellierung
  2007 Freiburger Schriften zur Hydrologie, Institute of Hydrology, volume: 24, page: 203 pp
• Renaud, JP , Cloke, HL, Weiler, M
  An assessment of the tracer-based approach to quantifying groundwater contributions to streamflow - Comment
  2007 Water Resources Research, volume: 43, issue: 9
• Brandes, Elke, Wenninger, Jochen, Koeniger, Paul, Schindler, Dirk, Rennenberg, Heinz, Leibundgut, Christian, Mayer, Helmut, Gessler, Arthur
  Assessing environmental and physiological controls over water relations in a Scots pine (<i>Pinus sylvestris</i> L.) stand through analyses of stable isotope composition of water and organic matter
  2007 Plant, Cell and Environment, volume: 30, issue: 1, pages: 113 - 127
  » show abstract« hide abstract
  Abstract

  This study investigated the influence of meteorological, pedospheric and physiological factors on the water relations of Scots pine, as characterized by the origin of water taken up, by xylem transport as well as by carbon isotope discrimination (039413C) and oxygen isotope enrichment (039418O) of newly assimilated organic matter. For more than 1 year, we quantified 03B42H and 03B418O of potential water sources and xylem water as well as 039413C and 039418O in twig and trunk phloem organic matter biweekly, and related these values to continuously measured or modelled meteorological parameters, soil water content, stand transpiration (ST) and canopy stomatal conductance (Gs). During the growing season, 03B418O and 03B42H of xylem water were generally in a range comparable to soil water from a depth of 2201320 cm. Long residence time of water in the tracheids uncoupled the isotopic signals of xylem and soil water in winter. 039418O but not 039413C in phloem organic matter was directly indicative of recent environmental conditions during the whole year. 039418O could be described applying a model that included 18O fractionation associated with water exchange between leaf and atmosphere, and with the production of organic matter as well as the influence of transpiration. Phloem 039413C was assumed to be concertedly influenced by Gs and photosynthetically active radiation (PAR) (as a proxy for photosynthetic capacity). We conclude that isotope signatures can be used as effective tools (1) to characterize the seasonal dynamics in source and xylem water, and (2) to assess environmental effects on transpiration and Gs of Scots pine, thus helping to understand and predict potential impacts of climate change on trees and forest ecosystems.
• Zagana, E., Obeidat, M., Kuells, Ch., Udluft, P.
  Chloride, hydrochemical and isotope methods of groundwater recharge estimation in eastern Mediterranean areas: a case study in Jordan
  2007 Hydrological Processes, volume: 21, issue: 16, pages: 2112 - 2123
  » show abstract« hide abstract
  Abstract

  Jordan is classified as an arid to semi-arid country with a population according to 1999 estimates of 4·8 millions inhabitants and a growth rate of 3·4%. Efficient use of Jordan's scarce water is becoming increasingly important as the urban population grows. This study was carried out within the framework of the joint European Research project lsquoGroundwater recharge in the eastern Mediterraneanrsquo and describes a combined methodology for groundwater recharge estimation in Jordan, the chloride method, as well as isotopic and hydrochemical approaches. Recharge estimations using the chloride method range from 14 mm year-1 (mean annual precipitation of 500 mm) for a shallow and stony soil to values of 3·7 mm year-1 for a thick desert soil (mean annual precipitation of 100 mm) and values of well below 1 mm year-1 for thick alluvial deposits (mean annual rainfall of 250 mm). Isotopically, most of the groundwater in the Hammad basin, east Jordan, falls below the global meteoric water line and far away from the Mediterranean meteoric water line, suggesting that the waters are ancient and were recharged in a climate different than Mediterranean. Tritium levels in the groundwater of the Hammad basin are less than the detection limit (<1*3 TU). However, three samples in east Hammad, where the aquifer is unconfined, present tritium values between 1 and 4 TU. Copyright © 2007 John Wiley & Sons, Ltd.
• Khanchoul, Kamel, Jansson, Margareta B., Lange, Jens
  Comparison of suspended sediment yield in two catchments, northeast Algeria
  2007 Zeitschrift für Geomorphologie, volume: 51, issue: 1, pages: 63 - 94 (32)
  » show abstract« hide abstract
  Abstract

  The present work compares the suspended sediment yields in the two catchments Saf Saf (322 km2) and Kebir West (1,130 km2). The suspended sediment transport of sampled storms were calculated using additional concentrations from a regression of the storm in question. For storms with no or few water samples, a sediment rating curve was used, developed with the discharge class method. The mean annual sediment yield during flood events of the 22 years of the study period was 461 T km−2 in the Saf Saf drainage basin and 247 T km−2 in the Kebir West basin. Although the Saf Saf drainage basin had lower rainfall and runoff, the erosion was higher. The high sediment yield in the Saf Saf basin could be explained by a high percentage of agricultural land, and cultivation developed on shallow marly silty-clayey soils with steep slopes often exceeding 23%, while in the Kebir West catchment there is a smaller percentage of cultivated areas which are found on less steep slopes with deeper soils. The negative impacts of this enhanced sediment mobility are directly felt in the Zardézas reservoir which collects the flows of the Saf Saf catchment. In storms of high magnitude during the winter and spring seasons, wadi Saf Saf had greatly peaked graphs of water discharge and sediment concentration which implies surface runoff with high erosion because cultivated areas are often furrowed downslope during the winter season, while wadi Kebir West had broad graphs of discharge and comparatively low concentrations.
• Weiler, M., McDonnell, J.J.
  Conceptualizing lateral preferential flow and flow networks and simulating the effects on gauged and ungauged hillslopes
  2007 Water Resources Research, volume: 43
• Stahl, K.
  Hydrology of the World's International River basins: hydrological parameters for use in global studies of international water-relations
  2007 Gobal Runoff Data Centre, page: 52
• McGuire, K., Weiler, M., McDonnell, J.
  Integrating tracer experiments with modeling to assess runoff processes and water transit times
  2007 Advances in Water Resources, volume: 30, page: 824–837
• Zagana, E., Kuells, Ch. , Udluft, P., Constantinou, C.
  Methods of groundwater recharge estimation in eastern Mediterranean - a water balance model application in Greece, Cyprus and Jordan
  2007 Hydrological Processes, volume: 21, issue: 18, pages: 2405 - 2414
  » show abstract« hide abstract
  Abstract

  Groundwater recharge studies in semi-arid areas are fundamental because groundwater is often the only water resource of importance. This paper describes the water balance method of groundwater recharge estimation in three different hydro-climatic environments in eastern Mediterranean, in northwest Greece (Aliakmonas basin/Koromilia basin), in Cyprus (Kouris basin and Larnaka area) and in Jordan (northern part of Jordan). For the Aliakmonas basin, groundwater recharge was calculated for different sub-catchments. For the Upper Aliakmonas basin (Koromilia basin), a watershed-distributed model was developed and recharge maps were generated on a daily basis. The mean annual recharge varied between 50 and 75 mm/year (mean annual rainfall 800 mm/year). In Cyprus, the mean groundwater recharge estimates yielded 70 mm/year in the Kouris basin. In the Larnaka area, groundwater recharge ranged from 30 mm/year (lowland) to 200 mm/year (mountains). In Jordan, the results indicated recharge rates ranging from 80 mm/year for very permeable karstified surfaces in the upper part of the Salt basin, where rainfall reaches 500 mm/year to less than 10 mm/year and to only about 1 mm/year in the southernmost part of the basin. For the north part of Jordan, a watershed-distributed model was developed and recharge maps were generated. This water balance model was used for groundwater recharge estimations in many regions with different climatic conditions and has provided reliable results. It has turned out to be an important tool for the management of the limited natural water resources, which require a detailed understanding of regional hydro(geo)logical processes. Copyright © 2007 John Wiley & Sons, Ltd.
• Koch, A.
  Modellierung der hydrodynamischen Wechselwirkungen einer Flusslandschaft
  2007 Freiburger Schriften zur Hydrologie, Institute of Hydrology, volume: 23, page: 199 pp
• McDonnell, J.J., Sivapalan, M., Vache, K., Dunn, S., Grant, G., Haggerty, R., Hinz, C., Hooper, R., Kirchner, J., Roderick, M. L., Selker, J., Weiler, M.
  Moving beyond heterogeneity and process complexity: A new vision for watershed hydrology
  2007 Water Resources Research, volume: 43, issue: 7
  » show abstract« hide abstract
  Abstract

  Field studies in watershed hydrology continue to characterize and catalogue the enormous heterogeneity and complexity of rainfall runoff processes in more and more watersheds, in different hydroclimatic regimes, and at different scales. Nevertheless, the ability to generalize these findings to ungauged regions remains out of reach. In spite of their apparent physical basis and complexity, the current generation of detailed models is process weak. Their representations of the internal states and process dynamics are still at odds with many experimental findings. In order to make continued progress in watershed hydrology and to bring greater coherence to the science, we need to move beyond the status quo of having to explicitly characterize or prescribe landscape heterogeneity in our (highly calibrated) models and in this way reproduce process complexity and instead explore the set of organizing principles that might underlie the heterogeneity and complexity. This commentary addresses a number of related new avenues for research in watershed science, including the use of comparative analysis, classification, optimality principles, and network theory, all with the intent of defining, understanding, and predicting watershed function and enunciating important watershed functional traits.
• Wenninger, Jochen
  Prozesshydrologische Untersuchung im System Boden - Vegetation - Atmosphäre
  2007 Freiburger Schriften zur Hydrologie, Institute of Hydrology, volume: 25, page: 151 pp
• Stumpp,Christine, Maloszewski, Piotr, Stichler, Willibald, Maciejewski, Stanislaw
  Quantification of the heterogeneity of the unsaturated zone based on environmental deuterium observed in lysimeter experiments
  2007 Hydrological Sciences Journal, volume: 52, issue: 4, pages: 748 - 762
  » show abstract« hide abstract
  Abstract

  An approach is presented which enables the quantification, in integrative form, of the preferential flow and the heterogeneity in water transport through the unsaturated zone under natural atmospheric conditions. For these purposes, deuterium transport was estimated in seven lysimeters filled with different sediment materials by applying a conceptual model, which consists of preferential and matrix flow paths for each using the lumped parameter approach. The piston flow and dispersion transit time distribution functions were assumed, for preferential and matrix flow paths, respectively. Weekly 2H data measured in precipitation (1984–1991) were taken as the input function. Combining modelling of isotopes and hydrological data enabled the quantification of preferential flow rates. The fraction of preferential flow directly appearing in the outflow within one week varied between 17 and 30%. The fraction of preferential flow was practically independent of the soil texture and flow rates. The crucial parameter influencing the fraction of direct flow was found to be the saturated hydraulic conductivity (Ks). In the matrix flow, it was found that the apparent dispersion parameter (PD)* is indirectly proportional to the mean water content (Theta). This relationship shows that the heterogeneity of the water flux in the matrix is higher for lower water contents. Finally, the transit time distribution functions, determined for both flow paths and the fractions of preferential flow, were used to construct vulnerability diagrams. Such a diagram gives the amounts of tracer mass (conservative pollutant), which appear weekly in the outflow between 0 and 60 weeks. The vulnerability diagrams showed different patterns for different soils, depending on the saturated conductivity and mean water content. Coarser material with low Theta and high Ks showed a short mean transit time for the matrix flow (about 10 weeks) and mean preferential flow equal to or higher than 20%. Finer sand, with lower Ks and higher Theta, resulted in mean transit times of approximately 30 weeks and preferential flow of 17–21%. These diagrams can be used to estimate the vulnerability of groundwater to pollution for different soil materials of the unsaturated zone.
• Burns, Douglas A., Klaus, Julian, McHale, Michael R.
  Recent climate trends and implications for water resources in the Catskill Mountain region, New York, USA
  2007 Journal of Hydrology, volume: 336, issue: 1-2, pages: 155 - 170
  » show abstract« hide abstract
  Abstract

  Summary Climate scientists have concluded that the earth's surface air temperature warmed by 0.6 °C during the 20th century, and that warming induced by increasing concentrations of greenhouse gases is likely to continue in the 21st century, accompanied by changes in the hydrologic cycle. Climate change has important implications in the Catskill region of southeastern New York State, because the region is a source of water supply for New York City. We used the non-parametric Mann-Kendall test to evaluate annual, monthly, and multi-month trends in air temperature, precipitation amount, stream runoff, and potential evapotranspiration (PET) in the region during 1952-2005 based on data from 9 temperature sites, 12 precipitation sites, and 8 stream gages. A general pattern of warming temperatures and increased precipitation, runoff, and PET is evident in the region. Regional annual mean air temperature increased significantly by 0.6 °C per 50 years during the period; the greatest increases and largest number of significant upward trends were in daily minimum air temperature. Daily maximum air temperature showed the greatest increase during February through April, whereas minimum air temperature showed the greatest increase during May through September. Regional mean precipitation increased significantly by 136 mm per 50 years, nearly double that of the regional mean increase in runoff, which was not significant. Regional mean PET increased significantly by 19 mm per 50 years, about one-seventh that of the increase in precipitation amount, and broadly consistent with increased runoff during 1952-2005, despite the lack of significance in the mean regional runoff trend. Peak snowmelt as approximated by the winter-spring center of volume of stream runoff generally shifted from early April at the beginning of the record to late March at the end of the record, consistent with a decreasing trend in April runoff and an increasing trend in maximum March air temperature. This change indicates an increased supply of water to reservoirs earlier in the year. Additionally, the supply of water to reservoirs at the beginning of winter is greater as indicated by the timing of the greatest increases in precipitation and runoff--both occurred during summer and fall. The future balance between changes in air temperature and changes in the timing and amount of precipitation in the region will have important implications for the available water supply in the region.
• Johnson, M. S., Weiler, M., Couto, E. G., Riha, S. J., Lehmann, J.
  Storm pulses of dissolved CO2 in a forested headwater Amazonian stream explored using hydrograph separation
  2007 Water Resources Research, volume: 43, issue: 11, page: -
  » show abstract« hide abstract
  Abstract

  Dissolved CO2 dynamics in stormflow and event water versus preevent water contributions to storm hydrographs were assessed in a forested headwater catchment of the Brazilian Amazon using high-frequency data. We applied the transfer function hydrograph separation model (TRANSEP) using specific conductance as a conservative tracer, finding preevent water to average 0.79 +/- 0.03 of storm discharge (mean +/- 1 SE for n = 14 storms). In situ, direct measurements of dissolved CO2 were able to capture new hydrobiogeochemical processes in real time, including CO2 pulses observed on the falling limb of storm hydrographs, the magnitudes of which were inversely related to preevent water fractions (r = -0.97, p < 0.0001).
• Wagener, T , Weiler, M , McGlynn, B , Gooseff, M , Meixner, T , Marshall, L , McGuire, K , McHale, M
  Taking the pulse of hydrology education
  2007 Hydrological Processes, volume: 21, issue: 13, pages: 1789 - 1792
• Jost, G., Weiler, M., Gluns, D. R., Alila, Y.
  The influence of forest and topography on snow accumulation and melt at the watershed-scale
  2007 Journal of Hydrology, volume: 347, issue: 1-2, pages: 101 - 115
  » show abstract« hide abstract
  Abstract

  Snow accumulation and melt are the two most important processes contributing to the spring freshet, the main hydrological event in snow-dominated watersheds. The magnitude and timing of the spring freshet is determined by the spatial variability of melt rates and peak snow water equivalent (SWE). Although it is known that the spatial variability of SWE is controlled by topography and vegetation, their combined influence on snow accumulation and melt at the watershed-scale has only been addressed in a few studies. The high small-scale variability of a snowpack combined with the classical sampling technique along transects makes it difficult to estimate how much of the observed spatial variability in SWE can be attributed to topographic and vegetative controls such as elevation, aspect, wind, and forest type, and how much of it is local variability. A nested stratified sampling design was developed for the snow courses in this study, where small-scale variability at the plot-scale was integrated by 12 snow density and 60 snow depth measurements, while the variability at the watershed-scale was captured by 19 strata, defined by elevation, aspect, and forest cover (either clearcut or forest). Snow course sampling was carried out during the spring of 2005, a year with 25% below average snow accumulation, and in spring of 2006, a year with 25% above average snow accumulation for the region. Snow accumulation in both years and snowmelt for a period in the spring of 2006 are analysed with multiple linear regressions and spatial autocorrelation of SWE with variogram analysis. The combination of elevation, aspect, and forest cover explained about 80-90% of the large-scale variability in snow accumulation for both years. At the plot-scale the coefficient of variation was higher under the forest canopy than in clearcuts, but did not relate to topographic controls. Elevation had the greatest influence on SWE in both years, with a steeper gradient in the snow rich year, whereas aspect had a similar effect in both years. In the mild winter of 2005, forests accumulated 39% less snow than clearcuts, while in 2006, forests had 27% less snow than clearcuts. Relative to the mean, aspect had a greater influence on snow accumulation than forest cover in the mild winter of 2005. Elevation played the most important role in snowmelt, while both aspect and forest cover had a comparable effect with slightly less influence than elevation. Almost all variograms show a clear sill, confirming that in the majority of cases, a 60 x 60 m plot size was adequate in capturing the variability of the plot-scale. In general, the degree of spatial autocorrelations is persistent in the snowmelt season for both years. This study has shown that it is possible to separate large-scale variability created by topography and forest cover from plot-scale variability through specifically designed snow surveys. The methods and data set of this study are useful in testing spatially-distributed snowmelt models and in developing new algorithms that reflect the relationships between the factors controlling the spatial variability of SWE. (c) 2007 Elsevier B.V. All rights reserved.

2006

• Fischer, A., Bauer, J., Meckenstock, R. U., Stichler, W., Griebler, C., Maloszewski, P., Kästner, M., Richnow, H.H.
  A mulitracer test proving the reliability of Rayleigh equation - Based approach for assessing biodegradation in a BTEX contaminated aquifer
  2006 Environmental Sciences & Technologies, volume: 40, pages: 4245 - 5252
• Stahl, K., Moore, R. D., McKendry, I. G.
  Climatology of winter cold spells in relation to mountain pine beetle mortality in British Columbia, Canada
  2006 Climate Research, volume: 32, issue: 1, pages: 13 - 23
  » show abstract« hide abstract
  Abstract

  A recent epidemic of mountain pine beetles (MPB) has caused mortality in extensive stands of pine trees in British Columbia, Canada. The epidemic has been attributed, in part, to the recent warming trend in winter in western Canada, as MPB experience mortality during extreme cold spells. This study aimed to clarify the roles of synoptic-scale circulation and large-scale climate modes in these recent trends. Potential cold-mortality events were identified by comparing recorded daily minimum air temperatures with experimentally determined critical thresholds. Annual event frequency has declined over past decades, and between 1998 and 2001 temperatures did not reach the 100% MPB mortality thresholds at the stations analysed. Event frequencies depended on the phase of the teleconnection indices. In particular, after the shift to a predominantly positive phase of the Pacific Decadal Oscillation (PDO) following 1976, cold-mortality events occurred mainly during strongly negative Arctic Oscillation (AO) years. The dominant synoptic-scale circulation pattern causing widespread low temperatures is Arctic Outbreak, although other circulation types can be important, depending on location. The frequencies of these cold circulation types varied with the teleconnection indices. In addition, the conditional probability of temperatures cold enough to cause MPB mortality for a given synoptic type varies with the teleconnection phase, particularly for the Pacific North America circulation pattern and PDO.
• Han, L. F., Maloszewski, P.
  Comment on 'LUMPED: a Visual Basic code of lumped-parameter models for mean residence time analyses of groundwater systems by Ozyurt and Bayari, Computers & Geosciences 29 (2003) 79-90'
  2006 Computers & Geosciences, volume: 32, issue: 5, pages: 708 - 712
• Stahl, K., Moore, R. D., Floyer, J. A., Asplin, M. G., McKendry, I. G.
  Comparison of approaches for spatial interpolation of daily air temperature in a large region with complex topography and highly variable station density
  2006 Agricultural and Forest Meteorology, volume: 139, issue: 3-4, pages: 224 - 236
  » show abstract« hide abstract
  Abstract

  This study compared 12 variations of regression-based and weighted-average approaches for interpolating daily maximum and minimum temperatures over British Columbia, Canada, a domain with complex topography and highly variable density and elevational distribution of climate stations. The approaches include simple extrapolation with elevation from the nearest climate station; nine variations of weighted-average methods employing three approaches to calculate lapse rates, two methods for station selection and three approaches for weight calculation; multiple linear regression using station coordinates as predictor variables; a method combining multiple regression and weighted averaging. Cross-validation for years with different densities and elevational distribution of climate stations showed varied mean prediction errors, which also depended on elevation and month. Methods that compute local lapse. rates from the control points performed better for years for which there were a greater number of higher-elevation stations, which allowed for better estimation of lapse rates. The methods that involved specified lapse rates all performed similarly, indicating that the method for selecting control stations and for calculating weights have less effect on predictive accuracy than the method for accounting for elevation. (c) 2006 Elsevier B.V. All rights reserved.
• Servat, E., Demuth, S.
  FRIEND - a global perspective 2002-2006
  2006 German IHP/HWRP National Committee, page: 202 pp
• Maloszewski, P., Wachniew, P., Czuprynski, P.
  Hydraulic characteristics of a wastewater treatment pond evaluated through tracer test and multi-flow mathematical approach
  2006 Polish Journal of Environmental Studies, volume: 15, issue: 1, pages: 105 - 110
• Eisele, Michael
  Hydrologische Güte - ein Beitrag zur erweiterten Bewertung von Flusseinzugsgebieten im Gewässerschutz
  2006 Freiburger Schriften zur Hydrologie, Institute of Hydrology, volume: 21, page: 90 pp
• Tilch, N., Uhlenbrook, S., Didszun, J., Wenninger, J., Kirnbauer, R., Zilgens, B., Leibundgut, Ch.
  Hydrologische Prozessforschung zur Hochwasserentstehung im Löhnersbach-Einzugsgebiet (Kitzbüheler Alpen, Österreich)
  2006 Hydrologie und Wasserbewirtschaftung, volume: 50, issue: H.2, pages: 67 - 78
  » show abstract« hide abstract
  Abstract

  Das Abflussgeschehen des Löhnersbaches (bei Saalbach, Kitzbüheler Alpen) variiert je nach Gebietszustand und Niederschlagscharakteristik erheblich. Mit Hilfe geophysikalischer und tracerhydrologischer Methoden konnten in einem mikroskaligen Teileinzugsgebiet mehrere, für diesen zentral alpinen Landschaftraum charakteristische Abflusskomponenten identifiziert sowie Informationen zu deren Herkunftsräumen, zeitlich variablen Dynamik und Abfluss-Beiträgen erzielt werden. Derartige Ergebnisse bieten die Grundlage für verbesserte prozessorientierte Niederschlag-Abfluss-Modellierungen.
• Stahl, K., Moore, R. D.
  Influence of watershed glacier coverage on summer streamflow in British Columbia, Canada
  2006 Water Resources Research, volume: 42, issue: 6, page: -
  » show abstract« hide abstract
  Abstract

  [ 1] This study examined the effects of glacier cover on summer streamflow across British Columbia, Canada, by applying nonparametric tests to assess trends in August discharge. Field-significant negative streamflow trends were found for glacierized catchments but not for those lacking glaciers. Effects of interannual climatic variations were accounted for by regressing August streamflow against August temperature and precipitation and July streamflow ( to account for carryover storage). Trend analyses of the regression residuals suggested first-order stationarity for unglacierized basins, but revealed widespread negative trends for glacier-fed rivers, particularly from 1976 to 1996, consistent with the effects of glacier retreat.
• Maduabuchi, C., Faye, S., Maloszewski, P.
  Isotope evidence of paleorecharge and palaeoclimate in the deep confined aquifers of the Chad Basin, NE Nigeria
  2006 Science of the Total Environment, volume: 370, pages: 467 - 479
  » show abstract« hide abstract
  Abstract

  Groundwaters from the Quaternary and Continental Terminal Formations in the Nigeria sector of the Chad Sedimentary Basin (CSB) together with rain and surface waters have been chemically and isotopically analyzed in order to investigate sources and ages of waters, possible modern renewal and mixing of the deep groundwaters, and to infer palaeoclimate incidences. Most of the waters are slightly to moderately mineralized and are of Na-HCO3 type induced mainly by Na-feldspar weathering and ion exchange reactions. The wide range of the δ18O and δ2H values and 3H contents in the upper aquifer indicate replenishment with modern meteoric water. However, the deep system (middle and lower aquifers) with a narrow range of depleted stable isotope values and low 14C activities indicates that these waters have a palaeometeoric origin. The period of infiltration was within the humid and cooler period (35 to 40 ka BP) prior to the Last Glacial Maximum. In addition, the isotope compositions of the deep system show no mixing with modern waters. These results are in agreement with other palaeorecord studies in the Sahel zone during this period.
• Maciejewski, Stanisław, Małoszewski, Piotr, Stumpp, Christine, Stichler, Willibald, Trimborn, Peter, Klotz, Dietmar
  Modelling of water flow through typical Bavarian soils: 1. Estimation of hydraulic characteristics of the unsaturated zone
  2006 Hydrological Sciences Journal, volume: 51, issue: 2, pages: 285 - 297
  » show abstract« hide abstract
  Abstract

  Over an eight-year period (1984–1991), seven experimental lysimeters filled with different soil materials from the State of Bavaria (quartz and tertiary sands, quartz and fluvioglacial gravels) were used to study water flow and tracer transport through the unsaturated zone under natural atmospheric conditions. The experiments were performed in the input–output mode using weekly water flow and tracer contents (environmental deuterium) in the precipitation and in the outflow in order to estimate the unsaturated hydraulic and transport parameters of the soils with limited measured data. This paper (Part 1) presents the evaluation of soil hydraulic parameters for tested soils, while the second paper (Part 2) is concerned with the estimation of transport parameters (dispersion, water content and possible zones with stagnant water). The estimation of the soil physical characteristics, i.e. the relationship between water pressure head and water content, performed by applying the van Genuchten model, showed a satisfactory accuracy against the measured data. Determination of the hydraulic conductivity as a function of water content using the van Genuchten-Mualem conductivity model did not yield good results, due to the fact that the theoretical water flow model based on such soil parameters was not able to fit the measured values of water content at the upper 20 cm and the cumulative water outflow simultaneously. To estimate the conductivity–water content characteristics, the inverse modelling technique was used for each lysimeter. The cumulative outflow curves were fitted to the observed outflow data by a trial-and-error procedure using the conductivity–water content relationship as the fitting function. It was shown that this method of estimating the soil characteristics yields parameters which are closer to the true values compared to those found in small-scale column experiments. The soil characteristics obtained in this part of the study were further used for modelling environmental deuterium transport through the soils (Part 2).
• Małoszewski, Piotr, Maciejewski, Stanisław, Stumpp, Christine, Stichler, Willibald, Trimborn, Peter , Klotz, Dietmar
  Modelling of water flow through typical Bavarian soils: 2. Environmental deuterium transport
  2006 Hydrological Sciences Journal, volume: 51, issue: 2, pages: 298 - 313
  » show abstract« hide abstract
  Abstract

  Seven experimental lysimeters were filled with different soil materials and used to study water flow and tracer transport through the unsaturated zone under natural atmospheric conditions during an eight year period (1984–1991). The study of soil characteristics and water flow was presented in Part 1. The present paper focuses on environmental deuterium transport. The concentrations of environmental deuterium were measured in both precipitation and the water outflowing from the lysimeters. Two model approaches were used to describe tracer transport. The numerical solution of water flow and two-phase mass transport equations, referred to here as the variable flow dispersion model (VFDM), can exactly simulate spatial and temporal distribution of flow and transport parameters. The fitting parameters of VFDM are the soil characteristics, the longitudinal dispersivity, the fraction of immobile water and the transfer constant between mobile and immobile water. However, the application of the VFDM for detailed transport simulations requires an adequate database, which is typically not available. That was the reason to introduce a second model, the lumped-parameter steady-state dispersion model (DM). This model assumes dispersive distribution of the transit time of a tracer particle between input and output from the system, has two fitting parameters: the apparent dispersion constant and the mean transit time of the tracer, and requires only input and output concentrations of tracer as a function of time. Both models were calibrated to the experimental data with similar accuracy. Using the VFDM it was possible to fit output concentrations with the same accuracy assuming that the entire volume of water takes part in motion. The results obtained with the DM demonstrated that this simple steady-state approach can be applied successfully to describe tracer transport under variable flow conditions. Both models have shown that, under applied experimental conditions, it is practically impossible to discover the existence of immobile water in the system.
• Maloszewski, Piotr, Wachniew, Przemyslaw, Czuprynski, Piotr
  Study of hydraulic parameters in heterogeneous gravel beds: Constructed wetland in Nowa Slupia (Poland)
  2006 Journal of Hydrology, volume: 331, issue: 3-4, pages: 630 - 642
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  Abstract

  Summary Combined use of tracers and mathematical modelling for evaluation of hydraulic characteristics of constructed wetlands is presented for the subsurface-flow system with Phragmites australis in Nowa Slupia (Poland). Instantaneously injected bromide and tritium tracers were used to obtain residence time distributions of wastewaters in three parallel inhomogeneous gravel cells of the wetland. The multi flow dispersion model, which assumes the existence of several flow-paths with different hydraulic properties was developed using the respective parallel combination of analytical solutions of the one-dimensional advection-dispersion equation. The model was used successfully to fit the experimental tracer breakthrough curves. Different flow components were identified and wastewater volumes, water-saturated porosity, mean wastewater travel times, longitudinal dispersivities as well as hydraulic conductivity of wetland cells were derived from model parameters. The variation in flow components and apparent hydraulic characteristics among wetland cells relate to the improper design and maintenance of the wetland. The single fissure dispersion model, which assumes possible diffusion of tracers into the zones with stagnant water during convective-dispersive flow through the mobile zone is adopted to the research conditions and used to model the TBC-s for one cell. The results show that this model can be calibrated with the satisfactory accuracy in that cell but yields unacceptable values of some parameters.
• Stahl, K., Moore, R. D., McKendry, I. G.
  The role of synoptic-scale circulation in the linkage between large-scale ocean-atmosphere indices and winter surface climate in British Columbia, Canada
  2006 International Journal of Climatology, volume: 26, issue: 4, pages: 541 - 560
  » show abstract« hide abstract
  Abstract

  In much of North America, variables such as temperature, precipitation, snowpack and streamflow are modulated by modes of large-scale ocean-atmosphere variability such as the Pacific Decadal Oscillation (PDO), El Nino-Southern Oscillation (ENSO) and the Pacific North American Pattern (PNA). In this study, we test the hypothesis that the influence of these modes on air temperature and precipitation in British Columbia (BC), Canada, can be explained in relation to changes in frequencies of synoptic-scale circulation types. A catalogue of 13 circulation types was derived by classifying daily mean sea-level pressure (MSLP) grids from 1948 to 2003. The grids cover BC and the North Pacific and were subjected to a standard pattern recognition algorithm employing principal component analysis followed by cluster analysis on the component scores. The circulation types are generally associated with distinctive patterns of precipitation and air temperature anomalies across BC. Multiple linear regressions for selected stations in BC using the type frequencies as predictors explain up to 75% of the variance of mean winter temperature and 65% of winter precipitation. The frequencies of most circulation types vary significantly between the different phases of ENSO, PDO and PNA in a manner consistent with the temperature anomalies associated with those modes and, to a lesser extent, with the more complex precipitation anomalies. In addition, however, average temperatures and precipitation amounts for some circulation types differ systematically between phases of ENSO and PDO. Subsequent analysis revealed distinct differences among ENSO and PDO phases in the upper-level circulation patterns associated with some surface types. A major part of the teleconnections can be explained through variations in the frequencies of synoptic-scale circulation types, but systematic within-type variability, particularly with PDO and PNA, can additionally influence the surface climate. Copyright (C) 2005 Royal Meteorological Society.
• Ludwig, K., Bremicker, M.
  The water balance model LARSIM - design, content and applications
  2006 Freiburger Schriften zur Hydrologie, Institute of Hydrology, volume: 22, page: 130 pp
• Konz, M., Uhlenbrook, S., Braun, L., Shresta, A., Demuth, S.
  Tradeoffs for the implementation of a process-based catchment model in a poorly gauged, highly glacierized Himalayan headwater
  2006 Hydrology and Earth System Sciences Discussion, volume: 3, issue: 6, pages: 3474 - 3515
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  Abstract

  The paper presents a catchment modeling approach for remote glacierized Himalayan catchments. The distributed catchment model TACD, which is widely based on the HBV model, was further developed for the application in highly glacierized catchments on a daily timestep and applied to the Nepalese Himalayan headwater Langtang Khola (360 km2). Low laying reference stations are taken for temperature extrapolation applying a second order polynomial function. Probability based statistical methods enable bridging data gaps in daily precipitation time series and the redistribution of cumulated precipitation sums over the previous days. Snow and ice melt was calculated in a distributed way based on the temperature-index method employing calculated daily potential sunshine durations. Different melting conditions of snow and ice and melting of ice under debris layers were considered. The spatial delineation of hydrological response units was achieved by taking topographic and physiographic information from maps and satellite images into account, and enabled to incorporate process knowledge into the model. Simulation results demonstrated that the model is able to simulate daily discharge for a period of 10 years and point glacier mass balances observed in the research area with an adequate reliability. The simple but robust data pre-processing and modeling approach enables the determination of the components of the water balance of a remote, data scarce catchment with a minimum of input data.
• McKendry, I. G., Stahl, K., Moore, R. D.
  Validation of surface synoptic types generated by a general circulation model: implications for downscaling
  2006 International Journal of Climatology, volume: 26, pages: 1727 - 1736
• Leibundgut, Ch., Kern, F.-J.
  Wasser in Deutschland - Mangel oder Überfluss?
  2006 Geographische Rundschau, volume: 58, pages: 12 - 18

Books

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2016

• UTB basics
  Hydrologie
  ISBN: 978-3-8252-4513-9
  Fohrer, N., Bormann, H., Miegel, K., Casper, M., Bronstert, A., Schumann, A., Weiler, M.
• Merkur Druck AG
  Traditionelle Bewässerung - ein Kulturerbe Europas - Band 1: Grundlagen
  ISBN: 978-3-905817-74-4
  Leibundgut, C., Vonderstrass, I.
• Merkur Druck AG
  Traditionelle Bewässerung - ein Kulturerbe Europas - Band 2: Regionale Dokumentation
  ISBN: 978-3-905817-75-1
  Leibundgut, C., Vonderstrass, I.

2009

• Wiley-Blackwell, page: 415
  Tracers in Hydrology
  ISBN: 978-0-470-51885-4
  Leibundgut, C., Maloszewski, P., Külls C.

Book chapters

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2019

• Henrichs, M., Steinbrich, A., Leistert, H., Scherer, I., Schuetz, T., Uhl, M., Weiler, M.
  Model Based Estimation of a Natural Water Balance as Reference for Planning in Urban Areas
  In: New Trends in Urban Drainage Modelling
  2019, Springer International Publishing, pages: 953 - 957, ISBN: 978-3-319-99867-1

2017

• Leibundgut, C.
  Die Bedeutung des Wassers für den Schwarzwald Wasser gestaltet den Natur- und Lebensraum früher und heute
  In: Der Schwarzwald
  2017, Der Schwarzwald, volume: E 6264, Heft 4,

2016

• Gangi, L., Hannah, D.M., Weiler, M.
  Microthermal variability in a Welsh upland stream
  In: River Science: Research and Management for the 21st Century
  2016, Wiley-Blackwell, pages: 279 - 294, ISBN: 978-1-119-99434-3

2015

• Hartmann, A., Mudarra, M., Marín, A., Andreo, B., Wagener, T.
  Relating Land Surface Information and Model Parameters for a Karst System in Southern Spain.
  In: Hydrogeological and Environmental Investigations in Karst Systems
  2015, Springer Berlin Heidelberg, volume: 1, page: 345–352),
• Leibundgut, Ch.
  Wasserressourcen am Oberrhein in Geschichte, Gegenwart und Zukunft
  In: Alemannisches Jahrbuch
  2015, Alemannisches Jahrbuch, Alemannisches Institut, volume: 61/62, Alemannisches Institut,

2013

• Leibundgut, C., Kohn, I.
  Traditionelle Bewässerung in Europa mit besonderer Berücksichtigung Deutschlands
  In: Die Queichniederung – Porträt einer Landschaft, Fauna und Flora in Rheinland-Pfalz
  2013, Gesellschaft für Naturschutz und Ornithologie Rheinland-Pfalz e.V. (GNOR), volume: 45, pages: 107 - 143,

2012

• Leibundgut, C.
  50 Jahre Umweltschutz und wie weiter?
  In: Jahrbuch des Oberaargaus
  2012, Verlag Merkur Langenthal, volume: 55, pages: 217 - 230,
• Leibundgut, C.
  50 Jahre Umweltschutz – und wie weiter?
  In: Jahrbuch des Oberaargaus
  2012, Merkur Druck, pages: 217 - 230,
• Steinbrich, A., Weiler, M.
  Abflussbildung und Abflusskomponenten
  In: Wasser- und Bodenatlas Baden-Württemberg
  2012, Umweltministerium Baden-Württemberg, volume: Atlastafel 6.5,
• Pinkswar, I., Kundzewicz, Z.W., Peduzzi, P., Brakenridge, G.R., Stahl, K., Hannaford, J.
  Changing floods in Europe
  In: Changes in flood risk in Europe
  2012, IAHS Press, issue: 10, pages: 83 - 96, ISBN: 1907161287
• Steinbrich, A., Weiler, M.
  Direktabflusshöhe: Hundertjährliches Niederschlagsereignis
  In: Wasser- und Bodenatlas Baden-Württemberg
  2012, Umweltministerium Baden-Württemberg, volume: Atlastafel 6.7,
• Steinbrich, A., Weiler, M.
  Einzugsgebietsbezogene Abflussbildung
  In: Wasser- und Bodenatlas Baden-Württemberg
  2012, Umweltministerium Baden-Württemberg, volume: Atlastafel 6.6,
• Kern, F.-J., Ritter M., Steinbrich A.
  Großwetterlagen und Hochwasser
  In: Wasser- und Bodenatlas Baden-Württemberg
  2012, Umweltministerium Baden-Württemberg, volume: Atlastafel 3.11,
• Kern, F.-J., Ritter M., Steinbrich A.
  Großwetterlagen und Niedrigwasser
  In: Wasser- und Bodenatlas Baden-Württemberg
  2012, Umweltministerium Baden-Württemberg, volume: Atlastafel 3.12,
• Hartmann, A., Rimmer, A., Lange, J., Wagener, T., Weiler, M.
  Identifizierung und Evaluierung von Karstmodellen mittels systembeschreibender Zielfunktionen
  In: Wasser ohne Grenzen - Beiträge zum Tag der Hydrologie am 22./23. März an der Albert-Ludwigs-Universität Freiburg
  2012, , page: 97–103,
• Rimmer, A., Hartmann, A.
  Simplified conceptual structures and analytical solutions for groundwater discharge using reservoir equations.
  In: Water Resources Management and Modeling
  2012, InTech, page: 217–338,
• Kändler, G., Riemer U., Kern; F.-J., Steinbrich A.
  Tatsächliche Baumartenzusammensetzung
  In: Wasser- und Bodenatlas Baden-Württemberg
  2012, Umweltministerium Baden-Württemberg, volume: Atlastafel 1.6,

2011

• Leibundgut, C.
  Die Wässermatten des Oberaargaus. Ein regionales Kulturerbe als Modell für Europa?
  In: Jahrbuch Oberaargau 2011
  2011, , pages: 121 - 144,
• Weiler, M.
  Field-Based Observation of Hydrological Processes
  In: Treatise on Water Science
  2011, Academic Press, page: 339–350,
• Leistert, H., Weiler, M.
  Hochaufgelöste Modellierung der Beschattung von Fließgewässern durch Vegetation und Topographie mittels LiDAR Daten
  In: Forum für Hydrologie und Wasserbewirtschaftung
  2011, Forum für Hydrologie und Wasserbewirtschaftung, volume: 30.11, ISBN: 978-3-941897-79-3
• Leistert, H., Weiler, M.
  Hochaufgelöste Modellierung der Beschattung von Fließgewässern durch Vegetation und Topographie mittels LiDAR Daten
  In: Hydrologie und Wasserbewirtschaftung - von der Theorie zur Praxis. Beiträge zum Tag der Hydrologie 2011. Forum für Hydrologie und Wasserbewirtschaftung 30.11
  2011, , pages: 193 - 199,
• Leibundgut, Ch., Kohn, I.
  L'irrigation traditionelle dans le contexte européen. Evolution - diffusion - fonctions - avenir
  In: Annales Valaisannes 2010-2011
  2011, SHVR, pages: 155 - 195,
• Leibundgut, Ch., Seibert, J.
  Tracer Hydrology
  In: Treatise on Water Science
  2011, Academic Press, volume: 2, page: 215–236 ,

2010

• Steinbrich, Andreas, Weiler, Markus
  Ausweisung der für die Hochwasserentstehung wichtigen Abflussbildungsprozesse für Baden-Württemberg
  In: Forum für Hydrologie und Wasserbewirtschaftung
  2010, Hydrologische Wissenschaften; Fachgemeinschaft in der DWA, Caspar, Markus; Gronz, Oliver, pages: 171 - 185, Caspar, Markus; Gronz, Oliver, ISBN: 978-3-941897-22-9
• Hartmann, A., Kralik, M., Humer, F., Lange, J., Weiler, M., LaMoreaux, J. W.
  Hydrological Modeling of an Alpine Dolomite Karst System
  2010, Springer Berlin Heidelberg, page: 223–229,
• Bachmair, S., Weiler, M.
  New dimensions of hillslope hydrology
  In: Forest Hydrology and Biogeochemistry: Synthesis of Research and Future Directions
  2010, Springer, page: in press,
• Sophie Bachmair, Markus Weiler
  New dimensions of hillslope hydrology
  In: Forest Hydrology and Biogeochemistry: Synthesis of Research and Future Directions
  2010, Springer, page: in press,
• Weiler, M., Pike, R., Spittlehouse, D., Winkler, R., Carlyle-Moses, D. , Jost, G. , Hutchinson, D., Hamilton, S., Marquis, P., Quilty, E., Moore, R.D., Richardson, J., Jordan, P., Hogan, D., Teti, P., Coops, N.
  Watershed Measurement Methods and Data Limitations
  In: Compendium of Forest Hydrology and Geomorphology in British Columbia
  2010, Min. For. Range, For. Sci. Prog., Victoria, B.C. and FORREX Forum for Research and Extension in Natural Resources, issue: 66,
• Moore, R.D., Spittlehouse, D., Whitfield, P.H., Stahl, K.
  Weather and Climate
  In: Compendium of forest hydrology and geomorphology in British Columbia
  2010, Min. For. Range, For. Sci. Prog., Victoria, B.C. and FORREX Forum for Research and Extension in Natural Resources, issue: 66,

2009

• Weiler, Markus
  Field based observation of hydrological processes
  In: Treatise on Water Science
  2009, Elsevier, issue: 2, page: in press,
• Leibundgut, C.
  Grundzüge der Wiesenbewässerung in der Oberheinebene - historisch und gegenwärtig
  In: Das Natur- und Landschaftsschutzgebiet Elzwiesen. Herausragendes Naturpotential einer alten Kulturlandschaft
  2009, Regierungspräsidium Freiburg, Fachschaft für Ornithologie Südlicher Oberrhein im NABU Deutschland, pages: 29 - 52,
• Markus Weiler
  Hydrologie
  In: Physische Geographie
  2009, Westermann, pages: 327 - 356, ISBN: 978-3-14-160354-5
• Lange, J., Kohn, I., Gunkel, A.
  Hydrologischer Wandel in Karstgebieten des östlichen Mittelmeerraums: vom Prozessverständnis zu belastbaren Prognosen
  In: Forum für Hydrologie und Wasserbewirtschaftung
  2009, Forum für Hydrologie und Wasserbewirtschaftung, Fachgemeinschaft Hydrologische Wissenschaften, volume: 26.09, pages: 89 - 94, Fachgemeinschaft Hydrologische Wissenschaften, ISBN: 978-3-941089-54-9
• Gregoire, Caroline, Elsaesser, David, Huguenot, David, Lange, Jens, Lebeau, Thierry, Merli, Annalisa, Mose, Robert, Passeport, Elodie, Payraudeau, Sylvain, Schuetz, Tobias, Schulz, Ralf, Tapia-Padilla, Gabriela, Tournebize, Julien, Trevisan, Marco, Wanko, Adrien
  Mitigation of Agricultural Nonpoint-Source Pesticide Pollution in Artificial Wetland Ecosystems – A Review
  In: Climate Change, Intercropping, Pest Control and Beneficial Microorganisms
  2009, Springer Netherlands, volume: 2, pages: 293 - 338, ISBN: 978-90-481-2715-3

2008

• Stahl, K., Van Lanen, H., Uhlenbrook, S.
  Processes and Regimes
  In: Manual on low flow estimation and prediction
  2008, World Meteorological Organization, issue: 50, page: 136,
• Stahl, K.
  Transboundary Rivers
  In: Manual on Low Flow Estimation and Prediction
  2008, World Meteorological Organization, issue: 50, page: 136,
• Leibundgut, Ch., Lischewski, B.
  Zur Wiesenbewässerung am Oberrhein
  In: Historische Wassernutzung an Donau und Hochrhein sowie zwischen Schwarzwald und Vogesen
  2008, Schriften der Deutschen Wasserhistorischen Gesellschaft (DWhG) e.V., pages: 239 - 248, ISBN: 978-3-8334-8273-1

2007

• Steinbrich, A.
  Biologische Gewässergüte Fließgewässer (2004)
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 8.4,
• Steinbrich, A.
  Blitze - Gewitter - Starkniederschläge
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 2.14,
• Waldmann, F., Lehle, M., Steinbrich, A.
  Bodenschätzung
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 4.16,
• Kern, F.-J.
  Flächenversiegelung
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 6.2,
• Kern, F.-J.
  Gewässernetzdichte
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 3.5,
• Steinbrich, A.
  Gewässerstruktur (2004)
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 8.6,
• Steinbrich, A., Dietzer, B.
  Niederschlags- und Klimastationen
  In: Wasser- und Bodenatlas Baden-Württember
  2007, Umweltministerium Baden-Württemberg, page: Kartentafel 2.1,
• Ihringer, J., Steinbrich, A.
  Regionalisierte Mittlere Abflussspende (Mq)
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 3.6,
• Ihringer, J., Kern, F.-J.
  Regionalisierte Mittlere Niedrigwasserabflussspende (MNQ)
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 3.7,
• Steinbrich, A.
  Saisonalität von Hochwasser und Starkniederschlägen
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 3.9,
• Kern, F.-J.
  Trockenheitsindex
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 6.4,
• Steinbrich, A., Kern, F.-J., Krenzke, S.
  Wassergewinnung und Wasserverwendung insgesamt
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 7.3,
• Kern, F.-J., Steinbrich, A.
  Wasserhaushalt von Einzugsgebieten
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 6.3,
• Kern, F.-J., Steinbrich, A., Krenzke, S.
  Öffentliche Wasserversorgung - Wassergewinnung nach Wasserarten
  In: Wasser- und Bodenatlas Baden- Württemberg
  2007, Umweltministerium Baden- Württemberg, page: Kartentafel 7.2,

2006

• Lange, J., Hänsler, A., Hugenschmidt, C.
  Hydrologische Prozessforschung bei Niedrigwasser in bewaldeten Einzugsgebieten - Einblick in die Funktionsweise bei extremen Dürreereignissen
  In: Tag der Hydrologie
  2006, , pages: 133 - 142,
• Maloszewski, P., Moser, H., Stichler, W., Trimborn, P.
  Nachweis von Wasserbewegungen, Verdunstungsvorgängen und Wasserneubildung mit Hilfe der Umweltisotope 2H und 18O
  In: Langzeitgefährdung der Trinkwasservorkommen durch Abfalldeponien, Abfallwirtschaft in Forschung und Praxis
  2006, E. Schmidt Verlag, pages: 65 - 90,

Conference papers

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2020

• Steinbrich, A., Leistert, H., Stoelzle, M., Weiler, M.
  Weichenstellung im Untergrund – vom Baseflow-Index zum Grundwasser-Neubildungs-Index?
  2020 Tag der Hydrologie, volume: 42, issue: 20, pages: 93 - 96
  
   
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2019

• Blume, T., Beiter, D., Weiler, M.
  Can we characterize hillslope-stream connectivity based on a joint event analysis of stream and groundwater?
  2019 American Geoscience Union Fall Meeting
• Schwemmle, R., Hartmann, A., Beck, H.
  Climatic and Physiographic Controls on Errors of Large-scaleHydrological Models
  2019 EGU General Assembly, volume: 21
• Orlowski, N., Seeger, S., Weiler, M., Rinderer, M.
  Comparing tree species-specific water uptake strategies via continuous in-situ monitoring of stable water isotopes
  2019 American Geoscience Union Fall Meeting
• Paulus, S., Kübert, A., Dahlmann, A., Werner, C., Rothfuss, Y., Dubbert, M., Orlowski, N.
  Comparison between destructive andin situmonitoring methods ofdetermination of soil pore water isotopic compositions for addressingecohydrological questions
  2019 EGU General Assembly, volume: 21
• Herbstritt, B., Seeger, S., Rinderer, M., Weiler, M.
  Continuous real-time analysis of water stable isotopes in ecohydrology
  2019 IAEA International Symposium on Isotope Hydrology (CN-271)
• Hellwig, J., Stahl, K., Weiler, M., de Graaf, I.
  Deutschlandweite Reaktion der Grundwasserkörper auf Dürre verschiedener Zeitskalen
  2019 Tag der Hydrologie
• Weiler, M., Steinbrich, A.
  Grundwasserflurabstand – wichtig für Modelle und Risiko- abschätzung, aber noch Potential in der räumlichen Modellierung
  2019 Tag der Hydrologie
• Hellwig, J., de Graaf, I., Weiler, M., Stoelzle, M., Stahl, K.
  Heterogeneity of Groundwater Responses to Climate Dynamics and Implications for Groundwater Droughts
  2019 American Geoscience Union Fall Meeting
• Blume, T, Demand, D., Sohrt, E., Beiter, D., Weiler, M.
  Hydrological event response analysis: how much data is necessary toidentify differences across landscape units?
  2019 EGU General Assembly, volume: 21
• Mälicke, M., Hassler, S., Weiler, M., Blume, T., Zehe, E.
  Hydrologische Ähnlichkeit dynamischer Bodenfeuchtemuster
  2019 Tag der Hydrologie
• Gralher, B., Herbstritt, B., Weiler, M., Wassenaar, C., Stumpp, C.
  Identifying and correcting the gas matrix effects on a cavity ring-down water stable isotope analyzer
  2019 IAEA International Symposium on Isotope Hydrology (CN-271)
• Rinderer, M., Seeger, S., Herbstritt, B., Weiler, M.
  Isotopes and water flow dynamics – Is the thrill already gone? The addedvalue of high-frequent isotope data for understanding soil water flow
  2019 EGU General Assembly, volume: 21
• Stahl, K., Blauhut, V., Stoelzle, M., Tijdeman, E., Menzel, L., Lange, J.
  Linking multi-sectorial impacts to hydrometeorological extremes duringthe drought of 2018 in Germany
  2019 EGU General Assembly, volume: 21
  
   
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• Weiler, M.
  Linking soil hydrology to rainfall probability - which conditions canproduce a 100-year flood event
  2019 Geophysical Research Abstracts, volume: 21
• Jeřábek, J., Rinderer, M., Weiler, M., Gessler, A.
  Novel use of microdialysis for high frequent phosphate sampling in xylemsap of beech trees
  2019 EGU General Assembly, volume: 21
• Herbstritt, B., Gralher, B., Weiler, M.
  Real-time observations of water stable isotope dynamics during rainfall and throughfall events
  2019 IAEA International Symposium on Isotope Hydrology (CN-271)
• Haag, I., Aigner, D., Krumm, J., Regenauer, J., Steinbrich, A., Weiler, M.
  Simulation von Hochwassern in der Folge von Starkregen mit LARSIM - ein Beispiel für die zielführende Nutzung vorhandener Bodendaten
  2019 Tag der Hydrologie
• Steinbrich, A., Leistert, H., Schuetz, T., Weiler, M.
  Städte - Stadtplanung und die Variabilität des Wasserhaushaltes – neue Modelle und Daten zur detaillierten Vorhersage des urbanen Wasserhaushaltes in Stadtteilen Freiburgs
  2019 Tag der Hydrologie
• Stoelzle, M., Weiler, M., Schuetz, T., Stahl, K.
  Streamflow components beyond binary quick-/baseflow separation
  2019 EGU General Assembly, volume: 21
• Orlowski, N., Kattenstroth, B., Lange, J., Weiler, M.
  The beauty of long-term hydrological datasets: Showcasing four different catchments in South-Western Germany
  2019 American Geoscience Union Fall Meeting
• Gatzert, X., Boner, M., Hermanowski, R., Mäder, R., Gattinger, A., Orlowski, N.
  Tracking regional authenticity of foodstuffs by means of stable isotopes
  2019 EGU General Assembly, volume: 21
• Demand, D., Weiler, M.
  Using the Stokes flow physical principles to define an appropriate scale for infiltration modelling
  2019 EGU Leonardo Conference
• Rinderer, M., Seeger, S., Herbstritt, B., Weiler, M.
  Wasser und Phosphor auf der Spur: Neue Messverfahren zur zeitlich hochaufgelösten Beobachtung von Wasser- und Nährstoffflüssen in Waldstandorten
  2019 Tag der Hydrologie

2018

• Lange, J., Greiwe, J., Müller, B., Hensen, B., Kümmerer, K., Olsson, O.
  Abflussverhältnisse steuern die Retention von Pestiziden und hydrologischen Tracern in Feuchtflächen
  2018 Tag der Hydrologie, volume: Heft 39.18, pages: 271 - 280
• Demand, D., Weiler, M.
  Alternative Concepts to Model Flow in the Unsaturated Zone – Can the Stokes Flow Concept for Modelling Preferential Flow be Applied to a Sensor Network at the Catchment-Scale?
  2018 AGU Fall Meeting
• Orlowski, N., Pratt, D., Breuer, L., Weiler, M., McDonnell, J. J.
  An isotopic comparison of waters obtained by destructive and non-destructive methods to evaluate mixing and runoff processes at the mini-hillslope scale
  2018 EGU General Assembly
• Schaffitel, A., Schuetz, T., Weiler, M.
  Assessing the water balance of paved surfaces with soil moisture observations
  2018 EGU General Assembly
• Henrichs, M., Scherer, I., Steinbrich, A., Leistert, H., Schuetz, T., Weiler, M., Brendt, T., Uhl, M.
  Bestimmung des Referenzzustandes für den urbanen Wasserhaushalt Regenwasser in urbanen Räumen
  2018 Regenwasser in urbanen Räumen aqua urbanica trifft RegenwasserTage 2018, volume: Schriftenreihe Wasser Infrastruktur Ressourcen · Band 1
• Demand, D., Blume, T., Selker, J., Weiler, M.
  Beyond classical infiltration - using Stokes flow in a diverse landscape
  2018 EGU General Assembly
• Staudinger, M., Stoelzle, M., Seeger, S., Seibert, J., Weiler, M., Stahl, K.
  Catchment water storage increases with elevation
  2018 EGU General Assembly
• Seeger, S., Rinderer, M., Herbstritt, B., Weiler, M.
  Delayed water uptake of European beech detected by in-situ measurements of stable water isotopes
  2018 EGU General Assembly
• Greiwe, J. , Müller, B. , Hensen, B., Olsson, O., Lange, J.
  Discharge conditions control the retention of pesticides and hydrologic tracers in wetland buffer systems
  2018 EGU General Assembly
• Brinkmann, N. , Buchmann, N., Eugster,W. , Seeger, S. , Weiler, M., Kahmen, A.
  Employing stable isotopes to determine the residence times of soil water and the temporal origin of water taken up by Fagus sylvatica and Picea abies in a temperate forest
  2018 EGU General Assembly
• Bork, M., Lange, J., Graf-Rosenfellner, M., Hensen, B., Olsson, O., Lang, F.
  Evaluation of the retention of organic pollutants in urban swale-trench systems by fluorescent tracers
  2018 EGU General Assembly
• Lange, J., Olsson, O., Sweeny, B., Herbstritt, B., Reich, M., Alvarez-Zaldivar, P., Payraudeau, S., Imfeld, G.
  Fluorescent tracers to evaluate pesticide dissipation and transformation in agricultural soils
  2018 EGU General Assembly
• Herbstritt, B., Seeger, S., Rinderer, M., Weiler, M.
  Low cost water vapour sampling for mobile in-situ measurements of stable water isotopes
  2018 EGU General Assembly
• Blume, T., Demand, D., Schneider, A.-K., van Schaik, L., Weiler, M.
  Monitoring preferential flow and macropore structures at the landscape scale – causes, characteristics and consequences
  2018 AGU Fall Meeting
• Ries, F., Kirn, L., Steinbrich, A., Weiler, M.
  Nicht jedes hundertjährliche Niederschlagsereignis generiert Abfluss – Erfahrungen aus großskaligen Starkregenversuchen in Baden-Württemberg
  2018 Tag der Hydrologie
• Kaplan, N., Sohrt, E., Blume, T., Weiler, M.
  Observing and predicting streamflow intermittency across a mesoscale catchment
  2018 EGU General Assembly
• Olsson, O., Hensen, B., Lange, J., Ulrich, U., Pfannerstill, M., Steinmann, F., Kümmerer, K.
  Pestizidrückstände in ländlichen und urbanen Grund- und Oberflächengewässern
  2018 51. Essener Tagung für Wasserwirtschaft „Wasserwirtschaft im Umbruch", volume: Band 247, pages: 55/1 - 55/11
• Vollert, D., Gassmann, M., Lange, J., Kümmerer, K., Olsson, O.
  Simulating the fate and release of metazachlor and its transformation products metazachlor oxalic acid and sulfonic acid in a small-scale agricultural catchment
  2018 EGU General Assembly
• Demand, D., Blume, T., Ries, F., Huisman, J. A., Weiler, M.
  Soil Crack Dynamics as Driver for Preferential Flow in Clay-Rich Soils
  2018 AGU Fall Meeting
• Orlowski, N., Weiler, M.
  Stabile Wasserisotope in der kritischen Zone: Chancen und Herausforderungen bei Methodenentwicklungen und Anwendungen
  2018 Tag der Hydrologie
• Orlowski, N., Pratt, D., Weiler, M., McDonnell, J. J.
  Stable isotopes of water in the subsurface: Opportunities and challenges in method developments and applications
  2018 AGU Fall Meeting
• Rinderer, M., Seeger, S., Jerabek, J., Gessler, A., Weiler, M.
  Subsurface flow dynamics and nutrient transport in forest stands – results from a large-scale sprinkling experiment
  2018 EGU General Assembly
• Blume, T., Beiter, D., Demand, D., Sohrt, E., Sprenger, M., Weiler, M.
  The value of long-term observations for hydrological event response analysis
  2018 AGU Fall Meeting
• von Freyberg, J., Allen, S. T., Seeger, S., Weiler, M., Kirchner, J. W.
  Using young water fractions to identify streamflow generation mechanisms across 22 Swiss catchments
  2018 EGU General Assembly
• Leistert, H., Steinbrich, A., Schütz, T., Weiler, M.
  Wie kann die hydrologische Komplexität von Städten hinreichend in einem Wasserhaushaltsmodell abgebildet werden?
  2018 Tag der Hydrologie, volume: Heft 39.18, pages: 227 - 235

2017

• Kaplan, N., Blume, T., Weiler, M.
  Abfluss in intermittierenden Bächen: Neue experimentelle Ansätze basierend auf photographischer Fernerkundung
  2017 Tag der Hydrologie
• Regenauer, J., Priesack, E., Schrempp, S., Hölscher, A., Puhlmann, H., Lange, J.
  Auswirkungen von Trockenperioden auf die Nitratauswaschung: Ein Vergleich von Acker- und Waldstandorten
  2017 Tag der Hydrologie, volume: 38.17, pages: 193 - 204
• Herbstritt, B., Rinderer, M., Weiler, M.
  Diffusion-tight bags for repeated discrete soil and xylem water vapor isotope sampling
  2017 EGU Leonardo - Water stable isotopes in the hydrological cycle
• Demand, D., Blume, T., Weiler, M.
  Infiltration Processes and Flow Velocities Across the Landscape: When and Where is Macropore Flow Relevant?
  2017 AGU Fall Meeting
• Jeřábek, J., Herbstritt, B., Rinderer, M., Gessler, A., Weiler, M.
  Investigating water and nutrient uptake by trees with in-situ measurements of water stable isotopes and phosphate in xylem
  2017 EGU Leonardo - Water stable isotopes in the hydrological cycle
• Fernández-Pascual, E., Zaman, S., Lang, F., Lange, J.
  Long-term mesocosm experiments to investigate degradation of fluorescent trancers
  2017 EGU General Assembly
• Rinderer, M., van Meerveld, I., McGlynn, B
  Measuring and modeling spatio-temporal patterns of groundwater storage dynamics to better understand nonlinear streamflow response
  2017 EGU General Assembly
• Seeger, S.
  Monitoring the water uptake of European beech with in-situ meausrements of stable water isotopes in the stem xylem
  2017 EGU Leonardo - Water stable isotopes in the hydrological cycle
• Rinderer, M., Ali., G., Larsen, L.
  Quantifying hydrologic connectivity with measures from the brain neurosciences – a feasibility study
  2017 EGU General Assembly
• Demand, D., Blume, T., Weiler, M.
  Räumliche und zeitliche Variabilität von Infiltrationsverhalten und präferenziellem Fluss in einem mesoskaligen Einzugsgebiet
  2017 Tag der Hydrologie
• Weiler, M., Pohl, S., Steinbrich, A.
  Starkregenrisikomanagement – Untersuchungen in Pilotgebieten
  2017 6. KLIWA-Symposium, pages: 170 - 179
• Seeger, S., Brinkmann, N., Kahmen, A., Weiler, M.
  Tree specific traits vs. stand level characteristics - assessing the source depths of plant water uptake in a mixed forest stand
  2017 EGU General Assembly
• Schaffitel, A., Schuetz, T., Weiler, M.
  Untersuchungen zum Infiltrationsverhalten verschiedener teilversiegelter urbaner Flächen
  2017 Tag der Hydrologie, volume: 38.17, page: 75–87
• Stahl, K.,, Kohn, I., Böhm, M., Freudiger, D., Gerlinger, K., Seibert, J., Weiler, M.
  Veränderungen der Abflusskomponenten aus Schnee- und Gletscherschmelze in Niedrigwassersituationen am Rhein
  2017 Tag der Hydrologie, volume: 38.17, pages: 217 - 226

2016

• Schmidt, S., Ries, F., Sauter, M.
  Evaluation of rapid recharge processes and spring source vulnerability of karst aquifers in semi-arid environments
  2016 AGU Fall Meeting
• Freudiger, D., Weiler, M., Kohn, I., Stahl, K.
  A combined dataset of glacier outlines from digitized historical maps and remote sensing and its application in hydrology
  2016 Tag der Hydrologie
• Kaplan, N., Weiler, M., Blume, T.
  A new image based approach to measure discharge and soil saturation
  2016 EGU General Assembly
• Demand, D., Weiler, M.
  A novel experiment for measuring infiltration into seasonally frozen soil
  2016 EGU General Assembly, volume: 18
• Steinbrich, A., Weiler, M.
  Ableitung zeitlich hoch aufgelöster Niederschlagszeitreihen aus RADOLAN-Niederschlagsdaten
  2016 Forum für Hydrologie und Wasserbewirtschaftung, volume: 37, issue: 16, pages: 107 - 117
• Klier, C.C., Schuetz, T., Untenecker, J., Bechtold, M.
  Assessing water table dynamics of peatland areas using Landsat TIR imagery
  2016 EGU General Assembly, volume: 18
• Schmidt, S., Ries, F., Doummar J., Sauter, M.
  Bestimmung schneller Grundwasserneubildungsprozesse und quantitativer Quell-Vulnerabilität für Karbonatgrundwasserleiter im semi-ariden östlichen Mittelmeerraum
  2016 Jahrestagung 2016 der Fachsektion Hydrogeologie in der Deutschen Gesellschaft für Geowissenschaften
• Hannaford, J., Stahl, K., Bachmair, S., Tijdeman, E., Collins, K., Svoboda., M., Knutson., C. L., Wall., N., Smith, K. S., Bernadt. T., Crossman., N. D., Overton., I. C., Barker, L. J., Acreman, M. C.
  Building Better Drought Resilience Through Improved Monitoring and Early Warning: Learning from Stakeholders in Europe, the USA, and Australia
  2016 AGU Fall Meeting
• Stahl, K., Kohn, I., Boehm, M., Freudiger, D., Gerlinger, K., Seibert, J., Weiler, M.
  Centurial changes in the augmentation of low flows by snow and glacier melt in the River Rhine
  2016 EGU General Assembly, volume: 18
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• Kohn, I., Vis, M. , Freudiger, D., Seibert, J., Weiler, M., Stahl, K
  Constraining the long-term hydrological modelling of the glaciated headwater catchments of the River Rhine
  2016 Tag der Hydrologie
• Herbstritt, B., Weiler, M.
  Continuous observation of tree interception effects on water stable isotopes
  2016 JOINT EUROPEAN STABLE ISOTOPES USER group MEETING (JESIUM)
• Schuetz, T., Hegenauer, A. M.
  Controls of catchments` sub-storage contributions to dynamic water quality patterns in the stream network
  2016 EGU General Assembly, volume: 18
• Schwab, M., Klaus, J., Pfister, L, Weiler, M.
  DOC and nitrate export linked to dominant rainfall-runoff processes, end-members and seasonality - a long-term high frequency measurement campaign
  2016 AGU Fall Meeting
• Jackisch, N., Brendt, T., Weiler M.
  Der Einfluss von Bäumen und Gründächern auf Abflussbildung und Wasserbilanz im Stadtteil Vauban (Freiburg)
  2016 IKT-Forum: Niederschlagswasser, Vegetation & Infrastruktur 2016 –Regenwasser in der Stadt, page: 19
• Bachmair, S., Svensson, C., Prosdocimi, I., Hannaford, J., Helm Smith K., Svoboda, M., Stahl, K.
  Drought impact functions as intermediate step towards drought damage assessment
  2016 EGU General Assembly, volume: 18
• Hoffmann, A., Weiler, M.
  Environmental monitoring with a new UAV based multi-sensor system
  2016 AGIT
• Seeger, S., Weiler, M.
  Estimating plant water uptake source depths with optimized stable water isotope labeling
  2016 EGU General Assembly
• Blume, T., Heidbüchel, I., Simard, S., Gunther, A., Weiler, M.
  Forest Transpiration: Resolving Species-Specific Root Water Uptake Patterns
  2016 AGU Fall Meeting
• Gerlinger, K., Böhm, M., Stahl, K., Weiler, M., Kohn, I., Freudiger, D., Seibert, J., Vis, M.
  Gerlinger, K., Böhm, M., Stahl, K., Weiler, M., Kohn, I., Freudiger, D., Seibert, J., Vis, M. 2016. Modellbasierte Quantifizierung der Abflussanteile aus Regen, Schnee- und Gletscherschmelze im Rheineinzugsgebiet im Zeitraum von 1901 bis 2006
  2016 Tag der Hydrologie
• Hartmann, A.
  Herausforderungen des Grundwasserschutz in Karst Gebieten (Invited Presentation)
  2016 Frühjahrstagung der Schweizerische Gesellschaft für Hydrogeologie SGH
• Volkmann, T., Haberer, K., Troch, P., Gessler, A., Weiler, M.
  High-resolution stable isotope monitoring reveals differential vegetation–soil water feedbacks among plant functional types (Invited)
  2016 AGU Fall Meeting
• Sarrazin, F., Hartmann, A., Pianosi, F., Wagener T.
  How much does subsurface heterogeneity alter the impact of climate and land use changes on groundwater recharge?
  2016 EGU General Assembly, volume: 18
• Bachmair, S., Tanguy, M., Hannaford, J., Stahl, K.
  How useful are meteorological drought indicators to assess agricultural drought impacts across Europe?
  2016 EGU General Assembly, volume: 18
• Tijdeman, E., Hannaford, J., Stahl, K., Svoboda, M.
  Human influences affect streamflow drought characteristics in the UK and US
  2016 AGU Fall Meeting
• Kohn, I., Vis, M. , Freudiger, D., Seibert, J., Weiler, M., Stahl, K.
  Hydrological modelling of alpine headwaters using centurial glacier evolution, snow and long-term discharge dynamics
  2016 EGU General Assembly, volume: 18
• Hartmann, A.
  Impact of wind throws on water quality and quantity at an alpine forest at the Kalkalpen National Park (Invited Presentation)
  2016 Forstwissenschaftliches Seminar am Freiburger Institut für Forstwissenschaften
• Kirn, L., Mudarra, M., Marín, A., Andreo, B., Hartmann, A.
  Improved Assessment of Groundwater Recharge in a Mediterranean Karst Region: Andalusia, Spain
  2016 EuroKarst, pages: 117 - 125
• Barker, L., Hannaford, J., Tijdeman, E., Laize, C.
  Improving drought monitoring and early warning for water resource management in the UK: an impact focused approach
  2016 AGU Fall Meeting
• Weiler, M., Lieder, E., Blume, T.
  Interplay of Geology, Vegetation and Mankind Controlling Patterns and Dynamics of Thermal Riverscapes (Invited)
  2016 AGU Fall Meeting
• Hartmann, A. , Baker, A.
  Overview of karst modelling approaches and their relevance for paleoclimate reconstruction
  2016 EGU General Assembly, volume: 18
• Hartmann, A.
  Parameter estimation and model evaluation in karst regions - A balance of data availability and process representation (Invited Keynote Lecture)
  2016 Peter Wolf Symposium of the British Hydrological Society
• Freudiger, D., Weiler, M.
  Potential of Satellite Images for Snow Redistribution in Hydrological Models
  2016 AGU Fall Meeting
• Stahl, K., Kohn, I., Böhm, M., Seibert, J., Freudiger, D., Gerlinger, K., Weiler, M.
  Quantifying changes in the contribution of upstream snow and glacier melt to downstream low flows in the River Rhine
  2016 AGU Fall Meeting
• Smith, K., Tijdeman, E., Bachmair, S., Barker, L., Knutson, C., Wall, N., Bernadt, T., Stahl, K.
  Reconstructing droughts beyond the hydro-meteorological indicators: a qualitative analysis to show what we can learn from Impacts in the US Drought Impact Reporter
  2016 AGU Fall Meeting
• Ries, F., Schmidt, S. , Sauter, M., Lange, J.
  Runoff generation in a Mediterranean semi-arid landscape: Thresholds, scale, rainfall and catchment characteristics
  2016 EGU General Assembly, volume: 18
• Koelbing, M., Schuetz, T., Weiler, M.
  Spatial impacts of urban structures on micrometeorological variables
  2016 EGU General Assembly, volume: 18
• Stölzle, M., Steinbrich, A., Weiler, M.
  Starkregengefährdung in Baden-Württemberg – von der Methodenentwicklung zur Starkregenkartierung
  2016 Tag der Hydrologie, volume: 37.16
• Berghuijs, W., Hartmann, A., Woods, R
  Streamflow sensitivity to water storage changes across Europe
  2016 EGU General Assembly, volume: 18
• Heudorfer, B., Stahl, K.
  Towards a method to characterize groundwater dynamics during drought
  2016 EGU General Assembly, volume: 18
• Leibundgut, C., Vonderstrass, I.
  Trad. Bewässerung: Wirkungen auf Böden und Biologie - Erhaltungstrategie Kulturerbe
  2016 Wiesenlandschaften mit hohem Wert für Mensch und Natur
• Vonderstrass, I., Leibundgut, C.
  Traditionelle Bewässerung. Erhaltungsstrategie Kultureerbe
  2016 Wiesenlandschaften mit hohem Wert für Mensch und Natur
• Hartmann, A., Gleeson, T., Wada, Y., Wagener, T.
  Transit time distributions to assess present and future contamination risk of karst aquifers over Europe and the Mediterranean
  2016 EGU General Assembly, volume: 18
• Heudorfer, B., Stahl, K.
  Untersuchung der Fortpflanzung von Trockenwettersignalen mithilfe verschiedener Schwellenwertmethoden
  2016 Tag der Hydrologie
• Weiler, M.
  Urban RoGeR: Merging process-based high-resolution flash flood model for urban areas with long-term water balance predictions
  2016 AGU Fall Meeting
• Bachmair, S., Kohn, I., Blauhut, V., Stahl, K
  Verknüpfung von Trockenheitsindikatoren mit berichteten Auswirkungen durch Trockenheit
  2016 Tag der Hydrologie
• Stoelzle, M., Weiler, M.
  Winter streamflow analysis in frozen, alpine catchments to quantify groundwater contribution and properties
  2016 EGU General Assembly, volume: 18

2015

• Steinbrich, A., Weiler, M., Leistert, H.
  Alles RoGeR? Modellierung von Sturzfluten aufgrund von Starkniederschlägen
  2015 Forum für Hydrologie und Wasserbewirtschaftung, volume: 35, issue: 15, pages: 115 - 125
• Stahl, K., Kohn, I., De Stefano, L., Tallaksen, L.M ., Rego, F.C., Seneviratne, S.I., Andreu, J., Van Lanen, H.A.J.
  An impact perspective on pan-European drought sensitivity
  2015 Drought: Research and Science-Policy Interfacing
• Blauhut, V., Stahl, K., Vogt, J.
  Assessing risk by impacts: a probabilistic approach for drought assessment in Europe
  2015 EGU 2015, volume: 17
• Tallaksen, L.M., Stagge, J.H., Stahl, K., Gudmundsson, L., Orth, R., Seneviratne, S., Van Lanen, H. A. J., Van Loon, A. F
  Characteristics and drivers of drought in Europe – a summary of the DROUGHT-R&SPI project
  2015 Drought: Research and Science-Policy Interfacing
• Blauhut, V., Stahl, K.
  Drought risk on a pan European scale: integrating the missing piece
  2015 EGU 2015, volume: 17
• Garvelmann, J., Pohl, S., Mair E., Marke, T., Strasser, U., Warscher, M., Kunstmann, H.
  Evaluation of algorithms for calculating forest micrometeorological variables using an extensive dataset of paired station recordings
  2015 AGU Fall Meeting
• Van Lanen, H.A.J., Tallaksen, L.M., Stahl, K., Assimacopoulos, D., Wolters, W., Andreu, J., Rego, F., Seneviratne, S.I., De Stefano, L., Massarutto, A., Garnier, E., Seidl, I.
  Fostering Drought Research and Science-Policy Interfacing: Achievements of the DROUGHT-R&SPI project
  2015 Drought: Research and Science-Policy Interfacing
• Sprenger, M., Erhardt, M., Riedel, M., Weiler, M.
  Historical tracking of nitrate in contrasting vineyard using water isotopes and nitrate depth profiles
  2015 AGU Fall Meeting 2015
• Tijdeman, E., Stahl, K., Bachmair, S.
  Impacts of anthropogenic activities on different hydrological drought characteristics
  2015 EGU
• Stoelzle, M., Schuetz,T., Weiler, M., Stahl, K., Seibert, J., Tallaksen, L.M.
  Improved baseflow characterization in mountainous catchments
  2015 EGU
• Pohl, S., Garvelmann, J., Weiler M.
  Observation of the Spatio-Temporal Variability of Snowmelt and Runoff Generation During Rain-on-Snow in a Catchment With Complex Terrain
  2015 AGU Fall Meeting
• Herbstritt, B., Gralher, B., Volkmann, T., Weiler, M.
  Real-time analysis of stable water isotopes in highly dynamic systems
  2015 IAEA International Symposium on IsotopeHydrology
• Stahl, K., Kohn, I., Blauhut, V. , Bachmair, S.
  Spatial and temporal variability of drought impact profiles across Europe
  2015 EGU 2015, volume: 17
• Blauhut, V., Stahl, K., Kohn, I.
  The dynamics of vulnerability to drought in Europe
  2015 International Conference Drought R&SPI 2015
• Bachmair, S., Stahl, K., Hannaford, J., Svoboda, M.
  Towards developing drought impact functions to advance drought monitoring and early warning.
  2015 EGU 2015, volume: 17

2014

• Stahl, K., Kohn, I., De Stefano, L., Tallaksen, L.M., Rego, F.C., Seneviratne, S.I., Andreu, J, Van Lanen, H.A.J.
  An impact perspective on pan-European drought sensitivity.
  2014 6th European Geosciences Union (EGU) Leonardo Conference: HYPER Droughts
• Stoelzle, M, Stahl, K, Weiler, M, Morhard, A, Schuetz, T
  Aquifer type-specific conceptual groundwater models improve baseflow simulation
  2014 EGU General Assembly 2014, volume: 16, pages: EGU2014 - 739
• Urquijo, J., De Stefano, L., González-Tánago, I., Blauhut and V., Stahl, K.
  Assessing Vulnerability to Drought on a pan–European scale
  2014 EGU 2014, volume: 16
• Stahl, K., Hannaford, J., Svoboda, M., Knutson, C.L., Bachmair, S., Acreman, M., Crossman, N.D., Overton, I.C., Colloff, M., Collins, K.
  Building resilience to drought impacts on water supplies: a comparison of approaches in Europe, the USA, and Australia.
  2014 AGU Fall Meeting
• Stahl, K.
  Challenging large-scale hydrological simulations with streamflow observations: response versus persistence.
  2014 AGU Fall Meeting
• Schmidt, S., Geyer, T., Guttman, J., Marei, A., Ries, F., Sauter, M.
  Characterisation of conduit restricted karst aquifers? A methodology demonstrated at the example of the Auja spring, Lower Jordan Valley
  2014 Karst without boundaries
• Schmidt, S., Geyer, T., Guttman, J., Marei, A., Ries, F., Sauter, M.
  Charakterisierung röhrengedrosselter Karstgrundwasserleiter
  2014 Jahrestagung 2014 der Fachsektion Hydrogeologie in der Deutschen Gesellschaft für Geowissenschaften (FH-DGG)
• Schwerdtfeger, J., Gripp, S.W.S., Zeilhofer, P., Weiler, M.
  Coupled ground- and satellite-based assessment of regional evaporation and ecosystem vulnerability in tropical wetlands.
  2014 American Geophysical Union (AGU)
• Hartmann, A., Kobler, J., Kralik, M., Dirnböck, T., Humer, F., Weiler, M.
  Deriving the time-variant transit time distributions of an Austrian karst system by a semi-distributed karst model.
  2014 EGU General Assembly
• Gimbel, K., Puhlmann, H., Weiler, M.
  Does drought alter hydrological functions in forest soils?
  2014 EGU General Assembly 2014, volume: 16
• Heudorfer, B., Stahl, K.
  Drought propagation analysis using different threshold level methods
  2014 6th European Geosciences Union (EGU) Leonardo Conference: HYPER Droughts
• Herbstritt, B., Gralher, B., Weiler, M.
  Effects of soil properties on the apparent water-vapor isotope equilibrium fractionation: Implications for the headspace equilibration method
  2014 Jahrestagung der Arbeitsgemeinschaft Stabile Isotope ASI
• Stahl, K., Weiler, M., Freudiger, D., Seibert, J.
  Empirische Analysen zur Klimasensitivität des Abflusses alpiner Kopfeinzugsgebiete
  2014 Trinationaler Workshop “Hydrologische Prozesse im Hochgebirge
• Bachmair, S., Stahl, K., Blauhut, V., Kohn, I.
  Exploring the link between drought indicators and impacts through data visualization and regression trees
  2014 EGU 2014, volume: 16
• Kohn, I., Stagge, J.H., Blauhut, V., Bachmair, S., Stahl, K., Tallaksen, L.M.
  Impacts of European drought events: insights from an international impact report inventory
  2014 EGU 2014, volume: 16
• Bachmair, S., Stahl, K. , Hannaford, J. , Barker, L., Kohn, I., Svensson, C., Tanguy, M.
  Linking drought indicators with impacts: Insights from a case study in Germany and the UK
  2014 6th European Geosciences Union (EGU) Leonardo Conference: HYPER Droughts
• Stagge, J.H, Kohn, I., Tallaksen, L.M., Stahl, K.
  Modeling drought impact occurrence based on climatological drought indices for Europe
  2014 AGU Fall Meeting
• Stagge, J.H., Kohn, I., Tallaksen, L.M., Stahl, K.
  Modeling drought impact occurrence based on climatological drought indices for four European countries
  2014 EGU 2014
• Steinbrich, A., Weiler, M.
  Modelling flood runoff generation scale independent and without calibration.
  2014 Computational Methods in Water Resources.
• Stölzle, Michael, Stahl, Kerstin, Morhard, Andreas, Weiler, Markus
  Recharge scenarios to identify controls of catchments’ sensitivity to drought
  2014 HYPER Droughts, 6. EGU Leonardo Conference
• Schuetz, T., Weiler, M., Gascuel-Odoux, C.
  Scale effects of nitrate sinks and sources in stream networks
  2014 EGU General Assembly 2014, volume: 16, pages: EGU2014 - 8564
• Hartmann, A., Gleeson, T., Wagener, T.
  Sensitivity of Mediterranean groundwater resources to potential climate futures.
  2014 EGU General Assembly
• Hartmann, A., Gleeson, T., Wagener, T., Wada, Y.
  Simulating subsurface heterogeneity improves large-scale water resources predictions
  2014 American Geophysical Union 2014 Fall Meeting
• Stahl, K., Vidal, J.P., Hannaford, J., Prudhomme, C., Laaha, G., Tallaksen, L.
  Synthesizing changes in low flows from observations and models across scales
  2014 FRIEND-Water Conference
• Stahl, K., Vidal, J.P., Hannaford, J., Prudhomme, C., Laaha, G., Tallaksen, L.
  Synthesizing changes in low flows from observations and models across scales
  2014 FRIEND-Water Conference
• Kohn, I., Stagge, J.H., Blauhut, V., Bachmair, S., Stahl, K., Tallaksen, L.M.
  The European Drought Impact report inventory EDII: major drought events
  2014 6th European Geosciences Union (EGU) Leonardo Conference: HYPER Droughts,
• Blauhut, V., Kohn, I., Stahl, K.
  The dynamics of vulnerability to drought in Europe
  2014 Drought: Research and Science-Policy Interfacing
• Blauhut, V., Gudmundsson, G., Stahl, K., Seneviratne, S.
  Towards drought risk mapping on a pan-European scale
  2014 EGU 2014, volume: 16
• Blauhut, V., Urquijo, J., González Tánago, I., Ballesteros, M., Stahl, K., De Stefano, L.
  Towards pan–European drought risk maps: comparing an impact-based approach with a factor-based vulnerability assessment
  2014 6th European Geosciences Union (EGU) Leonardo Conference: HYPER Droughts
• Hartmann, A., Gleeson, T., Rosolem, R., Pianosi, F., Wagener, T.
  Understanding recharge elasticity through large-scale simulations of Europe’s karst regions under varying climatic boundary conditions.
  2014 EGU General Assembly
• Sprenger, M., Weiler, M., Blume, T
  Water transit times in the unsaturated zone: Spatio-temporal variation and its application in for the characterization of functional units.
  2014 AGU Chapman Conference

2013

• Hartmann, A., Lange, J., Weiler, M., Arbel, Y., Greenbaum, N.
  Controls of spatial structural variability on lateral and vertical flow dynamics at the soil-bedrock interface in a karst system
  2013 AGU 2013 Fall Meeting
• Blauhut, V., Stahl, K.,, Kohn, I., EDII-contributors
  EDII - A European Drought Impact Report Inventory
  2013 European Climate Change Adaption Conference
• Külls, C.
  Ecohydrological principles in economic models of water resources in drylands and desert restoration
  2013 UNCCD, 2nd Scient. Conf.
• Stähli, M., Ritter, M.
  Hydrologische Trends in kleinen voralpinen Einzugsgebieten
  2013 Tag der Hydrologie 2013
  » show abstract« hide abstract
  Abstract

  Hydrologische Kenngrössen, wie z.B. Niederschlag, Abfluss und elektrische Leitfähigkeit sind in kleinen (~1km2) voralpinen Einzugsgebieten von hoher Variabilität. Umso schwieriger ist es, klare Aussagen zu langjährigen Trends solcher Kenngrössen zu machen. Dies auch darum, weil langjährige, zeitlich hochaufgelöste hydrologische Messungen in kleinen Einzugsgebieten – im Vergleich zu grossen und mesoskaligen Fliessgewässern – selten sind. Beispiel solcher langzeitlichen Untersuchungen sind drei Kleineinzugsgebiete im Alptal (Zentralschweiz, 1100-1500 m ü.M., Waldanteil: 20-60%), in welchen die Eidg. Forschungsanstalt WSL seit über vierzig Jahren Forschung zur Hochwasserbildung, Wasserqualität und Schneedecke betreibt. Hier zeigen wir erstmals umfassende Trendanalysen der zeitlich hochaufgelösten hydrologischen Kenngrössen der letzten 30-40 Jahre. Alle hydrologischen und meteorologischen Zeitreihen wurden hinsichtlich Datenlücken korrigiert und auf Monats- und Jahreswerte aggregiert. Zur Abschätzung der Trendrichtungen und- steigungen diente die Sen’s slope Methode, die Signifikanz der Trends wurde nach Mann-Kendall bestimmt. Hierbei wurden alle möglichen Start- und Endjahre der Zeitreihen mit einer Mindestlänge von 10 Jahren kombiniert. Die Ergebnisse dieser Analyse zeigen nur wenige signifikante (p < 0.05) Trends auf, welche in allen drei Einzugsgebieten gleichermassen zum Ausdruck kommen. Eindeutig ist eine Abnahme des Abflusses im Monat Mai seit den 1970-er Jahren, welcher der immer früheren und mengenmässig geringeren Schneeschmelze zuzuschreiben ist. Weniger deutlich, aber dennoch signifikant in allen drei Gebieten, hat der Abfluss im Monat September in der Zeit von 1985-2005 zugenommen, verbunden mit einer ebenfalls signifikanten Zunahme des Niederschlags in dieser Zeit. Für Jahresabfluss und -niederschlagsmengen sind die Trends nicht einheitlich oder wenig signifikant. Was die Wassertemperatur betrifft, fällt die in allen Gebieten übereinstimmende Zunahme im Frühsommer besonders ins Auge. Diese kann wiederum mit der früheren Ausaperung der Schneedecke und der damit verbundenen Abnahme des Abflusses im Mai erklärt werden. Trends der elektrischen Leitfähigkeit im Abfluss zeigen ein komplexes Muster. Dabei ist besonders wiederum im Frühsommer ein genereller Anstieg auffallend. Alles in allem bestätigen die Messdaten aus dem Alptal, dass (längerfristige) Änderungen im Klima durchaus in den hydrologischen Kenngrössen kleiner voralpiner Einzugsgebiete zum Ausdruck kommen. Betrachtet man den gesamten Zeitraum 1970 bis heute, in welchem die laufende Diskussion des Klimawandels entstanden ist, muss trotzdem festgehalten werden, dass die hydrologischen Änderungen in dieser Höhenzone noch wenig ausgeprägt sind. Jedoch sind insbesondere bei kürzeren Zeitreihenlängen (<20a) sowie für bestimmte Monate durchaus signifikante Änderungen des Wasserhaushalts, insbesondere der Schneeschmelze, zu beobachten.
• Sprenger, M., Gralher, B., Weiler, M.
  Identifying flow processes in catchments with porewater isotope profiles.
  2013 General Assembly
• Garvelmann, J., Pohl, S., Weiler, M.
  Influence of a vegetation cover on the snow melt energy balance measured with a high density snow monitoring station network
  2013 EGU General Assembly 2013, pages: EGU 2013 - 429
• Weiler, M., Steinbrich, A.
  Influences of temporal rainfall radar and spatial rainfall-runoff model resolution on flood prediction
  2013 EGU General Assembly , volume: 15, issue: EGU2013-10455
• Blauhut, V., Stahl, K., Gudmundsson, L., Seneviratne, S. I.
  Linking Drought Indices to Impacts of the 2003 drought even
  2013 European Climate Change Adaption Conference
• Blauhut, V., Stahl, K., Gudmundsson, L., Seneviratne, S. I.
  Linking Drought Indices to reported Impacts
  2013 EGU 2013, volume: 16
• Garvelmann, J., Pohl, S., Weiler, M.
  Measuring the snow melt energy balance during rain-on-snow with a high density snow monitoring station network
  2013 Davos Atmosphere and Cryoshere Assembly 2013
• Pohl, S., Garvelmann, J., Weiler, M.
  Monitoring the spatial and temporal variability of snow cover properties using a network of standalone sensors and time lapse cameras
  2013 EGU General Assembly 2013, volume: 15, pages: EGU2013 - 9796
• Stagge, J.H., Tallaksen, L.M., Gudmundsson, L., van Loon, A., Stahl, K.
  Pan-European comparison of candidate distributions for climatological drought indices, SPI and SPEI
  2013 EGU 2013, volume: 15
• Külls, C., Bittner, A.
  Passive barriers for long-term containment of Vanadium and Uranium
  2013 International Mine Water Association IMWA, Reliable Mine Water Technology, Proc., page: 5
• Van Lanen, HAJ, Van Loon, A.F., Van Huijgevoort, M., Wanders, N., Alderlieste, M.A.A., Stahl, K., Tallaksen, L.M.
  Past and future hydrological drought in water-scarce European regions
  2013 EGU 2013, volume: 15
• Sprenger, M., Weiler, M.
  Potential of pore water stable isotope for optimization of soil physical parameters and predicting flow and transport in the unsaturated zone.
  2013 AGU Fall Meeting 2013
• Schuetz, T., , M. Weiler, , M. Saroos
  Spatial and temporal water quality dynamics during baseflow in an agricultural headwater catchment
  2013 EGU General Assembly, volume: 15, pages: EGU2013 - 903-1
• Külls, C., Bittner, A.
  Strategic Assessment of Water Resources for the Erongo Uranium Province
  2013 International Mine Water Association IMWA, Reliable Mine Water Technology, Proc., page: 6
• Steinbrich, A., Weiler, M.
  Systematic deviation between COSMO-EU precipitation forecast and measured precipitation.
  2013 EGU General Assembly, volume: 15, issue: EGU2013-9549
• Hartmann, A.
  The challenge of predicting karst water resources in a changing world
  2013 AGU 2013 Fall Meeting
• Külls, C., Berkowicz, S., Costantini, E., Geissen, V., Kvaerno, S., Marton, L., Ritsema, C.
  The eco-hydrological perspective of desert restoration
  2013 UNCCD, 2nd Scient. Conf.

2012

• Weiler, M., Pohl, S., Garvelmann, J., Wawerla, J.
  A new low-cost ultrasonic and meteorological sensor for observation of snow hydrological processes
  2012 EGU General Assembly 2012, volume: 14, pages: EGU2012 - 11120
• Lange, J., Hartmann, A., Barberá, J. A., Andreo, B., Weiler, M.
  A new modeling and calibration approach considering time variant recharge areas in karst systems
  2012 AGU Union 2012 Fall Meeting
• Stoelzle, M., Stahl, K., Weiler, M.
  As simple as possible? Drought recognition based on streamflow recession
  2012 10th International Conference on Hydroinformatics
• Jackisch, N., Weiler, M.
  Assessing the hydrologic performance of an urban catchment that combines Stormwater Best Management Practices (BMPs) and Low Impact Development (LID)
  2012 Urban Drainage Modelling. Proceedings of the Ninth International Conference on Urban Drainage Modelling
• Ritter, M., Bachmair S., Weiler, M.
  Combined field- and model-based intercomparison of hillslope hydrological response under different vegetation covers
  2012 American Geophysical Union 2012 Fall Meeting, pages: H31G - 1199
• Pohl, S., Garvelmann, J., Weiler, M.
  Detaillierte Feldbeobachtung der räumlichen und zeitlichen Variabilität der Schneedeckeneigenschaften mit einem Netzwerk aus zahlreichen kostengünstigen Sensoren
  2012 Tag der Hydrologie 2012
• Gimbel, K., Puhlmann, H., Weiler, M.
  Effects of drought on forest soil structure and hydrological soil functions
  2012 EGU General Assembly 2012, volume: 14
• Jackisch, N., Brendt, T., Henkel, E., Lange, J.
  Funktioniert die Regenwasserversickerung so wie geplant? - Evaluierung anhand von Messungen im Stadtteil Vauban, Freiburg
  2012 11. DWA Regenwassertage
• Weiler, M., Herbstritt, B., Gralher, B.
  High frequency, realtime measurements of stable isotopes in liquid water
  2012 EGU General Assembly 2012, volume: 14, pages: EGU2012 - 11329
• Pohl, S., Garvelmann, J., Weiler, M.
  High resolution monitoring of spatial and temporal variability of mountain snow covers
  2012 CWRA-CGU National Conference 2012
• Külls, C.
  Kartographie von Wasserressourcen
  2012 Afrikatagung der deutschen Geowissenschaftler
• Lange, J., Kümmerer, K., Imfeld, G., Herbstritt, B., Maillard, E., Lefrancq, M., Gutowski, L., Durst, R., Steudten, R., Regazzoni, C., Gassmann, M., Payraudeau, S.
  Künstliche Feuchtflächen in Hochwasserrückhaltebecken – eine Chance für die Reduzierung von Pflanzenschutzmitteleinträgen in Gewässer
  2012 Tag der Hydrologie 2012, pages: 294 - 299
• Tallaksen, L.M., Stahl, K.
  Major historical droughts in Europe as simulated by an ensemble of large-scale hydrological models
  2012 EGU 2012, volume: 14
• Gimbel, K., Puhlmann, H., Weiler, M.
  Monitoring drought effects on soil structure and hydrological soil functions
  2012 Eurosoil
• Garvelmann, J., Pohl, S., Weiler, M.
  Monitoring of vegetation influences on snow processes in a mid-latitude mountainous environment
  2012 CWRA-CGU National Conference 2012
• Pohl, S., Garvelmann, J., Weiler, M.
  Observation of Vegetation Influences on Snow Processes using a High Density Monitoring Network
  2012 American Geophysical Union Fall Meeting 2012, pages: C14B - 06
• Pohl, S., Garvelmann, J., Weiler, M.
  Observation of the Difference in Snow Cover Evolution Between Open and Forested Areas
  2012 EGU General Assembly 2012, pages: EGU2012 - 9711
• Schuetz, T., , M. Weiler
  On-site visualization and analysis of hydrological processes using handheld thermal imaging.
  2012 IAHS 90th Anniversary PUB Symposium
• Garvelmann, J., Pohl, S., Weiler, M.
  Potential der Zeitraffer-Fotografie zur Beobachtung der räumlichen Verteilung von Schneedeckeneigenschaften
  2012 Tag der Hydrologie 2012
• Schuetz, T., , M. Weiler
  Quantitative Analyse von Grundwasserzutritten und Fließwegen im Flachwasser mittels Thermographie
  2012 Tag der Hydrologie
• Herbstritt, B., Gralher, B., Weiler, M.
  Realtime in-situ determination of d18O and d2H in liquid water
  2012 European Stable Isotope Users group Meeting JESIUM 2012
  » show abstract« hide abstract
  Abstract

  We developed a method to measure in-situ continuously the isotopic composition of liquid water with minimal supervision and with a previously unmatched temporal resolution of less than a minute. For this purpose an off-the-shelf microporous hydrophobic membrane contactor for under 200€ was combined with an isotope laser spectrometer (Picarro). The contactor, originally designed for degassing liquids, was used with nitrogen as carrier gas in order to transform a small fraction of liquid water to water vapor. The generated water vapor was then analyzed continuously by the isotope laser spectrometer. To prove the membrane’s applicability we determined the specific isotope fractionation factor for the phase change through the contactor’s membrane for a common temperature range and with different waters of known isotopic compositions. This fractionation factor is then used to derive the liquid water isotope ratio from the measured water vapor isotope ratios and the measured temperature at the phase change. The system performance was evaluated for tracer breakthrough curves in a soil column experiment with two isotopically distinct natural waters. The isotope values corresponded very well with those of liquid water samples taken simultaneously and analyzed by conventional means (CRDS). The introduced method supersedes taking liquid samples and employs only relatively cheap and readily available components. This makes it a relatively inexpensive, fast, user-friendly and easily reproducible method. It can be applied in both field and laboratory settings wherever a water vapor isotope analyzer can be run and whenever real-time isotope data of liquid water are required at high temporal resolution with the same accuracy as collecting individual water samples.
• Külls, C.
  Rekonstruktion hydrologischer Extreme in der Namibwüste
  2012 Ber. Naturf. Ges. Freiburg i. Br, volume: 101, pages: 69 - 82
• Leibundgut, Ch.
  Relevante Aspekte aus dem Nationalen Forschungsprogramm NFP 61 «Nachhaltige Wassernutzung»
  2012 Forum für Wissen 2012: Alpine Schnee- und Wasserressourcen - gestern, heute, morgen, page: 61–68
• Steinbrich, A., Weiler, M.
  Skalenübergreifende Modellierung der Abflussbildungsprozesse bei der Entstehung von Hochwasser mit dem Modell DROGen
  2012 Tag der Hydrologie, Wasser ohne Grenzen, volume: Heft 31.12, pages: 207 - 212
• Hartmann, A., Wagener, T., Rimmer, A., Lange, J., Brielmann, H.,, Weiler, M.
  Testing the realism of model structures to identify karst system processes using water quality and quantity signatures
  2012 AGU 2012 Fall Meeting
• Garvelmann, J., Pohl, S., Weiler, M.
  The application of time-lapse photography for the observation of snow processes in mountainous catchments
  2012 EGU General Assembly 2012, volume: 14, pages: EGU2012 - 10181
• Külls, C.
  Towards social self-regulation of hydrological systems
  2012 Leonardo conference on Society and Hydrology
• Külls, C.
  Vom Umgang mit Wasserknappheit in Trockengebieten
  2012 Abschlusssymposium des Projektverbundes „Global Change and Globalization”

2011

• Gudmundsson, L., Tallaksen, L.M., Wagener, T., Engeland, K., Stahl, K.
  Comparative Diagnostic Evaluation of eight Large Scale Hydrological Models Across Europe
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 6364
  » show abstract« hide abstract
  Abstract

  An ensemble of eight global hydrology models (GHM) and land surface models (LSM) was evaluated with respect to their ability to reproduce the hydroclimatic regime, defined as the mean annual cycle of observed monthly runoff. The ensemble was build as a joint effort within the European Union Framework program WATCH (eu-watch.org). All models are run using the WATCH forcing data (WFD) as meteorological input. Models differ in their process formulations as well as in their parameterizations. The models are evaluated against a pan-European data set of more than 400 observed runoff series from small near-natural catchments. The diagnostic model evaluation was based on decomposing the mean squared error into bias, variance and a component attributed to errors in correlation. Each component has its own hydrological interpretation. The bias measures error in mean. The variance measures whether the amplitude of the annual cycle is reproduced accurately. The correlation-error quantifies differences in hydrograph shape and is thus sensitive to differences in timing between the observed and the modeled annual cycles. The model performance differs significantly among the different models and hydroclimatic regimes. On average, the ensemble mean provided the most reliable estimate for the mean annual cycle. The signature of the decomposed mean square error varies systematically between the different hydroclimatic regimes and the best performing models differ for the different error components. In this talk we will present how an systematic analysis of variations in the error components allows for a diagnostic evaluation of the model structures included in the comparison. In summary, we found that deficiencies in the modeling of complex but relevant hydrological processes, such as snow melt, does not only lead to significant differences in performance between different models, but also causes systematic differences in the error structure, depending on the hydroclimatic conditions.
• Gudmundsson, Lukas, Tallaksen, Lena, Wagener, Thorsten, Engeland, Kolbj
  Comparative Diagnostic Evaluation of eight Large Scale Hydrological Models Across Europe
  2011 EGU General Assembly 2011, volume: 13, issue: EGU2011-6364
• Stahl, K., Tallaksen, L.M., Hannaford, J., van Lanen, H.A.J.
  Comparing Trends in European Streamflow Records to Hydrological Change in a Large-scale Hydrological Model Intercomparison Experiment
  2011 American Geophysical Union 2011 Fall Meeting, pages: H43I - 1351
• Jackisch, N., Weiler, M.
  Comparing design assumptions with actual observations for a rain water infiltration system in a residential neighbourhood
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 8532
  » show abstract« hide abstract
  Abstract

  Managing storm water runoff in cities is becoming increasingly complex facing the demand for sustainable solutions of different stakeholders and to adapt to climatic and demographic changes with their high uncertainty. Although the degree of surface sealing is high in cities, there are still natural processes taking place such as infiltration, evapotranspiration and groundwater recharge, though in an altered way. To manage storm water in terms of Best Management Practices, the separated sewer system has been favoured for the last two decades in Germany. Combined with rainwater infiltration systems it is regarded as a good solution to reduce storm runoff in an economical and ecological way with positive effects e.g. improving the micro-climate in cities. To design these systems in a new development, many assumptions are made regarding total amount of generated runoff, concentration times, roughness, infiltration rates, composition of the subsurface, rainfall events etc. Long term data series of precipitation can only be used if models are applied to simulate the designed drainage system. Unfortunately, as in most cases, no data is available to calibrate or verify the model. Despite the shortcomings during the planning and design phase, urban stormwater facilities are rarely evaluated after the construction. With this study we want to provide an example how this gap between design and real functioning could be closed with observations from an experimental urban watershed. The watershed is in a residential neighbourhood in Freiburg built with a separated sewer system from 1997 to 2004. Storm runoff is discharged into vegetated infiltration ditches that are combined with soak-aways due to high ground water levels and low permeable topsoil. For planning, hydraulic-engineering calculations were carried out using a 10-minutes rainfall event with a return period of 10 years extracted from a time series of a nearby weather station. Data from the experimental watershed with observations of water tables in ditches, soak-aways, groundwater wells, precipitation input and the overflow discharge to the nearby stream could now be used to test the design assumptions with the model KOSIM. The comparison between simulations and measurements show the discrepancy between design and the actual processes taking place. Especially the influence of groundwater is often neglected when designing urban stormwater systems but could play an important role for the infiltration of the ditch system. Our study provides a basis for testing hydraulic-engineering models and helps to improve the understanding of hydrological processes in an urban context. A better process conceptualization will improve future management strategies e.g. by considering also the effects of groundwater and infiltration on the quantity and quality of the surface and subsurface water.
• Hannaford, J., Newton, G., Stahl, K., Tallaksen, L.M.
  Decadal-scale river flow variability in Europe: evidence from long hydrometric records spanning 1900 – 2004
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 12053
  » show abstract« hide abstract
  Abstract

  Globally, there is growing concern that anthropogenic climate change is intensifying the hydrological cycle, causing more frequent and severe floods and droughts. There is a growing need, therefore, for observational data with which to discern any emerging trends in river flows, and to compare these with future projections from climate models. However, one of the problems with observed data is that most river flow records in Europe are comparatively short (from the 1960s or 1970s onwards). Recent studies have found significant trends over the last 30 - 40 years in runoff and for a range of indicators of high and low flows, but these records may not give a full picture of long-term change; in particular, trends in short records are heavily influenced by multi-decadal variability driven by atmospheric circulation patterns. This study capitalises on a newly assembled dataset of near-natural daily streamflow records from around Europe (Stahl et al., 2010), consisting of around 400 stations. Whereas Stahl et al. (2010) focused on more recent trends, this study extends the analysis back to the turn of the twentieth century. Around 130 stations have records extending back to the early 1930s; an even longer perspective is provided by the few records which start before 1900. The requirement for long records means the geographical focus is restricted to parts of central and northern Europe. For each of these records, a number of indicators are derived, to enable the assessment of decadal changes in hydrological regimes as well as in extremes. The primary aim of the study is to characterise decadal-scale changes in river flow in Europe, with a particular focus on assessing whether recent decades are representative of historical variability. In the current study, a multi-temporal approach is used to examine changes in river flow indices in moving windows, to assess trends and variability over a range of timescales. Preliminary results suggest that, in some parts of Europe (e.g.in some records from the Nordic countries), patterns of streamflow change have been comparatively stable throughout the twentieth century; in these areas, trends from the last 30 – 40 years are generally representative of changes over longer time periods. However, in other areas (e.g. southern France), there are distinct regime shifts, causing recent decades to contrast notably with other epochs of the last hundred years. There is clearly a need for caution in interpreting the outputs of trend analyses for recent periods, or fixed periods in general. This study provides a first assessment of historical flow variability over long timescales, which can be used as a context for interpreting other trend analyses, and outputs from historical runs of large scale Global Hydrological Models. The multi-temporal approach applied herein could be used in future to examine possible drivers (e.g. large-scale atmospheric circulation patterns) for the decadal patterns of variability presented in this paper. Stahl, K., Hisdal, H., Hannaford, J., Tallaksen, L. M., van Lanen, H. A. J., Sauquet, E., Demuth, S., Fendekova, M., and Jódar, J. 2010. Streamflow trends in Europe: evidence from a dataset of near-natural catchments, Hydrol. Earth Syst. Sci. 14, 2367 – 2382.
• Jackisch, N., Weiler, M.
  Der Einfluss von Grundwasser bei der Regenwasserversickerung in der Siedlungsentwässerung
  2011 Tag der Hydrologie 2011
• Pohl, S., Stoeckl, L., Garvelmann, J., Weiler, M.
  Detailed Spatial and Temporal Observations of Snow Covers in Mountainous Watersheds Using Numerous Low-Cost Standalone Sensors
  2011 EGU General Assembly 2011, pages: EGU2011 - 10273
• Adams, H. D., Luce, C., Breshears, D. D., Weiler, M., Hale, C., Allen, C. D., Smith, A. M., Huxman, T. E.
  Ecohydrological consequences of drought- and infestation-triggered tree die-off: insights and hypotheses
  2011 American Geophysical Union 2011 Fall Meeting, pages: B33B - 0462
• Kuells, C., Weber, R., Dahan, O., Klaus, J., Weiler, M.
  Fast measurement of stable isotope profiles in the unsaturated zone – from equilibrium to flow
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 13447
  » show abstract« hide abstract
  Abstract

  Cavity ringdown spectrometers offer ways to analyze gaseous and liquid water phases in the unsaturated zone. Pioneering work on the comparison of vapour and water profiles in the unsaturated zone (Barnes & Allison, 1988), and on the methodological adaptation to equilibrium laser spectrometry for the saturated zone (Wassenaar et al., 2008) demonstrate the general feasibility of information transfer between vapour and water in the subsurface. A range of laboratory tests were performed in order to ascertain principles of gas water equilibrium fractionation in soils of different textures (sand, silt, loam and clay). Additional field experiments provided data on isotope profiles in different soil types (cambisol, vertisol), textures (silt, loam and clay) as well as in humid (Southern Germany) to semi-arid (Israel) climatic and hydrologic conditions. Results indicate that in principle, laser spectrometry yields relatively fast and high resolution data on isotope distribution of vapour and soil water in the unsaturated zone. Still, laboratory and field procedures need to be established and further developed in order to assure that isotope ratios can be reproduced and inter-compared. The calibration of results and comparison to mass-spectrometry standards revealed no significant bias for sand and silt and a weak but significant bias from standard equilibration fractionation in clays. Some general patterns apparent in the measurement of stable isotopes in soil water by laser spectrometry raise further research questions about the balance between equilibrium and flow processes in the unsaturated zone.
• Weiler, M., Steinbrich, A.
  How can a non-calibrated, distributed rainfall-runoff model help balance between model uncertainty and model complexity?
  2011 American Geophysical Union 2011 Fall Meeting, pages: H31N - 06
• Brena, A., Stahl, K., Weiler, M.
  How does forest disturbance and succession affect summer streamflow recession?
  2011 American Geophysical Union 2011 Fall Meeting, pages: H23K - 01
• Grodek, T., Lange, J., Lekach, J., Husary, S.
  Limited runoff response in Mountainous Middle Eastern cities
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 6366
  » show abstract« hide abstract
  Abstract

  The Mediterranean climate together with the type of urban setting found in mountainous Middle Eastern cities generate much lower runoff yields than previously reported and than usually estimated for urban design. In fact, a close analysis shows that most of the rainwater remains within the cities as a possible source for urban groundwater recharge. The present study examined two locales – Ramallah, an old traditional Palestinian Arab town, and Modiin, a new township in Israel – both situated on the karstic Yarkon Taninim aquifer. This aquifer supplies the only high-quality drinking water in the region (one quarter of the Israeli-Palestinian water demand), which is characterized by dense populations and limited water resources. This paper provides the first measured information on the hydrological effects of urbanization in the area. It was found that the shift of the mountainous natural steep slopes into a series of closed-terraced homes and gardens created areas that are disconnected from the urban runoff response. Roofs drained into the attached gardens and created favorable recharge units. Mainly low-gradient roads became the principal source for urban runoff already following 1-4 mm of rainfall. Parallel roads converted single peak hydrographs towards multi-peak runoff responses, increasing flow duration and reducing peak discharges. The remaining urban area (public parks, natural areas, etc.) generated runoff only as a result of high-magnitude rainstorms. All of the above conditions limited urban runoff coefficients to an upper boundary of only 35%. During extreme rainstorms (>100mm) similar runoff coefficients were measured in urban and natural catchments as a result of the limited areas contributing to runoff in the urban areas, while natural terrain does not have these artificial limits. Hence, it was found, the effects of urbanization decrease with event magnitude and there is significant potential for urban groundwater recharge. However, frequent low-magnitude rainstorms often generate highly polluted stormwater in urban sewer systems and this water should only be used with great caution. This long-term monitoring study was funded by the German Science Foundation in the framework of a trilateral German-Palestinian-Israeli science support program, and GLOWA – Jordan River Project, funded by the German Ministry of Science and Education in collaboration with the Israeli Ministry of Science and Technology.
• Gudmundsson, L., Tallaksen, L.M., Stahl, K., Fleig, K.
  Low-frequency runoff dynamics: catchment vs climate controls
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 6780-2
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  Abstract

  Catchment runoff depends on atmospheric water input (precipitation) and loss (evapotranspiration) as well as on catchment processes, which determine how atmospheric fluctuations are translated into runoff. On short time scales (days, months) a multitude of processes is known to influence runoff generation. On longer time scales (years, decades) climate fluctuations gain increasing importance. To assess the different roles of catchment-processes and climatic forcing on time scales longer than 12 months and thus elucidate catchments’ sensitivity to climate change, this study considered the variance and the temporal evolution of the low-frequency components of runoff. The analysis was based on 375 monthly series of observed pan-European runoff (small near-natural catchments) and corresponding time series of precipitation and temperature from a bias-corrected re-analysis product (the WATCH forcing data). The dominant space-time patterns of the low-frequency components of runoff, identified using isometric feature mapping (isomap), were found to be closely related to the space-time patterns of low-frequency precipitation and temperature components. The fraction of low-frequency variance of runoff is on average larger than (and not correlated to) the fraction of low-frequency variance of precipitation and temperature. However, it is correlated with water balance characteristics such as mean annual runoff, precipitation, and temperature, indicating that they control the amplification of climatic fluctuations. More precisely, the fraction of low-frequency variance of runoff increases (decreases) under dryer (wetter) conditions. These findings may be of particular interest for climate sensitivity studies. The influence of a given climate signal on runoff may vary largely between streams, depending on the long-term water budget. Climatic change, however, may influence the mean water budget, eventually changing the fraction of low-frequency variance of runoff. In the case of increasingly wetter conditions, low-frequency runoff variability is likely to decline, simplifying water management on a year to year basis. On the other hand, increasingly drier conditions may lead to an increase in the low-frequency runoff variability, eventually decreasing predictability and challenging water management.
• Hartmann, A., Lange, J., Weiler, M., Arbel, Y., Greenbaum, N.
  Modeling the variability of karstic recharge - a multi-objective approach
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 911
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  Abstract

  Many parts in the Mediterranean are karst regions, where groundwater balances the annual variability of water availability. In these regions recharge is controlled by the epikarst. Located at the upper parts of the carbonate rock, it acts as temporary storage and distribution system for infiltrating water into the karst system. Depending on precipitation, system state and location, diffuse as well as concentrated percolation, enhanced by lateral flow towards enlarged fissures, can occur. This results in a high spatial and temporal variability of karstic recharge. To adequately represent the dominating recharge processes in hydrological models is still a challenge, especially in data scare regions. In this study we have developed a conceptual, process-based model implementing the variability of karstic recharge. We hypothesize that the shape of the lower epikarst boundary to the rock matrix controls the abundance and quantity of lateral flow and hence concentrated infiltration. Introducing a power law function describing the boundary’s shape we define model compartments with varying depth. Reaching the semi-permeable lower boundary infiltrating water can create a perched water table and flow laterally towards neighboring compartments following the hydraulic gradient. This procedure results in a spatial pattern of percolation rates (one for each compartment), which sum up to a net percolation for a considered area. Hence, not only an average percolation rate but also information about its variability is simulated. The model was benchmarked with measured responses of a set of drips (stalactites) in a karstic cave at Mount Carmel, Northern Israel, which is located 28 m below surface. These data comprise both dripping rates and the concentration of selected tracers (EC, chloride, bromide). For model calibration we did not fit single hydrographs but statistical parameters of the average response function for all measured drips (mean, standard deviation, skewness). The model was applied to two different time scales. First, we simulated a two-day sprinkling experiment yielding high resolution data for dry and wet preconditions. Second, we applied the model to an entire season under natural conditions. Model performance and parameter values were analyzed and general recommendations for its use to simulate karst recharge were derived.
• Stahl, K., Tallaksen, L.M., Hannaford, J., van Lanen, H.A.J.
  Observed runoff trends across Europe - a benchmark for land surface and global hydrological model simulations
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 11375
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  Abstract

  Runoff from river basins in Europe has been found to exhibit trends over the twentieth century that have some parallels with climatic changes, i.e. to warmer winters in the north, a stronger seasonality in central Europe and overall drier conditions in the south. Such changes can provide a benchmark, against which the performance of models that are used to project future hydrological change can be evaluated.Within the EUWATCH project, several land surface and global hydrological models have taken part in a model intercomparison project (WaterMIP) to compare global water balance simulations in a consistent way. Eight of the models were run for a longer time period (1964-2001) using the same climate database, i.e. the bias-corrected WATCH Forcing Data. These simulations were used in this study to investigate how modelled runoff trends compare to trends in observations from over 400 small basins with near-natural flow conditions, drawn from across Europe. While the main aim was to test trends as a benchmark, the comparison across models (having different model structure and parameterization) can also assist attribution of trends and elucidate which process descriptions models may need to improve. The results show that overall regional patterns of trends in annual runoff are well reproduced, which suggests that the quality of the common forcing data is satisfactory. However, trends in monthly runoff and trends in extremes are not well represented and differ substantially among the models.WaterMIP has already described the major differences among the models, such as in the simulation of snow accumulation and melt. We show that these differences can have a transient effect, i.e. they cause differences in the long-term trends of seasonal runoff and hydrological extremes. Consequently, the sensitivity of streamflow to climate variability in a particular region may be difficult to judge for some of the models. In this presentation such model-specific differences are demonstrated and it is further illustrated how validating models for trends or long-term variability can reduce uncertainty in the interpretation of model projections of the hydrological response to climate change.
• Brena, A., Weiler, M., Stahl, K.
  Predicting evapotranspiration change in a successionnal forest without eddy covariance measurements
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 8759
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  Abstract

  In the lifetime of terrestrial ecosystems disturbance events are a normal, reoccurring process. In forested ecosystems, landscape succession can result in long-lasting changes of the hydrological behavior, in particular changes in evapotranspiration. Evapotranspiration models used in hydrology, however, commonly assume a homogeneous forest age. Experimental data from eddy covariance measurements are scarce and rarely monitor forest successions. Therefore there is a need for alternative methods to understand differences in AET in differently aged forests and improve AET estimates in developing landscapes. In this study we developed a minimalist conceptual model to predict actual evapotranspiration (AET) during summer from soil water depletion data. The approach was applied to three experimental sites in Western Canada which represent a forest succession (different stand ages in a similar environment). The objective was to gain insights into the role of forest stand age, interannual climate variability, and the Horton index (rate of vaporization to wetting) in controlling summer AET. We used continuous soil moisture and precipitation data over 20 years to drive the model at different temporal resolutions. The results were compared with observed AET measurements (eddy-covariance data). The results show that easy-to-measure soil water depletion can be used to make predictions of summer AET for half-hourly and daily time scales. The approach could predict the differences from 5 to 35% of AET among the differently aged stands. The results are sensitive to the canopy architecture, active root depth and stand age. Moreover, we find that the model is reliable despite summer dry-wet transitions due to sporadic rainfall events. Finally, the interannual variability of the Horton index at each stand implies different root water uptake strategies during landscape succession. If the model should prove successful for a wider range of forest landscapes, envisioned applications include estimates at sites where eddy covariance data are inexistent or impossible (e.g. complex terrain) or for large-scale water balance assessments using remote-sensing techniques.
• Gudmundsson, L., Tallaksen, L.M., Stahl, K.
  Projected changes in future runoff variance - a time scale dependent analysis
  2011 American Geophysical Union 2011 Fall Meeting, pages: GC51D - 1008
• Kuells, C.
  Resilience of urban water supply systems to natural hazards and systemic risks
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 12627
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  Abstract

  Urban agglomerations exhibiting rapid population growth require a commensurate development of water supply, sanitation and water treatment infrastructure. The adjustment of infrastructure is especially difficult and not always strategically planned in peri-urban areas of large cities in developing countries and emerging economies. Standards for water supply and sanitation and guidelines for the sustainability of water supply help managing such adaptation processes. Still, sufficiency and sustainability seem to be necessary but insufficient principles for the development, adaptation and management of water supply systems: The resilience or robustness of urban water supply in the event of natural hazards appears to be a necessary additional principle. A review indicates that there is a need for quantitative or at least nominal scales of resilience and for viable operational concepts of its characterization. A comparison of water supply concepts in rapidly growing urban centres (Windhoek/Namibia, Fortaleza/Brazil, Capetown/South Africa) indicates that there are large discrepancies between the associated risks of failure in the advent of meteo-hydrological hazards (floods, droughts, heat waves) or other factors (pollution, algae bloom). Some systems also seem to become less stable by an increase of systemic risks, especially related to feedbacks between water quantity, water quality and socio-economic responses. Innovative concepts such as the integration of surface and groundwater supply, water re-use and managed aquifer recharge that undoubtedly have positive impacts on overall sustainability, may still lead to an increase of systemic risks of infrastructure failure. Based on the discussion of case studies, and on examples of system failure and recovery given, a framework for the characterization and management of resilience of urban water supply to natural hazard is proposed.
• Külls, C.
  Resilience of urban water supply systems to natural hazards and systemic risks
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 12627
• Tallaksen, L.M., Stahl, K.
  Spatial and Temporal Drought Characteristics in Europe from a Multi-Model Ensemble of Simulated Runoff
  2011 American Geophysical Union 2011 Fall Meeting, pages: H43H - 1331
• Weiler, M., Bachmair, S.
  Subsurface Flow and Runoff Response at the Hillslope Scale: Spatio-Temporal Thresholds and Vegetation Cover Effects
  2011 American Geophysical Union 2011 Fall Meeting, pages: H44F - 04
• Schuetz, T., Weiler, M., Lange, J.
  The effect of emerging wetland vegetation on solute transport processes
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 8706
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  Abstract

  The occurrence of aquatic vegetation in shallow, slow flowing systems such as wetlands, estuaries or shallow rivers strongly influences solute transport processes. Vegetation communities or even single plants may affect hydraulic characteristics of wetland systems through the appearance of preferential flow paths and physico-chemical retention processes (e.g. sorption, microbial degradation, light decay). We studied the impact of emerging wetland vegetation (Phragmitis Australis, Thypha Latifolia and Juncus Conglomeratus) and sediment accumulation on the changes of conservative and non-conservative solute transport processes.We carried out four different multi-tracer experiments in March and August 2010 in a 258 m2 constructed free water surface wetland in south-western Germany. Tracer breakthrough curves resulting from two different tracer injection methods (slug injection and constant rate injection) characterize the properties of the wetland in early spring (with initial vegetation of one plant per m2) and in summer (with dense vegetation cover and additional sediments). Solute transport was simulated by the transient storage model OTIS and compared to the different breakthrough curves. The conservative tracer bromide was used to quantify the 30% decrease of wetland volume (spring to summer) and the change of preferential flow areas relative to storage zones and their exchange rate. While the relative mean residence time decreased on average by 10 % (increase of preferential flow paths), the relative fraction of storage zones increased from 42% in spring to 61% in summer. Then, the calibrated OTIS was modified to include sorption processes and light decay. As such, the sorptive, but light insensitive fluorescent dye Sulphorhodamine B and the slightly sorptive, but photo-degradable dye Uranin could be simulated. Sorption (linear isotherm, reversible) was found to be higher if vegetation density increases. Light decay was on average 50 times higher in non-shaded flow channels. Finally, we validated this approach by predicting the transport of the sorptive and photo-degradable dye Eosin. The closed boundaries of the wetland system (underlying clay layer, defined input and output) allowed us to use an integrative multi-tracer experiment and 1-D modelling approach to quantify the overall characteristics and effects of the emerging vegetation in wetlands and their implication for conservative and non-conservative solute transport. This study was performed within the framework of the EU-Life-Project ArtWET (06 ENV/F/000133).
• Gimbel, K., Kuells, C., Weiler, M.
  The role of plants in site and catchment isotope response
  2011 EGU General Assembly 2011, volume: 13, pages: EGU2011 - 13539-1
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  Abstract

  The role of plants in isotope hydrology is investigated based on a literature review covering hydrological, botanical and plant phyiological journals. A wealth of studies on isotope effects by plants exists evidencing a range of processes through which plants alter the stable isotope composition not only of cell water but also of soil and groundwater. A new general classification scheme of isotope effects is proposed that summarizes well documented isotope effects from the canopy, through plant and cell water exchange down to root zone effects such as redistribution. A research gap between the observation of isotope effects at the plant scale and a translation into site to catchment response was found. Therefore, a simple general plant isotope effect model is proposed that translates isotope effects into response for different climate, soil and site conditions.

2010

• Steinbrich, Andreas, Weiler, Markus
  A non-calibrated, runoff process-based rainfall-runoff model for prediction of floods in ungauged basins
  2010 EGU General Assembly 2010, volume: Geophysical Research Abstracts 12, EGU2010-6668
• Bachmair, S., Weiler, M.
  A novel technique to measure subsurface flow velocity
  2010 American Geophysical Union 2010 Fall Meeting, pages: H11A - 0787
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  Abstract

  To better understand subsurface flow (SSF) processes at the hillslope scale, measuring subsurface flow velocity should be of great interest. However, due to the large heterogeneity in time and space, we are faced with the need to continuously measure SSF velocity at several locations within a hillslope over a distance being representative for certain hillslope segments. At present, SSF velocity is either measured by tracer tests over larger distances or via centimeter-scale measurements using heat dissipation or other tracers. This calls for a cheap and easily applicable method to continuously detect subsurface flow velocity in the field over a distance representative for certain hillslope segments. We currently develop a novel technique, which has shown promising results in the laboratory. The technique is based on an automatic salt tracer injection into a small-diameter borehole once the soil matrix has reached saturation. The tracer signal is captured by a 5TE probe (Decagon Devices) measuring soil moisture, electrical conductivity, and temperature every two minutes, which is inserted a few decimetres downslope of the injection point into the soil. The automatic injection is also controlled by the 5TE probe, which is connected to a CR1000 Logger (Campbell Scientific). Once saturated conditions have been established, a plug valve attached to an above-mounted bottle with NaCl solution is opened for 2 seconds and the tracer is injected into the borehole via a small steel tube screened at the bottom. Under saturated conditions the automatic injection is conducted every two hours and the breakthrough curves are analyzed for the mean effective velocity. In a first step, the technique was tested in a sand filled box with constant in- and outflow conditions representing a homogeneous miniature hillslope. Several experimental set-ups differing in hydraulic gradient, distance from injection point to 5TE probe, orientation of 5TE probe, and amount and concentration of tracer injection were tested. After the successful application in the laboratory the instrument was recently installed in the field and is now being tested under field conditions.
• Andreas Steinbrich, Markus Weiler
  Ausweisung der für die Hochwasserentstehung wichtigen Abflussbildungsprozesse für Baden-Württemberg
  2010 Niederschlag-Abfluss-Workshop
• Schuetz, T., Lange, J., Weiler, M.
  Characterization of solute transport properties of different types of constructed wetlands using multi-tracer data and transient storage modelling
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 967
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  Abstract

  Constructed wetlands in agricultural headwater catchments may serve as simple treatment systems to improve retention and mitigation of agricultural non-point-source pollution. To calculate and predict retention capacities of 6 different constructed wetland systems concerning micro-pollutants, we used a one-dimensional solute transport model to compare the results of a series of multi-tracer experiments. The investigated wetland systems consisted of two surface flow wetlands with permanent through flow, two vegetated ditches, a forest buffer zone and a flood detention pond. Transport behaviour was investigated using different tracers: salt and two differently sorptive fluorescent dyes (Sulphorhodamine B and fluoresceine). The hypothesis that shallow and vegetated systems offer the highest sorption capacity for sorptive but mobile pollutants was tested applying a solute transport model to the observed tracer breakthrough. The transport model OTIS (Runkel, 1998) which includes advection, dispersion and lateral exchange to a transient storage was optimized to observed breakthrough of applied tracers at defined cross-sections along the wetlands. Optimized model parameters include dispersivity, cross-sectional areas of both stream and transient storage, as well as an exchange coefficient. Sorption was included based on the KD value, mass of accessible sediment and a sorption coefficient. We assumed that each measurable cross-section is a combination of dead zones and flowing parts. For three of the wetland systems we could exclude lateral in- and outflows. For the other systems, a quantification of lateral flows was possible. We used the set of conservative tracer data to calculate conservative transport characteristics and cross-sections. Then we applied the calibrated model on the sorptive tracer data only using sorption capacity in the storage zone as a calibration parameter and observed KD values and mass of accessible sediment. The results for the different tracer experiments show that the chosen model is capable of reproducing the observed breakthrough of conservative and non-conservative tracers in a satisfactorily manner. As expected, shallow and vegetated systems offer the highest sorption capacity for sorptive pollutants. The approach can be used to predict solute transport within wetland systems and to design the optimal flow length for a specific wetland system, which may serve as a retention measure to mitigate agricultural non-point source pollution.
• Schuetz, T., Weiler, M.
  Detection and quantification of localized groundwater inflow in small streams using ground-based infrared thermography
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 964-1
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  Abstract

  Localized groundwater (GW) inflow into small streams can be a major source of runoff during low flow periods in headwater catchments. The localization and determination of the fraction of runoff corresponding to a certain area may give insights into aquifer type, flow processes, the composition of base-flow concerning the spatial distribution of catchment storage and water quality issues. Though GW temperature has a small amplitude during the year compared to surface water, a significant temperature difference between stream water and groundwater can be expected in summer and winter. As the technical development of infrared thermography is progressing (the spatial resolution of infrared camera systems is increasing and the measuring error is decreasing) we tested ground based infrared thermography as a non-invasive and remote applicable method to detect and quantify GW entries in small streams during baseflow periods (<10 l/s). This method offers the possibility to determine the exact location of inflow and the reach length that is needed for complete mixing of stream and ground waters. Several experiments were conducted in two headwater catchments in southern Germany with flow varying between 0.5 l/s in summer and 3 l/s in winter. The locations of GW entering the stream and the flow lengths of complete mixing were detected using a handheld thermographic system (INFRATEC). In addition, water temperature and electric conductivity of the groundwater entering the stream and of the stream water up- and downstream of localized GW inflow were measured with temperature and EC sensors. Though the zones of complete mixing were identified, point measurements and surface radiation temperatures were taken from the same areas. Discharge measurements were conducted using the salt dilution method with continuous injection. End-member mixing calculations were done using the measured EC and water temperature data and compared to the results of mixing calculations of observed water surface radiation temperatures. The discharge observations were used to validate the fraction calculations. Calculated GW entries using thermogramms had comparable deviations from the measured runoff fractions to those from direct temperature and EC measurements. This leads to the conclusion that the use of ground-based infrared thermography for the detection and quantification of localized groundwater inflows into small streams is a valuable and easy applicable tool for field hydrology.
• Kuells, C., Ritter, M.
  Deuterium excess anomaly of precipitation in Svalbard
  2010 American Geophysical Union 2010 Fall Meeting, pages: A51E - 0179
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  Abstract

  The isotopic composition of precipitation and melt-water lakes in Svalbard was studied. The IAEA precipitation record of monthly precipitation data from Ny Alesund reveals a much stronger and regular seasonal variability of deuterium excess compared to oxygen-18 and deuterium. The seasonal amplitude of deuterium excess in Ny Alesund is more pronounced than in stations of similar latitude in Greenland and Iceland. Ratios of 18O/16O and 2H/H vary between single events and do not show a clear seasonal pattern. These principle observations have been applied to the investigation of melt-water lakes in Svalbard using the stable isotopes of water. For each melt-water lake samples have been taken of the uppermost layer of the surrounding snow pack, of melt-water inflow(s), the lake water itself and the existing outflow. Samples have been analyzed for 18O/16O and 2H/H with laser ring-down spectrometry. Based on observed topological and geomorphometric data the mean residence time was estimated indicating turnover within days to few weeks. Kinetic isotope fractionation by evaporation was observed only in the inflow of the lowest lake. The isotopic data from melt-water lakes reflects the deuterium excess anomaly observed in the precipitation data from Svalbard. The hydrological input to the melt-water lakes from snow-melt and groundwater could be identified. While the hydrological regime of most lakes is dominated by melt-water, significant groundwater inflow could be detected in specific lakes. In this environment the investigation of hydrological processes and properties of hydrological systems can be improved by using the information content of deuterium excess seasonality. Deuterium excess results from ocean-atmosphere interactions and reflects moisture conditions and temperature gradients during evaporation in the source region of atmospheric moisture. In high-latitude environments deuterium excess seasonality and variability contains information about changes in circulation patterns that can be traced through hydrological systems.
• Gunkel, A., Lange, J.
  Distributed modelling of water resources in the Lower Jordan River Basin - from present day variability to suitability for new water sources
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 1004
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  Abstract

  The Middle East is characterized by a high temporal and spatial variability of rainfall. As a result, water resources are not reliable and severe drought events are frequent, worsening the natural water scarcity. Single high magnitude events may dominate the water balance of entire seasons – a fact that is poorly represented in the assessments of available water resources that are normally based on long term averages. Therefore, a distributed hydrological model with a high temporal and spatial resolution is applied to the Lower Jordan River basin (LJRB). The focus is hereby to capture the variability of rainfall and to investigate how this signal is amplified in the hydrological cycle in this arid and semi arid environment. Rainfall variability is addressed through a volume scanning rainfall radar providing precipitation data with a resolution of 5 minutes for entire seasons that serves as input to a conceptual hydrological model. The raw radar data recorded by a C-Band system was pre-corrected by a multiple regression approach prior to regionalization to the LJRB, ground truthing with rainfall station data and conditional merging. Despite certain uncertainties, the data documents the accentuated rainfall variability in the entire LJRB. In order to include the full range of present rainfall variability, one average and two extreme seasons (wet and dry) are studied. Hydrological modelling is undertaken with a new modelling tool created by coupling two hydrological models, TRAIN and ZIN, complementing each other in respect to the addressed processes and water fluxes. The resulting modelling tool enables conceptual modelling of the processes relevant for semi-arid / arid environments with a high temporal and spatial resolution. The model is applied to the large scale LJRB (16,000 km2) in order to simulate all components of the water balance for three rainy seasons representing the present climate variability. Under given conditions of low data availability, the results give a basin wide view on the availability of surface water resources without human intervention with a high resolution in time (5 min) and space (up to 250 x 250 m2). The scarcity of water resources in many areas within the region is illustrated and detailed maps of the water balance components reveal spatial pattern of water availability characterizing the different potentials of regions or sub basins for water management options. Moreover, comparing different climate conditions provides valuable information for water management, including insights into the relation between green and blue water. For instance, runoff generation and percolation react stronger to changes in precipitation than evapotranspiration and the changes in runoff and percolation are considerably higher than the differences in rainfall between the three years. This amplification of rainfall variability by the hydrological cycle is significant for water management. Based on the results for current conditions, the impact of different scenarios and management options is analyzed, e.g. the effect of land use changes or the suitability of different regions for rainwater harvesting, one of the urgently needed new water sources.
• Lange, J., Passeport, E.,, Tournebize, J.
  Fluorescence tracers as a reference for pesticide transport in wetland systems
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 6668
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  Abstract

  Two different fluorescent tracers, Uranine (UR) and Sulforhodamine (SRB), were injected as a pulse into surface flow wetlands. Tracer breakthrough curves were used to document hydraulic efficiencies, peak attenuation and retention capacities of completely different wetland systems. The tracers were used as a reference to mimic photolytic decay (UR) and sorption (SRB) of contaminants, since a real herbicide (Isoproturon, IPU) was injected in parallel to UR and SRB. Analysis costs limited IPU sampling frequency and single samples deviated from the tracer breakthrough curves. Still, a parallel behavior of IPU and SRB could be observed in totally different wetland systems, including underground passage through drainage lines. Similar recovery rates for IPU and SRB confirmed this observation. Hence, SRB was found to be an appropriate reference tracer to mimic the behavior of mobile pesticides (low KOC, without degradation) in wetland systems and the obtained wetland characteristics for SRB may serve as an indication for contaminant retention. Owing to the properties of IPU, the obtained results should be treated as worst case scenarios for highly mobile pesticides. A comparison of six different wetland types suggested that non-steady wetland systems with large variation in water level may temporally store relatively large amounts of tracers (contaminants), partly in areas that are not continuously saturated. This may lead to an efficient attenuation of peak concentrations. However, when large parts of these systems are flushed by natural storm events, tracers (contaminants) may be re-mobilized. In steady systems vegetation density and water depth were found to be the most important factors for tracer/contaminant retention. Illustrated by SRB, sorption on sediments and vegetation was a quick, almost instantaneous process which lead to considerable tracer losses even at high flow velocities and short contact times. Shallow systems with dense vegetation appeared to be the most efficient SRB/contaminant traps. For photolytic decay no reference contaminant was studied, but the results found for UR may serve as a valuable proxy for this process.
• Weiler, M., Lange, J.
  How can a modular Master Program in Hydrology provide a framework for future education challenges?
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 13317
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  Abstract

  A new Master program in Hydrology started at the University of Freiburg in 2008 as a continuation of the Diploma program in Hydrology due to the proposed changes according to the Bologna ac-cord. This imposed formation provided a perfect opportunity to develop a new program that is able to meet the challenges of future hydrology students to work in a nonstationary world due to climate and land use change. A modular program with individual three week hydrological courses was es-tablished, which builds on a general bachelor knowledge in natural sciences. Besides broad theory, students are taught in all relevant methods of hydrological field data collection and laboratory analy-sis. Recurrently, practical data analysis is carried out using freeware software tools. Examples in-clude time series analysis, (geo-)statistics and independently programmed water balance models including uncertainty assessments. Students work on data sets of different climatic zones and are made aware of hydrological problem areas around the globe. Hence, graduates know how to collect, analyse and evaluate hydrological information and may prepare their own, independent tools to pre-dict future changes. In addition, the new modular program includes instructors from the industry and public authorities to provide the students a broad perspective of their future profession. Finally, the new program allows directly to teach university students and practicing hydrologists together to provide evolving methods in hydrology to the practitioners and to allow contacts to professional for the university students.
• Brena, A., Weiler, M., Stahl, K.
  Inferring long-term water balance dynamics in forested watersheds: Tracing vegetation cover transitions
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 564
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  Abstract

  The dynamics of catchment water balance remains a challenging question in hydrology especially within an environmental change context. While the temporal variability of catchment response to internal -land use- and external -climate- forcings is important for human and environmental needs, understanding the spatial variability of this response is relevant for prediction and regionalization. Among the water balance components evapotranspiration (AET) is the most difficult to measure and estimate but it is also the component that varies highly with climate and land surface conditions. Therefore, new approaches are needed that allow the attribution of variability and changes in AET through exploration of observed hydroclimatic records in watersheds. Due to an unprecedented large-scale tree epidemic, significant land use changes in natural watersheds are currently occurring in British Columbia, Canada. The aim of this work is to study the role of long-term land use history, i.e. forest harvesting or dying and subsequent regrowth, in the long-term water balance variability in forest watersheds of this region. We first test the transferability of an ecohydrological curve suggested by Krestovsky (1980) and Kuczera (1987) that describes the landscape response of AET following forest regrowth after clear-cutting. During this recovery period a “peak” reference AET is reached approximately 60 years after the forest disturbance occurred followed by another 60 years to reach constant AET. We assume that these changes in AET will directly impact the streamflow response and apply this curve to watersheds with different patterns of forest age. We studied 8 watersheds with different size, topography, hydroclimatology and land cover history located throughout the Pacific Northwest. Since the historical land use is different in every watershed, results show a different trend and magnitude of observed and simulated actual evapotranspiration. For the 2 paired watersheds the observed and predicted streamflow changes are well reconstructed using the proposed ecohydrological curve. For the unpaired watersheds significant correlations between the simulated long-term changes in AET and simple estimates of evaporation using the catchment water balance approach (E=P-Q) were found. These correlations seem to be stronger when comparing the results to the Q/P and E/P ratios. The observed variability in the water balance in some Pacific Northwest watersheds can be explained to some extent by the forest ecophysiology at the catchment scale. Nevertheless, accurate forest disturbance data is critical to investigating water balance dynamics.
• Gudmundsson, L., Tallaksen, L.M., Stahl, K.
  Large-scale patterns of wetness and drought of European streamflow on inter-annual to decadal time scales
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 9596
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  Abstract

  Large scale fluctuations of streamflow are of interest to a wider community. Once identified, they can be directly compared to the corresponding fluctuations of climatic variables and they offer a benchmark for large scale hydrological models. We present a hydroclimatology of Europe, based on a large pan-European data set comprising more than 500 monthly streamflow series covering the period 1962 to 2004. The time series under investigation are low passed filtered by means of Singular System Analysis such that only inter-annual variability is maintained. The relation between the corresponding low frequency components is quantified by means of rotated Principal Component Analysis. Significant components are chosen based on an objective bootstrapping criterion. The identified patterns correspond to regions of high temporal coherence. The corresponding temporal structures are further analyzed with respect to drought and wetness trends as well as their dynamical coupling to patterns of published precipitation anomalies.
• Spiegelhalter, K., Stahl, K.
  Modelling the coupled influence of climate and glacier change on discharge
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 10895-1
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  Abstract

  Localized groundwater (GW) inflow into small streams can be a major source of runoff during low flow periods in headwater catchments. The localization and determination of the fraction of runoff corresponding to a certain area may give insights into aquifer type, flow processes, the composition of base-flow concerning the spatial distribution of catchment storage and water quality issues. Though GW temperature has a small amplitude during the year compared to surface water, a significant temperature difference between stream water and groundwater can be expected in summer and winter. As the technical development of infrared thermography is progressing (the spatial resolution of infrared camera systems is increasing and the measuring error is decreasing) we tested ground based infrared thermography as a non-invasive and remote applicable method to detect and quantify GW entries in small streams during baseflow periods (<10 l/s). This method offers the possibility to determine the exact location of inflow and the reach length that is needed for complete mixing of stream and ground waters. Several experiments were conducted in two headwater catchments in southern Germany with flow varying between 0.5 l/s in summer and 3 l/s in winter. The locations of GW entering the stream and the flow lengths of complete mixing were detected using a handheld thermographic system (INFRATEC). In addition, water temperature and electric conductivity of the groundwater entering the stream and of the stream water up- and downstream of localized GW inflow were measured with temperature and EC sensors. Though the zones of complete mixing were identified, point measurements and surface radiation temperatures were taken from the same areas. Discharge measurements were conducted using the salt dilution method with continuous injection. End-member mixing calculations were done using the measured EC and water temperature data and compared to the results of mixing calculations of observed water surface radiation temperatures. The discharge observations were used to validate the fraction calculations. Calculated GW entries using thermogramms had comparable deviations from the measured runoff fractions to those from direct temperature and EC measurements. This leads to the conclusion that the use of ground-based infrared thermography for the detection and quantification of localized groundwater inflows into small streams is a valuable and easy applicable tool for field hydrology.
• Weiler, M., Gimbel, K., Weber, R.
  Only one isotopic water world: relevant processes at the soil-vegetation-atmosphere interface
  2010 American Geophysical Union 2010 Fall Meeting, pages: H54B - 03
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  Abstract

  The stable water isotopes of oxygen and hydrogen have been used to gain process and system knowledge about flow pathways, residence times, mixing and redistribution for many decades. In recent years the processes due to water-ecosystem interactions have become more relevant and new ideas how processes effect the isotopic signature of soil water and runoff have been postulated (e.g. Brooks et al, 2009, doi:10.1038/NGEO722). On the other side, new measurement techniques have increased the sampling rate of stable water isotopes in soils and plants tremendously. This allows us, for example, to measure stable isotope profiles in soils up to several meters in depth with sub-decimetre sampling interval within 2 days. Using these rich datasets together with physically-based modelling of water and isotope fluxes in soils and plants we investigated distinct processes at the soil-vegetation-atmosphere interface that influence the isotopic signature in soil water, recharge and runoff. We hypothesize that a combination of distinct processes in combination with the local climate can considerably alter the isotopic signature of streamwater or groundwater and that these processes are often not adequately considered. A literature survey revealed eight mechanisms, which can be grouped into redistribution, selection, leakage and uptake effects that have the potential to modify the isotopic signal in runoff or recharge. Applying the proposed modelling concepts to a variety of climate and vegetation conditions we can predict the impact of individual and multiple effects on the isotopic signature in runoff as well as on the isotope profiles in soils. The predicted profiles match well with the observed profiles. This framework allows us finally to predict if the isotopic signature is significantly altered under specific soil-vegetation-atmosphere conditions..
• Stahl, K., Tallaksen, L.M., Gudmundsson, L.
  Performance benchmarking of large-scale models with observations from unregulated streamflow records across Europe
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 10594
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  Abstract

  High-resolution regional climate models and coupled or off-line land surface models routinely provide the basis to study regional patterns of future changes in large-scale hydrology. Hence there is a great need for the validation of simulated characteristics of spatial and temporal runoff dynamics with independent observations. Employing a pan-European data set of over 400 records of unregulated streamflow assembled from the updated EuropeanWater Archive and various national agencies provides an opportunity for such an analysis and allows testing the limits of interpretability of spatial and temporal runoff dynamics from large-scale models. The observed records were compared to a high-resolution European re-analysis as well as other land surface model experiments performed for the EU-WATCH project for the time period 1964-2002. For this purpose we first transformed all daily records into their daily percentile series to obtain series of non-parametric anomalies. The agreement between modelled and observed anomalies was investigated by means of correlation analysis as well as by analyzing spatio-temporal patterns of the error field by means of principal component analysis. The general patterns at the European scale were found to agree well. However, the results also allow a more detailed analysis of differences that are particularly pronounced during drought periods. Identifying regions as well as time periods where and when these differences are significant will assist evaluating the reliability of predictions of hydrological change at different scales and suggest specific modifications in model concepts.
• Staudinger, M. , Stahl, K., Tallaksen, L.M., Clark, M.P., Seibert, J.
  Performance comparison of hydrological model structures during low flows
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 8263-2
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  Abstract

  Low flows are still poorly reproduced by common hydrological models since they are traditionally designed to meet peak flow situations best possible. As low flow becomes increasingly important to several target areas there is a need to improve available models. We present a study that assesses the impact of model structure on low flow simulations. This is done using the Framework for Understanding Structural Errors (FUSE), which identifies the set of (subjective) decisions made when building a hydrological model, and provides multiple options for each modeling decision. 79 models were built using the FUSE framework, and applied to simulate stream flows in the Narsjø catchment in Norway (119 km2). To allow comparison all new models were calibrated using an automatic optimization method. Low flow and recession analysis of the new models enables us to evaluate model performance focusing on different aspects by using various objective functions. Additionally, model structures responsible for poor performance, and hence unsuitable, can be detected. We focused on elucidating model performance during summer (August - October) and winter low flows which evolve from entirely different hydrological processes in the Narsjø catchment. Summer low flows develop out of a lack of precipitation while winter low flows are due to water storage in ice and snow. The results showed that simulations of summer low flows were throughout poorer than simulations of winter low flows when evaluating with an objective function focusing on low flows; here, the model structure influencing winter low flow simulations is the lower layer architecture. Different model structures were found to influence model performance during the summer season. The choice of other objective functions has the potential to affect such an evaluation. These findings call for the use of different model structures tailored to particular needs.
• Jackisch, N., Weiler, M.
  Rainwater infiltration in urban areas and implications for groundwater quality
  2010 GQ10 Groundwater Quality 2010
• Davila, P., Kuells, C.
  Reliability of current CFC data for age dating of water
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 536
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  Abstract

  Age dating of water based on dissolved CFCs and Krypton-85 has been applied extensively for many years. CFCs were adopted as an approach for water dating due to the availability of global input functions and because of a straightforward methodology. In the last decade, due to international treaties, CFCs production and atmospheric concentrations of some trace gases (e.g. Krypton-85) are decreasing. The impact of reduced atmospheric trace gas concentrations on precision and uncertainty of age dating are investigated. Methods for the quantification of uncertainties and approaches for data analysis are presented. The uncertainty analysis is based on the application of different residence time distributions (piston-flow, exponential, advection-dispersion models and combined thereof) for trace gas concentrations and trace gas ratios. Different ways forward are presented to solve the problem of age ambiguity and increased uncertainty: the use of trace gas ratios is demonstrated and their potential of separating pre- and post-peak samples; the combined use of CFCs with additional tracers such as SF6 and 3H are discussed. While both SF6 and tritium have technical limitations themselves, such as multi-finality and observed deviations from the input function, benefit can be gained by combining them with other tracers or combined data analysis approaches. The quantification of uncertainties and of the adaptation of stringent data analysis provides a basis for the use and critical evaluation of CFCs as water age dating methods in the future.
• Weiler, M., Gimbel, K.
  The Influence of Plants on the Isotopic Composition in Runoff
  2010 American Geophysical Union 2010 Fall Meeting, pages: H51B - 0885
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  Abstract

  The analysis of the stabile isotopes deuterium and oxygene-18 has been available for process research within the hydrological cycle for many decades and provided process and system knowledge about flow pathways, residence times, mixing and redistribution of water. It is commonly assumed that plants do not alter the isotopic signal and therefore plants are usually not considered in hydrologic models. Nevertheless, there are plant-induced processes known by biologists and plant physiologists that have the potential to influence the isotopic composition. Understanding processes and integrating them into a hydrological concept can help to provide a better understanding of acquired isotope data and system behaviour. The analysis presented in this study revealed eight different plant induced mechanisms, which can be grouped by their site and nature in redistribution, selection, leakage and uptake effects. Depending on plant species, habitat conditions and surrounding meteorological parameters, the effects have been reported to have the potential to alter the isotopic content up to 2.0 ‰ δ18O and 9.0 ‰ δ2H, respectively. Using a simple process-based model, it was reviewed quantitatively, which of the plant-associated isotope effects eventually have the potential to modify the isotope signal of catchment runoff. A soil-vegetation-atmosphere model has been chosen, in which processes have been realized via constituent modules that are built on first-order principles. The model’s achievements lead to the conclusion that six of the eight processes may have a significant influence on the isotopic signal in the runoff. The maximum enrichment amounted to -0.42 ‰ δ18O through fog drip and to -2.73 ‰ δ2H through snow interception enrichment. A maximum depletion in the volume weighted means revealed the root water extraction from distinctive depths with 0.58 ‰ δ18O and 3.97 ‰ δ2H in contrast to the volume weighted means of the precipitation input.
• Mueller, P., Creutzfeldt, B., Guentner, A., Merz, B., Weiler, M., Voelkel, J.
  The role of preferential flow in soils along a hillslope dominated by periglacial slope deposits, Bavarian Forest (Germany)
  2010 EGU General Assembly 2010, volume: 12, pages: EGU2010 - 12104
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  Abstract

  Periglacial slope deposits are an important hydrological landscape feature of mid mountain areas in Germany. The stratification of these deposits (Upper Head, Middle Head and Lower Head) determines the infiltration and flow process along the hillslope. Preferential flow processes are closely related to the characteristics of these periglacial slope deposits and have a significant influence on the soil water regime, but identification and quantification of preferential flow is still a challenging task. In this study we investigate macropore flow and its influence on the soil water regime along a hillslope in the Bavarian Forest, Germany. The aim is to identify and quantify macropore flow along the hillslope by conducting dye tracer tests. Three different grassland sites were chosen along a single hillslope, formed by periglacial processes. Soil profiles were classified according to the lithostratigraphy of periglacial deposits. Soil moisture monitoring systems of TDR and tensiometer profiles were installed in 2007. The sites were subdivided into two subplots and sprinkled with different total rainfall amounts (12 and 24 mm) at a constant rainfall intensity of 12 mm/h. During the sprinkling experiment soil water contents were recorded with ten horizontally installed TDR-probes in different depths. Vertical and horizontal macropore patterns were exposed by excavating and photographing the soil in layers. Flow types and macropore properties were evaluated by digital image and dye pattern analysis. The influence of macropores on soil water dynamics was determined by different hydrological models calibrated against the data of the tracer tests. Modeled soil moisture was evaluated by TDR measurements recorded during the tracer test at each plot. Results show that the sedimentary and soil characteristics as well as the soil water regime differ significantly along the hillslope. The upslope site is complex and heterogeneous with Upper Head and Middle Head over an assumed paleo-soil, whereas the downslope site is dominated by relatively homogenous loess material. Five different flow types were identified at the three different sites. Calculated flow types lead to the conclusion that macropore flow is dominating at both sites, whereas matrix flow plays a more prominent role at the downslope site than at the upslope site. TDR measurements during the tracer tests confirm these results by showing a stronger response of the deeper probes for the upslope site than for the downslope site.

2009

• Rosin, K., Weiler, M., Jost, G.
  Addressing Connectivity in Process-Based Hydrologic Models
  2009 American Geophysical Union 2009 Fall Meeting, pages: H32A - 04
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  Abstract

  Following the partial contribution area concept, runoff is only generated on certain areas in a watershed with specific characteristics. The most commonly used method to predict these areas is the concept of dominant runoff generation processes (DRP), which are in general shallow subsurface flow, Hortonian and saturation overland flow. DRP-based hydrologic models estimate surface and subsurface runoff on the basis of delineations of runoff generation areas. Typically, DRP-based model predictions rely on all runoff producing areas in a watershed, even though in reality not every location is necessarily connected to the stream network. Despite many applications of DRP-based hydrologic models, little attention has been given to the question if runoff generation areas are connected to each other and to the stream network. Furthermore, the effects of ignoring connectivity in DRP-models have not been quantified. This study deals with the following questions: (1) what is the influence of connectivity on timing and volume of runoff generation? (2) Does connectivity affect some runoff generation processes more than others? (3) How do the effects of connectivity vary across watersheds, storm intensities and types (summer storms, rain on snow or snowmelt)? (4) Which model complexity is required to adequately represent connectivity? We address these questions by analyzing six model structures for five mesoscale watersheds with different DRP in south-eastern British Columbia. First, we evaluate three connectivity approaches (no, time-independent, and time-dependent connections) for simple DRP-model structures with runoff coefficients. Second, we introduce model structures with more realistic process representations for each DRP, which are tested in combination with the three levels of connectivity. Field data from two climate stations and 19 snow sampling sites were used to produce a fairly accurate spatial-temporal input pattern for the DRP-models, which are executed for periods from 2005 to 2008 at hourly time steps. This study provides a method how to assess and quantify the role of connectivity in process-based DRP models, and how to select appropriate connectivity approaches in process-based rainfall-runoff models.
• Hartmann, A., Lange, J., Rimmer, A.
  Applied dual porosity concept for large karst basins in the east Mediterranean
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 682
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  Abstract

  One of the most problematic aspects of modeling karst hydrology is the “system identification”, which is the conceptual structure of flow within a karstic system. In this study we simulate the conceptual flow system of two large karstic springs, which originate in the karstic region of the Hermon Mountain (Northern Israel). These springs contribute 300 million m3 annually, nearly 70% of the flow to the Upper Catchment of the Jordan River. Our findings are supported by daily measurements of spring discharge and weekly measurements of geochemical components over 35 years. The model couples the groundwater flows of these springs with mixing equations, and applied them simultaneously to both spring discharges and to three different solute concentrations. The conceptual karstic groundwater routine includes two small and fast-reacting reservoirs representing the springs’ conduit systems, and one large and slow-reacting reservoir representing the fissured-porous system (dual porosity concept). Both conduit reservoirs exchange flow with the fissured-porous system, which is linearly dependent on their difference in hydraulic potential. Thus flow between the conduit reservoirs and the fissured-porous reservoir is possible in both directions. Moreover, based on the real hydrological system, it was assumed that one conduit reservoir was located significantly higher than the conduit reservoir of the other. The model enabled the simultaneous solution of the spring flows and concentration of Nitrate [NO
• Wagener, T., McGlynn, B. L., Gooseff, M. N., McGuire, K., Meixner, T., Weiler, M., Marshall, L. A.
  Challenges and Opportunities for Hydrology Education - The Blue Book, Now and the Future
  2009 American Geophysical Union 2009 Fall Meeting, pages: H23K - 08
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  Abstract

  ‘It takes a village to raise a child’, but who does it take to educate a hydrologist who can solve today’s and tomorrow’s problems? ‘Hydrologic science is, by its very nature, interdisciplinary’ (Eagleson et al., 1991, ‘The Blue Book’) and therefore Eagleson and colleagues demanded an interdisciplinary training so that hydrology can achieve its full potential. We believe that, while the demands on current and future hydrologists have increased continuously, their training at both undergraduate and graduate level has not kept pace. How do we, as university faculty, educate hydrologists capable of solving complex problems in an interdisciplinary environment considering that current educators have often been taught in narrow traditional disciplines? These barriers can only be broken down through a unified community effort to change the way in which hydrologists are educated. As the complexity of the task has evolved, so has the complexity of the analysis techniques and tools required for solving emerging problems, and thus so have the difficulties involved in providing the appropriate education (while considering other demands on faculty time). To support hydrology educators in this effort, we have started a faculty community of educators (REACH) and implemented the Modular Curriculum for Hydrologic Advancement (MOCHA, http://www.mocha.psu.edu/). The goal of this effort is to support hydrology faculty in educating hydrologists that can solve interdisciplinary problems that go far beyond the traditional disciplinary biased hydrology education most of us have experienced as students. Our current main objective is to create an evolving core curriculum for university hydrology education, based on modern pedagogical standards, freely available to and developed and reviewed by the worldwide hydrologic community. Further, we seek to establish an online faculty learning community for hydrology education and capacity building. In this presentation we discuss the results of a recent survey on current hydrology education (to compare with the state of hydrology education in 1991), show initial results of this new educational effort, and discuss future opportunities in connecting hydrology education and research based on the interdisciplinary hydrology educations needs outlined by Eagleson et al. (1991).
• Davila, P., Kuells, C.
  Combined application of 85-Kr, 39-Ar with CFCs in contaminated aquifers
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 1074
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  Abstract

  CFCs (11, 12, 113) and SF6 have been used for age dating of recent groundwater (<50 years). It is known that in reducing environments degradation of CFCs occurs. The application of CFCs and SF6 as age indicators in highly industrialized areas of South-Western Germany has shown that in combination with hydro-chemically robust trace gases (SF6) and additional age dating methods (85-Kr, 39-Ar, 3H in-growth method) CFCs and CFC ratios can also be helpful in characterizing the contamination sources and hydro-chemical aquifer conditions. CFC ratios may reveal different sources of contaminations and help characterizing their source type directly. The change of concentrations and of ratios compared to benchmark tracers of mean residence time also provide information on relative CFC reduction. Multi-tracer studies from the Upper Rhein Graben demonstrate the combination of CFC/SF6 analysis with additional residence time indicators, stable isotope and hydrochemical data. While source areas and different flow components can be derived from stable isotopes and hydrochemical data, trace-element chemistry was used to define and characterize redox conditions. Residence time determination with hydrochemically inert tracers (39-Ar, 85-Kr, 3H) provided information on mean residence times that could be used as a scale for CFC reduction. In combination the multi-tracer study helped to derive a semi-quantitative flow model based on environmental tracers.
• Weiler, M., Grether, M., Blattmann, E
  Discharge gauging without a hydrologist
  2009 American Geophysical Union 2009 Fall Meeting, pages: H11F - 0900
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  Abstract

  Discharge data are still the core variable for any hydrological research. Sensors to continuously observe water level in streams have become cheap and their set-up without any hydraulic gauging structure is fast and relative easy. Thus it should be possible in the future to gauge and observe a large variety of watersheds, to learn from the collected datasets, and consequently to overcome the problem of ungauged watersheds. However, the major challenge remaining is to develop a reliable stage-discharge relationship that does not require manual discharge measurements over many years at high costs to the hydrological services. This challenges in particular concerns remote areas and turbulent and flashy streams, where hydraulic gauging structures cannot be constructed due to ecological or financial constrains. The stage-discharge relationship in these streams is often poorly defined since the cross-section or hydraulic properties are changing continuously. Especially at high flows a large error has to be assumed since discharge could not be continuously observed. We developed and tested a new instrument for continuous discharge monitoring in turbulent streams. This tool is designed to reliably observe discharge in these streams and to obtain hundreds of discharge measurements to construct a stage-discharge relationship within a couple of weeks. The Automatic Dilution Gauging System (ADiGS) is a self-controlled instrument for dilution gauging using florescent dyes as a tracer. Because of its technical setup with low power consumption, automatic tracer injection, effective data storage and the possibility to transfer or receive data by wireless communication, ADiGS can be used as a stand-alone tool. It can therefore be easily deployed to establish time- and cost-effectively stage-discharge relations in low accessible regions or under financial constraints.
• Kuells, C., Marx, V., Bittner, A., Ellmies, R., Seely, M.
  Environmental impacts on the hydrology of ephemeral streams and alluvial aquifers
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 5517-1
• Brena, A., Schneider, J., Stahl, K., Weiler, M.
  Estimation of low flow sensitivity to climate and land-use changes using a parsimonious water balance model
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 665-1
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  Abstract

  There is considerable interest in systematically estimating the impact of climate and environmental changes to particular characteristics of hydrological regimes across large regions. This study presents the development and first application of a regionalised parsimonious model to estimate the sensitivity of the summer low flow period in British Columbia, Canada. Here, summer low flows are maintained through the release of water from groundwater storage, flow from channel banks, lakes and wetlands. Low flows are important for water-supply planning and design, and maintenance of quantity and quality of water for irrigation, recreation, and fish and wildlife conservation. There have been concerns recently that climate warming and land cover changes due to an unprecedented pine beetle epidemic may cause a deterioration of water quality during low flow periods and at certain times may become a hazard to ecosystem and to water management schemes. A parsimonious water balance model based on a simple transfer function approach was developed to characterize the recession curve of the hydrological regime. The purpose of the model is to transform a distributed effective water input into a characteristic hydrologic regime at the outlet of the catchment. The distributed effective water input is derived from gridded 30-year mean monthly precipitation and temperature data (disaggregated to a daily resolution) that is first modified by evapotranspiration and by a degree-day based snow accumulation and snowmelt model. The two model parameters of the non-linear transfer function were fitted to the characteristic hydrographs of a sample of gauged catchments with different size, elevation, climate, and hydrological regime. Based on their relation to catchment characteristics, the model parameters were then regionalized for a large area of British Columbia. A first application estimates the sensitivity of the low flow season to simple delta-change climate scenarios for third-order watersheds in the region. The potential of the model as low flow change prediction tool is assessed considering uncertainty estimates. In particular regions, hydrological persistence provides some limitations.
• Stahl, K., Gudmundsson, L., Tallaksen, L.M.
  Hydrological drought characteristics in catchments: to what extent are they reproduced by regional climate models?
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 8023
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  Abstract

  Land surface schemes and large-scale hydrological models have been compared mostly with observed streamflow records from large basins that aggregate small-scale hydrological variability. However, high-resolution regional climate model output is now becoming more readily available and hence more likely to be used and interpreted at smaller scales, relevant for example for hydrological process studies and catchment scale drought management. The streamflow data set of the recently updated European Water Archive (EWA) includes recent droughts such as in summer 2003 and hence provides the opportunity to test the limits for such use. For this purpose we identify suitable benchmark statistics to compare observed characteristics of hydrological drought with those from flow-constituting variables of the 0.12 degree resolution European re-analysis performed for the EU-WATCH project (by DMI with the HIRHAM5 model). We present results for different regions in Europe testing to what extent (a) drought events in the meteorological and hydrological variables occur simultaneously in space and time and (b) the distribution properties of drought characteristics are comparable. Regional differences in the comparability of RCM simulated hydrological drought with observations from catchments may allow to classify the relative importance of competing influences of climatic drivers and local catchment storage on drought and low flows.
• Klaus, J., Kuells, C.
  Integrating residence time data in mixing cell modeling – Application to the Lower Kuiseb Dune area
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 11026
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  Abstract

  With few exceptions, only limited hydrologic data are available in regions with the highest scarcity of water. Especially in basins with limited data on hydrogeological structure, it is difficult to accurately characterize groundwater flow systems and their recharge sources. Therefore, estimation of available water resources in drylands requires methods that are based on existing data and on information that can be obtained with affordable efforts. Even in desert regions chemical and isotope data are often available or can be obtained quickly. In this study a mixing cell approach was extended by a method incorporating mean cell residence times derived from 14C to further constrain and validate the modeling results. This extended approach was used to model the groundwater system of the Lower Kuiseb Dune area in Namibia. The Kuiseb is a 560 km long ephemeral river crossing the Namib Desert from east to west. Transmission losses from the riverbed during flood events are an important source of groundwater recharge to the underlying aquifer system. Hydrochemical data from 13 wells in the area were used. End members were identified as sources for groundwater found in the Lower Kuiseb, including inflow from the crystalline basement plateau north of the Kuiseb as well as floodwater from the Kuiseb River. A conceptual groundwater recharge and flow model was developed, and then inverse mixing cell modelling was carried out using hydrochemical tracers. This approach generally allows for several possible solutions and leads to model equifinality. After completing the inverse modeling, a forward mixing cell model was developed by varying the mean residence time of each cell to fit calculated 14C data to the measured 14C data. With the additional use of 14C in the mixing approach the number solutions could be narrowed down for most of the different cells. As a important result it was possible to calculate the fractions of floodwater in the different cells of the aquifer beneath the Kuiseb. The floodwater fraction was shown to be between 85.2% and 98.2% for the upper aquifer cells and between 61.0% and 75.2% for the lower aquifer cells. This results show also that there is an important amount of recharge by sources except floodwater. This new approach joins previously developed methods solely based on conservative mixing or residence time optimization. Is very useful in reducing equifinality in the mixing cell modelling and gave important and new insights in the sources of groundwater recharge in the Lower Kuiseb aquifer system.
• Schwerdtfeger, J., Johnson, M.S., Weiler, M., Couto, E.G.
  Isotopic Estimation of Water Balance and Groundwater-Surface Water Interactions of Tropical Wetland Lakes in the Pantanal, Brazil
  2009 American Geophysical Union 2009 Fall Meeting, pages: H41E - 0948
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  Abstract

  The Pantanal is the largest and most pristine wetland of the world, yet hydrological research there is still in its infancy. In particular the water balance of the millions of lakes and ponds and their interaction with the groundwater and the rivers are not known. The aim of this study was to assess the hydrological behaviour between different water bodies in the dry season of the northern Pantanal wetland, Brazil, to provide a more general understanding of the hydrological functioning of tropical floodplain lakes and surface water-groundwater interactions of wetlands. In the field 6-9 water sample of seven different lakes were taken during 3 months and were analyzed for stable water isotopes and chloride. In addition meteorological data from a nearby station was used to estimate daily evaporation from the water surface. This information was then used to predict the hydrological dynamics to determine whether the lakes are evaporation-controlled or throughflow-dominated systems. A chloride mass balance served to evaluate whether Cl- enrichment took place due to evaporation only, or whether the system has significant inflow and/or outflow rates. The results of those methods showed that for all lakes the water budget in the dry season, output was controlled by strong evaporation while significant inflow rates were also apparent. Inflow rates and their specific concentrations in stable isotopes and chloride were successfully estimated using the simple mass balance model MINA TrêS. This approach enabled us to calculate the water balance for the lakes as well as providing an information on source water flowing into the lakes.
• Weiler, M.
  Macroscale Structures and Preferential Flow Networks at the Hillslope Scale
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 665-1
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  Abstract

  Many hillslopes have macroscale structures like root channels or pipes that control their hydrological behaviour. Describing this macroscale structure, its physical properties and how it is generated is important in the advancement of the field of soil hydrology. While progress has been made both experimentally and in modeling network-like behavior at the hillslope scale, the fundamental question remains: Why do lateral preferential flow networks develop? It is hypothesized that emergence of these flow networks at the hillslope scale reflects a self-organized, macroscale flow behaviour. Virtual experiments using the hillslope model Hill-vi will be presented to quantify the linkage between initially unconnected soil pipes and formation of dynamical network structures in time and space. Virtual experiments use the combined knowledge of observed structure (e.g. tree roots) and hydrological dynamics from different places and merge this into a process-based model. The following questions are investigated: 1) What are the underlying mechanisms governing architecture and emergence of soil pipe networks? (2) Are patterns of preferential flow within hillslopes a result of flow optimization? (3) How could preferential flow networks evolve in both space and time? The presented results illustrate some first steps towards a better conceptualization of such complex system in order to be able to predict the hydrological behaviour of preferential flow of lateral subsurface flow at the hillslope scale.
• Gregoire, C.,, Elsaesser, D., Imfeld, G.,, Jezequel, K., Lange, J., Lebeau, T., Merli, A.,, Mose, R., Paineau, F., Passeport, E., Payraudeau, S., Schulz, R., Tournebize, J., Trevisan, M., Wanko, A.
  Mitigation of agricultural nonpoint-source pesticide pollution and phytoremediation in artificial wetland ecosystems (Project ArtWET LIFE 06 ENV/F/000133)
  2009 3rd Wetland Pollutant Dynamics and Control - WETPOL2009, pages: 289 - 290
• Kuells, C., Zabori, J.
  On the representation of hydrological processes in current SVAT schemes - comparison and perspective
  2009 American Geophysical Union 2009 Fall Meeting, pages: B14A - 01
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  Abstract

  The representation of hydrological processes and biogeochemical feedbacks in common soil-vegetation-atmosphere-schemes constrains their response and adaptation to climate change impacts. A comparative study and review of SVAT schemes commonly used for the evaluation of climate change impacts shows that they differ significantly in emphasizing different aspects of hydrological processes and their biogeochemical feedbacks. The categories for which SVAT schemes have been compared include carbon dioxide-transpiration feedbacks, S-N-P nutrient cycles and limits, and hydrological process types (snow hydrology, preferrential flow, runoff processes). The regional distribution of SVAT model applications, the respective range of conditions in which they were developped, tested and calibrated and the access to model documentation, data and case studies were included. A more general perspective on the type of processes that are represented shows that local and vertical process representation dominates and while lateral and regional hydrological phenomena and feedbacks are rarely represented. Also the influence of subsurface systems and their impact on the redistribution of water are often not included. A perspective on the representation of such large scale hydrological storage and redistribution processes for SVAT schemes based on a classification of watershed types is developped.
• Lange, J.,, Arbel, Y., Greenbaum, N., Grodek, T.
  Process studies of water percolation in a Mediterranean karst area
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 11391
• Gudmundsson, L., Lange, H., Tallaksen, L.M., Stahl, K.
  Quantification of Europe-wide streamflow complexity and potential links to atmospheric circulation patterns
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 6299
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  Abstract

  Stream flow observations from a geographical region are known to often exhibit strong common behavior. In order to assess the temporal evolution of the complexity of stream flow time series from all over Europe, we employ the recently developed Linear Variance Decay dimension density ( LV D). It is estimated as the parameter of an exponential decay function fitted to the remaining variances of the eigenvalues of a covariance matrix. Scaling between zero and one, LV D can be interpreted as a measure of the proportion of linear independent components in a multivariate record. We analyze a large set (400) of daily European streamflow series taken from the European Water Archive (EWA), covering the period 1963 to 2005. We compute LV D series for monthly aggregations as well as for a one-year long moving window (at monthly time steps). The resulting two series are highly structured. The series representing monthly LV D values has a distinct annual cycle with the least complexity in the winter months. The series with the running annual LV D values has a significant downward trend that accounts for 37% of the variance. In order to detect oscillatory behavior, we use Monte Carlo Singular System Analysis.We detect two significant oscillatory modes with large spectral power on narrow periodic bands (2.2 - 3.4 and 1.9 -2.9 years). These modes together account for 15% of the variance. In order to seek the origin of these periodicities, we compare them to periodic components of northern hemisphere teleconnection indices. Among a variety of indices explored, the East Atlantic Pattern (EA), the West Pacific Pattern (WP) and the East Atlantic/West Russia Pattern (EA/WR) have modes with significant variability in the 1.9 to 2.9 years band. However only the signal extracted from EA/WR is strongly related to periodic behavior in the LV D series of European stream flow. Thus we conclude that an two to three year oscillation in the EA/WR may drive weather patterns that influence the strength of synchronous behavior of pan European stream flow.
• Gudmundsson, L., Tallaksen, L.M., Stahl, K., Lange, H.
  Regional synchronisation of hydrological regimes – is the variability of extremes linked to mean conditions?
  2009 EGU General Assembly 2009, volume: 11, pages: EGU2009 - 989
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  Abstract

  General questions that arise while investigating hydrological extremes are whether these have distinct spatial and temporal variations and how these variations are linked to mean flow conditions. We analyze a large set of European stream flow series. Based on daily observations we derive annual series of stream flow deciles ranging from the minimum to the maximum, resulting in a set of eleven series for each station representing the year to year variability of the flow regimes. In order to determine common temporal structures we develop a two level strategy: First, matrices of correlations between the annual deciles series of all stations are derived for the eleven decile series between all stations are derived. This leads to a set of correlation matrices representing temporal similarity of the corresponding part of the regime between the different stations. A second step develops the framework of Principal Coordinates of Distance Matrices (PCoDM) that enables to uncover related structures from the set of matrices derived in step one. The resulting generalized similarity matrices (GSM representing between-station similarities) are subject to further multivariate analysis. PCoDM shows that the same structure is dominating the in the between-station correlations throughout the different deciles, except for the series of annual maxima. This shows that within the given geographical region, the flow regime has a synchronized year to year variability, except for the peak flows. The first residual pattern thus is related to the peak flows. The leading GSMs are used as input for cluster analysis. Plotting the clusters of the leading GSM into a geographical map reveals clearly disjunct regions with synchronous behavior throughout all deciles. In contrast, the first residual GSM has large correlations with the extreme deciles and are spatially heterogeneous. The results point to a synoptic-scale climate forcing for a wide range of flow conditions, whereas the upper extreme flows are more influenced by local properties of the individual catchments.
• Szeftel, P., Moore, R. D., Weiler, M.
  Revisiting discharge increments: variability in space and time of water delivery to the stream
  2009 American Geophysical Union 2009 Fall Meeting, pages: H33G - 0963
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  Abstract

  The spatial and temporal variability of water delivery mechanisms to the stream network was examined in the Cotton Creek Experimental Watershed (CCEW), a 17 km2 snow-dominated watershed located in south-eastern British Columbia, Canada. Our objectives were 1) to determine the first order controls on water delivery mechanisms from the scale of the slope to that of the whole watershed and 2) to highlight the shift in nature of these controls as the flow regime evolves from freshet to low flow. Following a scale connecting approach, we conceptualized the watershed as an aggregation of incremental contributing areas (ICAs), each representing the incremental addition of drainage area along a stream reach. Cotton Creek’s stream network was divided into 23 reaches, with ICAs ranging from 0.05 to 2.7km2 in size. Stream discharge was measured at both ends of each reach in order to compute flow increments, the net water budget over the length of the reach. Streamflow gauging campaigns were repeated from freshet to baseflow periods for years 2005-2008. Preliminary investigations showed that lateral contributions from ICA were highly variable both in space and time. Through a Principal Component Analysis, this variability was related to the annual forcing (snowmelt) and the individual recession characteristics of ICAs. During the wet state of the catchment, ICA contributions were moderately explained with contributing area. Topographic controls, especially contour curvature controlled ICA contributions during intermediate wetness states. Controls on water delivery during low flows were difficult to identify, probably due to a great uncertainty characterizing discharge measurements and resulting discharge increments. This approach permits the observation of emergent behaviors between the ICA and watershed scales. It also offers a temporally dynamic definition of first order controls on water delivery to the stream network, which can help refine hydrological models.
• Stahl, K., Moore, R. D., Allen, D. M., Whitfield, P. H.
  Separation of Changes in Hydroclimatic and Basin Controls on Late-Summer Low Flow in British Columbia, Canada
  2009 American Geophysical Union 2009 Fall Meeting, pages: H24B - 07
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  Abstract

  For catchments in the Pacific Northwest of North America with minimal or no glacier cover, the summer period is typically dominated by low flows associated with the relatively warm, dry summers in that region. In recent years summer low flow has become more critical in terms of water use and fisheries, and there is increasing concern regarding effects of future climate change. In particular, it is expected that earlier snowmelt timing in spring causes longer recession periods and consequently lower streamflow during late summer. This study examined the sensitivity of late summer flows of 153 ‘unregulated’ rivers over the period 1976-2003 to hydroclimatic influences using trend tests accounting for exogenous variables by regression. Regression models were fitted using simultaneous and lagged variables of precipitation and timing and magnitude of snowmelt. The residuals were tested for trends and serial correlation to assess potential secondary influences such as long-term groundwater storage changes or mid-term changes in evapotranspiration. The decrease in September flows found across most of the region is broadly consistent with a decline in September precipitation. The most important control on August flows for all streamflow regimes is August precipitation. The influence of lagged variables including snowmelt timing varies. Rain-dominated and hybrid catchments along the coast tended to have positive trends in their residuals in August, suggesting an increasing trend in groundwater storage. Snowmelt dominated catchments show varied trends but the runs test detected a substantial number of stations with non-random residuals, suggesting mid-term secondary influences possibly associated with evapotranspiration changes due to progressive forest harvesting. This regional study greatly improves the understanding of the hydroclimatic influences on extreme summer low flow in the region. Results suggest that (the less predictable) summer climate is a larger influence than previously assumed. They also help to identify where seasonal snow processes, long-term groundwater storage, or vegetation changes should be considered in model development, forecasting, and prediction of climate change impacts.
• Weiler, M.
  Should the landscape or the modeler define hydrological model structure?
  2009 American Geophysical Union 2009 Fall Meeting, pages: H23L - 09
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  Abstract

  In most applications of hydrological models the same model structure is applied everywhere even though the model is unable to provide a faithful description of all occurring hydrological processes. Insights gained from experimental hydrology are rarely used directly to define the structure of hydrological models. Instead, more complex, distributed physically-based models use simple look-up tables to relate the parameters of each structural model element to soil and land-cover information without sufficiently evaluating these relationships. Still, the models are expected to generate the correct processes pattern within the landscape based on the fixed model structure with local parameterization. However, as for example the generation of surface runoff shows, the resulting pattern of the process is often incorrect because the model fails to predict the variable dynamics of soil saturation correctly. Another approach could be to have the landscape and climate define the model structure and hence directly guide selection and description of relevant hydrological processes. From our long experience in experimental hydrology we have collected a wealth of knowledge and data to predict, for example, if a specific hillslope that has developed over a known geologic formation within a specific climate generates surface or subsurface runoff during a storm. If we are able to predict the location of dominating hydrological processes based on landscape information, we could use this “map” of hydrological processes to define or adjust the model structure representing a specific process. This approach would be particularly powerful in ungauged basins. This contribution will compare the two approaches, introduce different methods how landscape can define model structure, and discuss strategies to identify regional differences in perceptual models and to determine the suitability of different model structures in different regions.
• Kelleher, C., Wagener, T., Gooseff, M. N., Gregg, S., McGlynn, B. L., Sharma, P., Meixner, T., Marshall, L. A., McGuire, K., Weiler, M.
  Toward an Online Community of Educators: The Modular Curriculum for Hydrologic Advancement (MOCHA)
  2009 American Geophysical Union 2009 Fall Meeting, pages: ED31A - 0522
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  Abstract

  The field of hydrology encompasses a wide range of departments and disciplines, ranging from civil engineering to geography to geosciences. As a consequence, in-class hydrology education is often strongly biased towards the background of a single instructor, limiting the educational experience of the students and not allowing for a holistic approach to hydrology education. Recently established, the Modular Curriculum for Hydrologic Advancement (MOCHA) creates an online community of hydrologists from a range of backgrounds and disciplines to define the boundaries of an unbiased hydrology education and to jointly develop resources to overcome previous instructional limitations (http://www.mocha.psu.edu/). Our first objective is to create an evolving core curriculum for hydrology education freely available to, developed, evolved and reviewed by the worldwide hydrologic community. On a larger scale, we hope to raise the standard of hydrology education and to foster international collaboration and exchange. Our work began with an initial survey including over 100 hydrology educators to assess the state of current hydrology education. Based on the survey results, the MOCHA project was designed and implemented, and initial teaching material and pedagogical guidelines for good practice in teaching were prepared. This past fall and spring, we piloted the website and teaching material across several universities. The web-based MOCHA project has recently been opened to solicit contributions from the global hydrology community. Our presentation will focus on the overall vision behind MOCHA, lessons learned from our initial piloting, and current steps to achieve our vision.

2008

• Jost, G., Moore, R. D., Weiler, M., Alila, Y.
  A Combined Statistical and Mechanistic Modeling Approach to Study the Effect of Clear- cutting in a Snow Dominated Watershed
  2008 American Geophysical Union 2008 Fall Meeting, pages: H12A - 04
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  Abstract

  Scientific investigations to predict the impact of land cover changes have traditionally employed paired watershed studies in which streamflows are monitored before and after land cover changes. The paired watershed approach requires monitoring periods that are often too long to address urgent forest management questions such as those related to pine beetle infestations. Because internal hydrological processes are not revealed using this black-box approach, the why and why not is often left to speculation. In recent years, distributed models have been used more often to address the influence of land cover changes on hydrology. However, most model applications rely on stream discharge at the outlet and meteorological or internal process data at one or a few locations, so that the why and why not is still left to speculation. Detecting and simulating the effects of land cover changes requires an improved procedure to measure inputs and internal processes in watersheds. In this study we introduce the experimental design to predict the influence of clear-cutting for a 17.4 km2 forested watershed in south-eastern British Columbia (Canada) with a distributed hydrological model. The study design includes discharge measurements at 10 nested sub- basins, 8 climate stations to capture variability in climate forcing, and spatial snow surveys at 25 locations in bi-weekly intervals during snow cover depletion. The input and internal process data from 4 years are used to stepwise calibrate the distributed hydrological soil and vegetation model (DHSVM). The ability of DHSVM to reproduce the main topographical gradients for snow accumulation and snow melt, the two most important hydrologic processes in a snow dominated watershed, is tested by spatial regression analysis with measured snow water equivalents. For different clear- cut scenarios, a stream flow time series is simulated, from which the peak flows are extracted. The experimental design enables us not only to predict the effect of harvesting different equivalent cut areas (ECA), but also how to optimally place cut blocks in a watershed in order to maximise ECA and minimize the effects on streamflow.
• Passeport, E., Lange, J., Tournebize, J., Chaumont, C., Birgand, F., Vincent, B.
  Agricultural drained watershed effluents: a tracer experiment for hydraulic characterization of an artificial wetland as pesticide mitigation system
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-00795
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  Abstract

  With intensive agriculture, better crop yields were obtained thanks to artificial subsurface drainage of some easily water-saturated lands and a wider use of pesticides. This lead to ground and surface water pollution by these active substances which is now a global environmental stake. To meet European water quality guidelines (Water Framework Directive 2000/60/EC), mitigation strategies should be considered. Pesticide agricultural non-point source pollution could be mitigated by implementing several measures at different scales. This project focuses on complementary measures to application reduction ones. As part of a LIFE ArtWET project (www.artwet.fr), two on-site pilot buffer systems, an artificial wetland and a forested plot (at Bray, Indreet- Loire, France) are monitored to determine their pesticide mitigation efficiencies. The systems are located at the outlet of a 42 ha artificially drained crop watershed (wheat, barley, rape) where a majority of herbicides is applied each year. The main objectives are to understand wetlands functioning and provide optimization guidelines to improve water treatment in such rustic systems. Inlet and both outlets are monitored to get flow-rate measurements and flow-weighted composite samples which are analysed for pesticides. To ensure system maintenance and functioning, it was chosen to get the watershed farmer collaborative involvement. By means of a removable PVC elbow, the farmer is in charge of opening subsurface drainage water entrance to both buffer wetlands before the first storm events following pesticide applications. For systems’ functioning understanding and optimization, laboratory and field work is planned. A tracer experiment is scheduled, to assess hydraulic and pesticide retention times as well as main water pathways in the wetlands. This experiment will help determining if wetlands’ hydraulic functioning is satisfactory on two main points. The first one is to ensure retention time long enough for pesticide biodegradation; secondly, it is necessary to know the main pesticide pathways to assess if the contact surface with soil or sediment matrices is high enough for pesticide immobilization.
• Weiler, M., Rosin, K.
  Assessing Sensitivity to Forest Disturbance in Ungauged Basins
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-04784
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  Abstract

  Forest cover is a key modifier of a watershed’s peak flow regime. Where forest cover is reduced due to logging or natural disturbances such as fire, insect, or disease outbreaks, peak flows are increased in most cases. Based on GIS data available for the entire province of British Columbia (BC), Canada, with its diverse climatic regimes, land cover and hydrologic processes, we developed a novel methodology that classifies the sensitivity of watersheds to peak flow modification based on input characteristics and hydrological runoff generation processes for ungauged watersheds. The input model component uses climatic data to derive mean annual snowmelt and maximum rainfall rates for BC for each month at a 400m grid resolution. It estimates the time of occurrence of snow-melt induced peak flow, and classifies watersheds into snowmelt-dominated, rainfall-dominated, and transitional precipitation regimes. This allows mapping peak flow generating input for each third-order watershed in BC. The runoff generation model component delineates dominant peak flow generating processes at the watershed level: channel interception, Hortonian Overland Flow, Saturation Overland Flow and Shallow Subsurface Flow. This delineation is based on a combination of factors such as land cover, relief, slope, aspect, drainage density, drainage pattern, and hillslope morphology. The model components have been successfully validated against provincial hydro-climatic data sets. Derived maps at 25 m resolution are used to classify the watershed into different peak flow regimes to obtain a sensitivity rating for different disturbance scenarios. This rating is incorporated into a framework to assess risks to infrastructure, drinking water, and fish habitat, and to minimize peak flow modification by optimizing timing, extent and location of logging in watersheds. This approach provides a novel combination of spatially explicit hydrological process mapping in ungauged watersheds and scenario generation for a variety of land cover changes.
• Rosin, K., Ilchmann, N., Asadian, Y., Weiler, M.
  Catchment Classification Based on Runoff-Generation Processes for Different Climate Regimes
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-05719
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  Abstract

  Appropriate catchment classification is considered to advance runoff modelling, since it can improve model selection and evaluation, especially in ungauged basins. With the Sensitive Area Mapping Model (SAMM), we classify watersheds for the entire Province of British Columbia (945,000 km2) in Canada according to the dominant runoff-generating processes. In a hierarchical framework, runoff-generating processes are represented by parsimonious model structures, which are based on topographic and physiographic data. For the example of Saturation Overland Flow (SOF) we discuss the following questions: (1) Which model structures lead to classifications which agree best with reality? (2) What is the level of uncertainty we should a-priori take in consideration? For both questions, we are interested in providing answers for different climate regimes, since our process classification is mainly based on topographic data. Therefore, model structures and parameter sets have been evaluated for four catchments in British Columbia with different climate and precipitation regime. At more than 400 locations soil samples, indicator plants, and small scale morphology patterns which determine SOF occurrence have been mapped and analyzed. The results show how our topography-based process classification system can be applied for catchments in different climates. Based on Kappa statistics, we furthermore specified the uncertainties associated with our classification system. In summary, the new results allow us to apply a process-based classification in combination with the SAMM model to predict the effects and uncertainties of large scale forest disturbance and land-use change on hydrology in large, ungauged basins in British Columbia.
• Klaus, J., Kuells, C., Stichler, W.
  Changes in isotopic composition of precipitation in Germany during the last three decades
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-08158
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  Abstract

  Climate scientists have concluded that the earth’s surface air temperature increased by 0.6 C during the 20th century, and that warming induced by increasing concentrations of greenhouse gases is likely to continue in the 21st century, inducing changes in the hydrologic cycle. Various studies were conducted to detect changing hydrological parameter by time series analysis. However, there is a lack of information about the behaviour of isotopic composition of precipitation during the 20th century, even though knowledge about this behaviour is very important for hydrological research. Therefore, the monthly O-18 time series of selected stations in Germany have been analysed for decadal trends as potential indicators of changes in the hydrological cycle. Only eight stations supplied sufficiently long time series to perform statistical trend test analysis. The period of the study covers 1978-2006. The non-parametric Mann- Kendall test was used to calculate the significance (p 0.1) of trends. The method of Sen was applied for the calculation of the direction and magnitude of trends. Corrections for serial correlation were carried out. In northern german inland stations a strong change was detected for January to June, with the highest rate of change during March in Braunschweig (0.161 0/00/yr, p=0.001). Those inland stations showed slight lighter isotopic composition of precipitation from August to December with no significance compared to the beginning of the time series. The only station located at the coast (Cuxhaven) showed significant changes only in June and July. The southern german stations of Stuttgart andWuerzburg showed a similar behaviour with significantly heavier precipitation in June and lighter ones in September and November. Isotopic compositions in the northern Alps became significantly heavier from March to June with a maximum change of 0.179 0/00/yr in April, which led to 5.2 0/00 heavier isotope signature of April precipitation compared to the late seventies of the last century. Preliminary results showed a partial relationship between the strength and direction of the temperature trends to the trends of the isotopic composition of precipitation (R2=0.39). But this relation can not explain the strong change in isotopic composition of precipitation on it’s own. The changing isotopic composition must be considered during studies handling longer isotopic time series of groundwater and river runoff, because the precipitation probably also leads to trends in groundwater and runoff isotopic composition.
• Keim, R. F., Weiler, M., Jost, G., Tromp-van Meerveld, I.
  Consequences of Spatiotemporal Redistribution of Precipitation by Vegetation for Hillslope and Runoff Processes
  2008 American Geophysical Union 2008 Fall Meeting, pages: H14A - 03
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  Abstract

  The effects of vegetation on streamflow generation are currently best understood in terms of how evaporation from canopy interception and transpiration affect watershed-scale responses at timescales of individual storms or longer. Examining processes at finer temporal and spatial scales suggests that spatiotemporal redistribution of precipitation by forest canopies within storm events may have important consequences for transient pore pressures and runoff generation. Temporal variation in rainfall intensity is reduced in throughfall because canopies act as reservoirs that temporarily increase storage during short bursts of high-intensity rainfall; effective hydraulic mean residence times may be 20 minutes or longer in dense canopies. Modeling indicates this intensity smoothing reduces the development of high soil pore pressures responsible for initiation of shallow landslides and has a small effect on peak storm discharge. Associated with temporary storage in the canopy is lateral redistribution that results in spatial patterns in throughfall that persist over time and cause spatial variation in soil moisture. Modeling indicates that throughfall or stemflow infiltrating disproportionately into zones of high soil moisture causes a positive feedback that speeds runoff response and reduces total soil water storage. Few watershed models incorporate these spatiotemporal nonlinearities directly, though more work is needed to understand how these processes influence runoff at the watershed scale and across a range of ecosystem structures.
• Gascuel-Odoux, C., Weiler, M., Molenat, J.
  Effect of different spatial models of physical properties on water table dynamics and stream discharge
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-05691
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  Abstract

  Physical properties are often assumed to be homogeneous over the catchment or hillslope when modeling discharge and water table dynamics.We hypothesize that this assumption often results in poor simulations of water table depth dynamics, particularly in upslope position. This hypothesis is rarely tested due to lack of water table observations in the upslope area. We present a study that tests the effect of different spatial models of the saturated hydraulic conductivity and drainable porosity. The study was located in an experimental watershed underlain by schist crystalline bedrock where shallow and perennial groundwater develops mainly in the weathered layer of the bedrock. Groundwater observation wells were drilled along the hillslope transect to a maximum depth of 15m and continuously monitored. We used the physically-based hillslope model Hill-vi to simulate water fluxes in the unsaturated and saturated zone, the water table dynamics at different slope positions and the discharge. Four different spatial models were considered assuming different landscape controls on saturated hydraulic conductivity and drainable porosity.We used Monte Carlo simulations within a multiobjective framework to compare the different model structures and determine the best overall model based on discharge and the comparison between average water level and range in variations among three wells. The results demonstrate that all models were able to capture the discharge and water table dynamics observed in the downslope wells, but the water table data from the upslope region of the watershed (plateau or ridge) was more difficult to predict. In this upslope region, however, the large annual water table variations of 4-6 m have significant effects on nutrient and contaminant transport and also on residence time variations.
• Weiler, M., McDonnell, J. J.
  Emergence of Preferential Flow Networks at the Hillslope Scale
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-04396
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  Abstract

  Several experimental investigations and simulations have shown that the hydrological behavior, in particular in steep, forested watersheds, is controlled by macroscale hillslope structure. Weiler and McDonnell (2007, WRR) recently developed and applied a model to the Maimai hillslope, NZ, that describes such macroscale structure as often inherent in a lateral preferential flow (pipe) network. The work clearly demonstrated that even disconnected preferential pathways can connect to develop a network-like flow pattern. Describing this network structure, its physical meaning, and how it is generated is important for the advancement of hillslope hydrology. In this study, hillvi, the model developed to simulate the network-like behavior at the hillslope scale, was used to investigate emergence functional properties of these networks. A virtual experiment to investigate different relations between soil matrix and pipe conductivity was set-up using soil, topographical and meteorological data from the Maimai hillslope. The simulation results demonstrate that, while for different combinations of matrix and pipe flow conductivities the subsurface flow response can be very similar, the internal development of a flow network and the importance of pipe flow will differ. The distributions of lateral flow velocity in the hillslope during peak flow and during drainage of the hillslope are distinctly different for the different combinations. This will have interesting implications to the modeling of transport processes in network dominated hillslopes as a strongly skewed distribution develops for certain combinations. Similar observations were made for pore water pressure, which may have important implications for slope stability assessment. The results raise the question if a deterministic framework like Bejan’s constructal law, hypothesizing that the configuration of the pipe flow networks must evolve such that flow pathways maximize the amount of flow through a hillslope or other network theories, can be supported in light of our simulations.
• Kuells, C., Heidbuechl, I.
  Groundwater controls on flash flood shape and incidence
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-11123
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  Abstract

  The development of a fully coupled flash flood routing and numerical groundwater model for ephemeral streams and alluvial aquifers indicated that in semi-arid and arid environments aquifer properties and groundwater level control flash flood shape and incidence. A series of small, medium and large flash flood waves were routed through alluvial aquifers with varying characteristics such as aquifer thickness, hydraulic conductivity, depth to water table and width. The numerical study indicated that general relationships between flash flood shape, incidence and aquifer properties exist. The coupled modeling showed that especially the steepening of the rising limb of flash floods was related to transmission loss dynamics depending on specific aquifer properties. It could be shown that the characteristic steep front of some flash floods resulted from a sharp cessation of infiltration during the early phase of flash flood transmission and, hence, is linked to hydrogeological characteristics that can be evaluated based on field work or pre-event monitoring. Also the significant impact of antecedent hydrogeological conditions on flash flood size and shape could clearly be demonstrated. In summary, flash floods generation, besides meteorological and catchment related properties, is affected by predictable hydrogeological factors. Systematic and predictable relationships between alluvial aquifer properties and flash flood characteristics exist in dryland ephemeral rivers. The knowledge on aquifer and groundwater control on flash floods can help improving the assessment of flash flood risk.
• Gassmann, M., Lange, J., Schütz, T.
  High resolution assessment and modelling of suspended sediment in an agricultural catchment
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-09116
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  Abstract

  Following high intensity rainfall, surface runoff and soil erosion may mobilize large amounts of pesticides from agricultural areas. To accurately assess pesticide removal from small catchments high resolution measurements are required, since typical storm events only last for several hours. As the main carrier of contaminants, suspended sediments play a key role. In a 1.8 km2 agricultural catchment in south-west Germany continuous measurements of runoff, turbidity and suspended sediment were carried out to calibrate a catchment-scale erosion- and sediment transport model. Soils have developed from aeolian loess with a silt fraction exceeding 80%. An extensive 9 km pipe network connects terraces with gently sloping vineyards to a 2 km stream with fixed banks and channel bed. Hence in-channel erosion can be neglected and the present study area may be seen as field laboratory to investigate processes of sheet erosion at catchment scale. During several events continuous turbidity measurements were related to suspended sediment concentrations (SSC) collected by an automatic sampler at the catchment outlet. Compared to laboratory measurements, the obtained turbidity-SSC-relation was relatively weak but more applicable to field conditions and resulted in a time series of SSC for a later model check. For modelling, the rainfall-runoff model ZIN was supplemented by a distributed erosion/sediment transport module. The USLE (Universal Soil Loss Equation) described sheet erosion depending on rainfall intensity, average slope and vegetation impacts. Existing data on sprinkling tests served for model parameterization. Sediment yields per time step and cell were transferred to the adjacent pipe or stream using a simple transfer function. Finally, inside the pipe- / channel network, the sediment wave was routed to the outlet using the Muskingum-Cunge routing procedure. Model checks against measured runoff and SSC time series data were promising. Hence the present approach adequately described the driving processes of water and sediment dynamics and may be used as a basis to predict pesticide mobilization from intensive agriculture.
• Stahl, K., Moore, R. D., Allen, D.M., Whitfield, P.
  Hydroclimatic controls on late-summer low flow in British Columbia, Canada
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-04837
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  Abstract

  For catchments in the Pacific Northwest of North America with minimal or no glacier cover, the summer period is typically dominated by low flows associated with the relatively warm, dry summers in that region. In recent years streamflow during this period has been critical in terms of water use and fisheries, and there is increasing concern regarding how future climate change may affect late-summer flows. In particular, it is feared that earlier snowmelt timing in spring causes longer recession periods and consequently lower streamflow during summer. This study examined the sensitivity of late summer flows of 153 unregulated rivers over the period 1976-2003 to hydroclimatic influences by fitting regression models using simultaneous and lagged variables of precipitation and timing and magnitude of the snowmelt. To assess potential additional influences of long-term storage changes the residuals were tested for trends and serial correlation. A decrease in September flows across most of the region is broadly consistent with a decline in September precipitation. The most important control on August flows for all streamflow regimes is August precipitation. Lagged variables including July precipitation and the previous winter’s precipitation are also positively but more weakly related to August streamflow. Rain-dominated and hybrid catchments tended to have positive trends in their residuals in August, suggesting an increasing trend in groundwater storage. Snow-melt dominated catchments showed no tendency to trends but the runs test detected a substantial number of stations with nonrandom residuals. This regional study greatly improves the understanding of the hydroclimatic influences on extreme summer low flow in the region. Results suggest that (the less predictable) summer climate is a larger influence than previously assumed. They also help to identify where seasonal snow processes or long-term groundwater storage should be considered in model development, forecasting, and prediction of climate change impacts.
• Scheffler, C., Rosin, K., Weiler, M.
  Impacts of Mountain Pine Beetle on Peak Flow in the Fraser Basin in British Columbia
  2008 American Geophysical Union 2008 Fall Meeting, pages: H13D - 0957
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  Abstract

  Increasing winter temperature in combination with forest management practices are the main drivers for the Mountain Pine Beetle (MPB) epidemic in British Columbia (BC). The infestation of MPB has now turned into a major threat to the natural habitat of the province. The Fraser basin, the largest watershed in BC, is the most affected watershed with an infested forest area of 7.7 million hectares (88% of the watershed) [Redding and Pike 2007]. Forest cover is a key modifier of the watershed's peak flow regime. The peak flow generally increases when forest cover is reduced. Major parts of the Fraser basin have only a limited number of gauging stations (or are even ungauged). The goal of the project was to develop a hydrological model that can predict peak flow increases but does not rely on complex data inputs for its validation and calibration procedures. The model consists of two major components: climate input and runoff. The climate input component determines the mean annual snowmelt as well as the maximum rainfall based on long term climatic averages. This information is then used to determine the time and the capacity of the peak flow for every 3rd order watershed. The runoff component delineates hydrologic processes such as Hortonain Overland Flow, Saturation Overland Flow and Shallow Surface Flow. The model combines the two components and computes a map of peak flow contribution. A peak flow analysis has been carried out to validate the model results using available gauging stations in subcatchments. The validated model has been then applied to the entire watershed to analyze the impacts of MPB on peak flow in the Fraser basin. The presentation will show the conceptual presentation of the hydrological model. It will highlight the results of the peak flow analysis and show initial results of the application of the model. Cited Literature: Redding, T. and Pike, R (2007). Mountain Pine Beetle and Watershed Hydrology Workshop Summary, Streamline Watershed Management Bulletin 11(1), pp.22-24.
• Schelker, J., Burns, D. A., Weiler, M.
  Interactions of Stream Flow Dynamics and Mercury Variation During Snowmelt in an Adirondack Catchment
  2008 American Geophysical Union 2008 Fall Meeting, pages: B13C - 0453
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  Abstract

  Mercury transport in surface waters is strongly influenced by hydrological controls, especially by the state of saturation in catchment soils and by the hydrologic connectivity of uplands to riparian areas. In mountainous regions of the northeastern US, the period when saturation and connectivity is greatest is typically during spring snowmelt. We studied the transport of mercury during spring snowmelt in the Fishing Brook catchment, a headwater tributary with abundant riparian wetlands in the Hudson River basin of the Adirondack Mountains, New York. This stream has high concentrations of mercury, and values for unfiltered total Hg (UHg) ranged from 1.8 to 3.1 ng/L during the 2008 snowmelt. Dissolved organic carbon (DOC) is believed to be an important geochemical control on the transport of Hg through complexation, and DOC concentrations are strongly related to Hg concentrations in the upper Hudson basin. DOC concentrations were positively related to stream discharge at Fishing Brook during the 2008 snowmelt, and this relation showed counterclockwise hysteresis. Fewer snowmelt samples were analyzed for Hg than for DOC, however, UHg concentrations showed a strong positive nonlinear relation (r2 = 0.82) to discharge, consistent with the DOC - discharge pattern observed, and suggesting a common flushing effect. In contrast, unfiltered methyl Hg (UMeHg) concentrations decreased exponentially with discharge (r2 = 0.76) indicating supply-limited flushing during early spring. Hydrological modeling results using TOPMODEL with snowmelt data from 2007 indicated that UHg concentrations were strongly related to simulated saturated area in the catchment. When this modeled relation was then applied to Hg data from 2008, good agreement between modeled and measured UHg concentrations was obtained. These results indicate that as the water table rises to the surface during snowmelt, DOC and Hg are simultaneously flushed to surface waters, whereas a supply limitation of MeHg results in diminishing concentrations as the snowmelt proceeds. Thus snowmelt can be assumed as a main process to form sufficient supply of inorganic Hg and DOC to the hot spots of methylation.
• Trubilowicz, J., Weiler, M.
  Motes for forest hydrology – is the time right?
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-04904
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  Abstract

  Low cost, low power wireless sensors (motes) promise to revolutionize environmental data collection, but are they currently refined enough for widespread use by hydrologists? We investigated their viability as a replacement for traditional data collection techniques in a 7 ha forested watershed in South-western British Columbia. The watershed included 3 V-notch weirs and 41 instrument clusters measuring air and soil temperature, humidity, rainfall or throughfall, soil moisture content, and groundwater head. Overland flow occurrence was measured at 16 locations. The foundation of each cluster was a data box containing a MDA300 data acquisition board and a MICA2 processor board from Crossbow Technologies, Inc that allowed for short range wireless data collection. The 41 motes each recorded data every 15 minutes from July, 2006 to April, 2007. In addition to reporting on the reliability of the motes and sensors during the 10 months deployment, the high spatial and temporal resolution data collected by this experiment gave the opportunity to investigate if it is possible to oversample a watershed. We created subsets of different sample sizes using soil moisture and throughfall data. We selected four hydrological events and three entire months from the complete data set and created ensembles of 100 different realizations each of 5, 10, and 20 randomly selected sampling points. Comparing the root mean squared error (RMSE) between each realization and the value for the full data set enabled us to determine if increasing the sample size produced diminishing returns. There were also significant differences in prediction error for both soil moisture and throughfall at times of differing hydrologic activity. This analysis also provides further support for the theories of changing moisture states of soil moisture and threshold values for throughfall.
• Lange, J., Gunkel, A., Shadeed, S., Fischer, C., Krier, R., Morin, E., Grodek, T., Menzel, L.
  New insights into the variability of water resources in the Jordan River Catchment
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-06210
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  Abstract

  In the Middle East the temporal and spatial variability of rainfall is pronounced, which has always led to water scarcity and severe drought events. This fact puts a challenge on assessments of available water resources, since those are normally based on long term averages. In this study we focus on the variability of rainfall and aim to investigate how this signal is amplified in the hydrological cycle in the arid and semi arid parts of the Lower Jordan River basin. Moreover we show how different rainfall characteristics affect dominating runoff generation processes. We use volume scanning rainfall radar to provide highly resoluted, 5 minute precipitation data for entire seasons and use them as input to process-based hydrological modelling. To include the full range of present rainfall variability one average and two extreme seasons are studied. For calibration purposes the seasonal radar data set is separated into events up to several days long. These events are analysed for spatial characteristics, intensity distribution and prevailing direction of the moving rainfall cells. The hydrological models (TRAIN-ZIN) are first applied to two focus catchments. The 320 km2 Faria catchment is located in the northeastern part of the West Bank. Topographic relief is accentuated resulting in a strong rainfall gradient. Simulations show that the water balance of single events strongly depends on rainfall characteristics which affect the dominating runoff generation processes (infiltration- versus saturation excess runoff). Seasonal simulations confirm that relatively small changes in rainfall may lead to considerable changes in generated runoff and percolating soil water available for groundwater recharge. The 170 km2 Harod catchment, situated 25 km south of Lake Tiberias, is relatively flat and heavily used by agriculture. Also here rainfall characteristics dominate runoff generation processes and alter hydrological effects of landuse changes (e.g. urbanization). While during a wet season a series of runoff events was generated, the river remained entirely dry during the drought season of 1998/99. Simulated evapotranspiration and soil water percolation provides interesting insights into green and blue water variability. In a final step focus catchment knowledge is extrapolated to simulations of the entire Lower Jordan River Basin which serve as guidelines for regional water management.
• Weiler, M., Jost, G., Floyd, W., Varhola, A.
  Sensing dynamics of snow – vegetation interaction
  2008 American Geophysical Union 2008 Fall Meeting, pages: C34A - 02
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  Abstract

  Snow accumulation and melt governs the hydrology in many parts of the world. Vegetation can further alter these processes. While sub-disciplines in hydrology, ecology and meteorology have been researching the influence of vegetation cover and vegetation structure on (i) water storage as snow and (ii) water release during snowmelt for a long time, experimental techniques have been weak at addressing two important aspects of these two processes: their spatial variability and temporal dynamics. We have developed new sensors and low-cost sensor packages to observe the dynamics of snow processes in the vegetation cover at an adequate spatial scale and a number of sample locations. Complemented by a better description of the vegetation structure derived from LiDAR and other remote sensing methods, the collected data allows exploring and analyzing new aspects of the role of vegetation in the dynamics of the storage and release process. In this contribution we introduce experimental design and deployed sensors, present first results on the impact of vegetation cover and structure on snow processes at individual sites and outline the potential to address space-time dynamics over larger areas.
• Kuells, C., Wenninger, J., Klaus, J., Huxol, S., Moritz, K., Zabori, J.
  Significant trends, underlying processes and indicators - the validation of hydrological change
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-11508
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  Abstract

  Changes in hydrological processes are often complex and involve modifications in several components of the water cycle at different scales in space and in time. While statistical methods provide an exploratory approach, the plausibility of significant changes in the hydrological system depends on whether underlying processes can be identified and associated with such trends as well. For a meso-scale research basin, the Dreisam river basin (300 skm, Germany), a combined approach for the detection and validation of changes in hydrological processes has been tested. The combined approach involves ensemble time series analysis for the detection of trends by nonparametric Mann-Kendall tests including detrending and correction procedures for auto-correlation. Time series analysis was carried out on ensembles of water cycle components (precipitation, temperature, absolute atmospheric moisture, derived potential evaporation, runoff and its isotopic composition) in order to detect seasonal, scale and altitude dependent, synchronized changes in respective balances, processes and regimes. Process-oriented, physically-based modeling was then carried out in order to test the validity and plausibility of observed significant changes by corresponding sensitivity analysis. The results of hydrological modeling were re-analyzed by statistical methods in order to ascertain the significance of modeled results compared to original time series. Finally, the consistency of observed process changes with stable isotope signatures was ascertained. The combined approach yielded significant internal changes in snow-melt and recharge mechanisms as well as shifts in runoff regimes resulting from increased ambient temperature.
• Smith, R. S., Moore, R. D., Weiler, M.
  Spatio-temporal Variability in Midwinter Snowmelt Generated by Ground Heat Flux: Implications for Catchment Hydrology
  2008 American Geophysical Union 2008 Fall Meeting, pages: H21L - 05
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  Abstract

  Ground heat flux is commonly ignored in the modelling of snowpack energy exchanges and snowmelt runoff due to its perceived insignificance relative to other energy sources. Snowmelt at the base of a snowpack was continuously measured during the winters of 2006/07 and 2007/08 with 4 m2 lysimeters at six sites within a 3.5 km2 continental, mountainous catchment in southeast British Columbia. Soil wetness and soil, air, and snow temperatures were also continuously measured at each site. During the 2006/07 winter season, accumulated snowmelt during a three month midwinter period with sub- zero air temperatures ranged from 11 to 107 mm, comprising 3 to 36 % as much as the annual peak snow water accumulation. Daily snowmelt regularly exceeded 1 mm at several sites while daily maximum air temperatures were well below 0°C suggesting that ground heat flux generated the midwinter snowmelt (i.e. ground melt). Temporal variability of melt was strongly associated with air temperature, even at sub-zero temperatures. Spatial variability of melt was strongly associated with soil wetness, and wetness levels at wetter sites were maintained or increased through ground melt inputs. During the 2007/08 midwinter period, accumulated ground melt did not exceed 10 mm due to extensive soil freezing prior to snowpack development. The results suggest that a positive feedback response loop exists between soil wetness, ground heat flux, and ground melt due to the association between soil thermal conductivity and soil wetness. Pre-winter soil wetness and soil temperature, and winter meteorology influence the amount of midwinter ground melt because they control the relative amounts of ground heat flux that are used for melt, soil warming, or snowpack heat conduction. Pre-winter soil hydro-thermal dynamics and midwinter ground melt might be important controls on the spatial pattern of winter/spring catchment wetness and subsequent runoff response if antecedent soil conditions and ground melt inputs are spatially organized. A conceptual model is presented that describes the processes controlling midwinter ground melt
• Kuells, C., Dahan, O., Benito, G.
  TheWADE experience - twinning hydrological research and IWRM in European and Southern African drylands
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-11367
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  Abstract

  As part of the EU Water Initiative and the EU Basin Twinning Programme, the implementation of IWRM in arid and semi-arid basins has been supported through several basic and applied research projects (e.g. WADE, GABARDINE, TWINLATIN projects). One of these, the WADE Project, has studied specific aspects of water resources assessment from floods in arid basins in northern and southern countries and has examined the socio-economic ramifications for the southern hemisphere partners. The experience gained from this project indicates that the objectives, methodology and instruments of IWRM need to be carefully re-framed to the specific conditions encountered in such environments. These specific conditions vary considerably between north and south, and IWRM is often interpreted differently in developed countries and developing countries. In drylands, where the resources are minimal and the relatively needs are high, ephemeral river basins surface runoff and indirect (flood) recharge of alluvial aquifers (influenced by vegetation cover and associated land management) dominate the generation of water resources and constitute important local elements for water supply and therefore need to be encompassed into IWRM planning. Institutional and sectoral integration that takes into account cultural heterogeneities and historic conflicts should precede technical knowledge related to available water resources in order of importance in the process of IWRM planning. Instruments for the efficient communication between, and participation of, stakeholders with extremely different economic productivity, with strongly different degrees of social aggregation, or with an unbalanced political representation, need to be developed. The WADE Project has provided experimental data and a detailed understanding of hydrological processes for the assessment, management and use of alluvial aquifers. The development of common hydrological understanding based on field data and a common research experience was a central element of WADE.
• Anderson, A., Weiler, M.
  Tracer based investigation of a hillslope subsurface flow network
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-04746
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  Abstract

  We combined tracer experiments under natural and steady state conditions with dye staining techniques to investigate the behaviour and physical characteristics of a hillslope subsurface flow network in an experimental watershed on Vancouver Island, Canada. Our objectives were: 1) to determine the relationship between lateral flow velocities and hillslope length, steady state flow rate, rainfall intensity, total rainfall amount, and antecedent condition, and 2) to determine if the development of preferential flow features is influenced by topographical factors such as slope and contributing area. We calculated average flow velocities by fitting transport models to tracer breakthrough data. The flow velocities were most closely related to the rainfall intensity and changes in flow velocity were large compared to the small changes in flow rates through the hillslope. The flow velocities were also affected by boundary conditions and slope length (an order of magnitude difference between 12 m and 30 m), which highlighted the importance of a representative volume used in the experiment. The dye staining and excavation revealed 1) evidence of past subsurface erosion and deposition of soil and organic material, and 2) a positive correlation between surface topography contributing area and the size and connectedness of preferential features. This supports the hypothesis that contributing area is related to network properties because the amount of subsurface flow influences the enlargement and preservation of the preferential features and is generally proportional to the contributing area. The experiments successfully applied methods commonly used for smaller soil-core experiments to a larger hillslope scale. The presented relationships of hillslope behaviour and physical characteristics could help to refine models of runoff, slope stability, and solute transport and may have implications for land use.
• Bachmair, S., Weiler, M., Nützmann, G.
  Tracer experiments and simulations on the effect of land use on preferential flow
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-09235
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  Abstract

  Despite intensive research on macropore flow, simulating flow processes in macroporous soil remains challenging due to the various and complex controlling factors. One of these controlling factors is land use and land cover, altering the soil surface and permeability of the topsoil as well as the type of generated macropore network (worm burrows, root channels, shrinking cracks and interaggregate voids). The objective of this study is to investigate the effects of different land use and land cover on the formation of soil structure and significance of macropore flow and to test whether the INfiltration–INitiation–INteraction Model (IN3M) is capable to predict water flow in macroporous soil under different land use and land cover. IN3M is a physically based, dual permeability model developed for grassland soils mainly containing earthworm channels, which has shown good agreement with field observations. In order to evaluate the predictive power of the model for different land use types, dye tracer experiments with Brilliant Blue FCF were conducted on 5 sites, each one exhibiting similar soil textural characteristics but differences in land use and management practices (grassland – farmland, tilled and untilled – forest). Each 1.2x1.5 m experimental plot was partitioned into three subplots, which were sprinkled with an intensity of 15mm h-1 and a total infiltration amount of 20, 40, and 60 mm, respectively, to explore the effects of different infiltration amounts on macropore flow processes. During the irrigation, water content changes were continuously measured using time domain reflectometry, with 16 probes vertically installed into the profile at different depths. After the experiments vertical and horizontal soil sections were excavated and photographed. The images were processed using digital image analysis and the resulting dye pattern classified into distinct flow type categories. The flow types were distinctively different among the sites and could be related to the different biological and physical agents altering the macropore structure. Simulations with IN3M and a multi-criteria validation based on soil water content changes and classified dye patterns revealed certain strengths of the model to capture the observed flow and transport processes in soils dominated by worm burrows, but also revealed weaknesses for other structural features in particular in forests and tilled farmland.
• Stahl, K., Hisdal, H., Tallaksen, L.M., van Lanen, H.A.J., Hannaford, J., Sauquet, E., Demuth, S.
  Trends in low flows and droughts in small undisturbed rivers across Europe
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-04801
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  Abstract

  In the recent past, several notably hot and dry summers have had major societal impacts in Europe, which has focused interest on the detection and attribution of temporal trends and spatial patterns in the occurrence and severity of low flows and hydrological droughts. Several recent studies have investigated such trends at a local or national level and results vary considerably, which to some extent is due to the use of different time periods and methods. In a collaborative effort initiated by UNESCO through the FRIEND research programme, streamflow data are brought together from small undisturbed catchments in Scandinavia, the UK, Germany, the Czech Republic, Slovakia, France, and Spain to investigate regional patterns of trends in streamflow drought across Europe. The UNESCO-IHP FRIEND European Water Archive Archive has been updated to the year 2005 to include the recent severe droughts and was supplemented by national data for this study. The results will provide opportunity to be compared (i) to an earlier study that was based on data of an earlier version of the archive for the periods of 1930-1990 and 1962-1990 and (ii) to several recent trend studies on large rivers, which are potentially more prone to direct human influences on low flows. Preliminary results of trend analyses are presented for a range of low flow and drought indices, including seasonal minimum flows, drought duration, and drought deficit below different thresholds, based on the Mann-Kendall test and a randomization test for determination of field significance.
• Shadeed, S., Lange, J., Gunkel, A.
  Up To Date Hydrological Modeling in Arid and Semi-Arid Catchment, the Case of Faria Catchment, West Bank, Palestine
  2008 EGU General Assembly 2008, volume: 10, pages: EGU2008 - A-07023
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  Abstract

  Understanding runoff generation mechanisms is the most basic challenge to hydrologists to enhance the evaluation and quantification of water resources in arid and semiarid catchments. Faria catchment, located in the northeastern part of the West Bank, Palestine, is one of these arid to semi-arid catchments where diminutive work has been carried out concerning hydrological modeling. This paper deals with the modeling of rainfall-runoff processes in the Faria catchment under limited hydro-meteorological and spatial data. The goal has been to obtain reliable estimates of naturally available surface water resources. For this purpose, an up to date process-oriented and physically-based distributed rainfall-runoff model (coupled TRAIN-ZIN) has been applied. Three years of monitoring rainfall and runoff combined with thorough field campaigns (e.g. measuring infiltration rates) are considered to be the cornerstones for the success of this study. The coupled TRAIN-ZIN model is calibrated and validated using single rainstorm events. After successful calibration and validation continuous simulations of the entire rainy seasons 2004/05, 2005/06 and 2006/07 from October to April were achieved. This facilitated accurate assessments of seasonal water balances in the entire Faria catchment Despite of difficulties, limitations and uncertainties associated with obtaining observations and measured parameters; this study ended-up with optimistic results for the simulation of single events and entire seasons in continuous mode.. The obtained results are good enough to assume the applicability of the coupled TRAIN-ZIN model to arid and semi-arid catchments. This gives confidence towards applying this model to the other catchments in the West Bank in order to evaluate the naturally available surface water. Such evaluation can be utilized in the development of best management practices to be adopted to manage the scarce water resources in the region, under current and future global changes conditions.
• Anderson, A., Weiler, M.
  Watertable response characteristics in hillslopes dominated by preferential flow
  2008 American Geophysical Union 2008 Fall Meeting, pages: H24C - 04
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  Abstract

  Characterizing areas in a watershed based on the water table behaviour should help us to better understand and predict internal watershed processes. Areas with a similar response pattern could also be used to apply semi-distributed models, especially in watersheds with limited data. If lateral preferential flow is a dominating runoff process, the water table response typically shows a distinct hydraulically-limited pattern. This response is characterised by a capping of the rising water table when the lateral preferential flow features are activated and subsurface flow still increases. At our forested study site on the west coast of British Columbia, Canada, we expected that this response would be related to the contributing area since nearby hillslope excavations showed that the development of preferential flow network was positively correlated to the contributing area. We mapped the watershed into three predetermined zones and installed 25 piezometers to sample the water table dynamics. The objectives were 1) to characterize the water table – runoff relationship, 2) to prove preferential flow by observable characteristics, and 3) to test the feasibility of identifying areas within a watershed that are dominated by lateral preferential flow. We could identify the extreme water table responses; however, the watershed areas were not well defined. In addition, there was no strong relationship between the hydraulically-limited response and observable watershed characteristics. Although areas might still be useful for grouping the hillslope processes, the water table response measured with piezometers may not be an appropriate indicator for mapping the watershed into areas with runoff dominated by lateral preferential flow.

2007

• Lange, J., Grégoire, S., Hartmann, D.
  Abfluss von versiegelten Flächen: Prozessuntersuchungen und hydrologische Modellierung
  2007 Analyse und Modelling der Niederschlags-Abfluss-Prozesse. Bewährte Techniken und neue Ansätze Tagungsband zum 80.Geburtstag von Prof. Dr.-Ing. Siegfried Dyck und des 40-jährigen Bestehens der Dresdner Schule der Hydrologie am 05./06. Okt. 2006, pages: 445 - 446
• Carver, Martin, Weiler, Markus, Utzig, Gregory, Sulyma, Randy
  Hydrologic Risk Assessment: Preliminary Modelling Results
  2007 Mountain Pine Beetle and Watershed Hydrology Workshop: Preliminary Results of Research from BC, Alberta and Colorado
• Martin Carver, Markus Weiler, Gregory Utzig, Randy Sulyma
  Hydrologic Risk Assessment: Preliminary Modelling Results
  2007 Mountain Pine Beetle and Watershed Hydrology Workshop: Preliminary Results of Research from BC, Alberta and Colorado
• Külls, Christoph
  Identifying dominant processes of groundwater recharge using characteristical patterns of CFCs and SF6 in conjunction with analyses of stable isotopes.
  2007 IUGG, XXIV 2007
• Kuells, C., Fersch, B.
  Interaction between riparian phreatophytes, alluvial aquifers and channel processes
  2007 EGU General Assembly 2007, volume: 9, pages: EGU2007 - A-10850
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  Abstract

  The interplay of vegetation patterns, alluvial aquifer water balances and channel processes during floods was investigated in a large-scale semi-arid basin with crystaline basement (Buffelsrivier/SA). The evaporation from phreatophytic vegetation in alluvial aquifers was desribed using an adaptive individual-based model of tree proliferation coupled to numerical surface flow and groundwater models. The application of this individual-based model approach revealed the adaptive behaviour of the ecohydrological system and allowed a determination of regional actual evaporation. Only specific patterns of tree distribution and density, resulting from an adaptive process of proliferation and dying, stabilized the groundwater flow system close to the range of observed groundwater levels. While groundwater depth and lateral flow control the distribution of tamarisk and acacia vegetation, the phreatophytes regulate water levels and the flow system. Indirect recharge from floods responds to the available storage resulting from such interaction. The opposition of these processes constitutes an adaptive ecohydrological system that could not be modelled adequately in previous investigation steps using non-adaptive approaches.
• Lange, J., Schütz, T., Gunkel, A., Grodek, T., Steinmann, A., Menzel, L.
  Representing dryland runoff generation processes in hydrological models: experiences from a small mediterranean catchment.
  2007 EGU General Assembly 2007, volume: 9, pages: EGU2007 - A-05489
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  Abstract

  We applied a coupled SVAT / hydrological modelling framework to describe ongoing hydrological processes in a small dryland catchment. The 1.1 km2 first order study catchment is located in the foothills of the Judean Mountains close to the city of Modiin, Israel. Limestones and dolomites alternate with less permeable chalks and marls. They are partly covered by calcrete crusts and form only shallow Rendzina soils. Mean annual rainfall totals to 540 mm and falls in the rainy season between October and April. Using 16 m2 grid cells the SVAT model TRAIN was used to simulate daily vertical water fluxes that dominate the long term water balance with a special focus on evapotranspiration. On 4 m2 grid cells the hydrological model ZIN simulated runoff generation and lateral water fluxes with a temporal resolution of one minute. On rocky hillslopes with only patchy soil cover the generation of Hortonian- and saturation excess overland flow was described by soil storages representing discontinuous soil pockets. These were filled by rainfall following field-derived infiltration characteristics. They were emptied by actual evapotranspiration simulated by TRAIN and by a dynamical deep drainage depending on calculated soil moisture contents . Runon processes at the slope base were described by colluvial storages accepting hillslope runoff from upslope areas. They comprised 14.7% of the catchment. Only when these storages in the valley bottom were entirely saturated, hillslopes were connected to the channel and finally contributed runoff. The coupled models were parameterized using field information on soil characteristics, infiltration rates and catchment morphology, no model calibration was performed. To check the models, three months (January to March) of continuous (5 min) readings of soil moisture, hillslope and catchment runoff were compared to continuous model simulations. On rocky upslope areas soil moisture dynamics were perfectly reproduced, the same was true for the timing of the onset of slope runoff. At the colluvial base the models underestimated the amplitude of observed soil moisture changes. This was mainly attributed to influences of ponded runoff water observed at the location of soil moisture measurement. Considering the fact that the models were non-calibrated, the observed fits between simulated and observed runoff were promising both at the hillslope station and at the catchment outlet. During the entire three months there was little evidence for Hortonian runoff. While the three month volume of simulated runoff compared nicely to the measured total, differences in single events were mainly attributed to uncertainties in exactly defining the location and vertical extent of runoff accepting colluvial storages.
• Lange, J., Hänsler, A.
  Stream temperature as a tracer to document runoff generation at different moisture states
  2007 EGU General Assembly 2007, volume: 9, pages: EGU2007 - A-05484
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  Abstract

  The 1.3 km2 Engebächle catchment is located in the Black Forest Mountains, southwest Germany. The catchment is characterized by 1100 mm mean annual precipitation, steep slopes and crystalline rocks which are overlain by periglacial drift covers. During two different events in summer 2005 stream temperature measurements were used to illustrate runoff generation processes at different moisture states. Temperature sensors were placed immediately up-, downstream and within an extended saturated area at the upstream beginning of a 1.2 km channel reach. Down the reach these were followed by additional sensors and finally by a combined conductivity-temperature logger at the runoff gauge. The first event - a 25 min thunderstorm - occurred at dry preconditions and minimum baseflow, while the second 11h storm hit a wet catchment at the end of summer. Immediately before the first event stream temperature was generally high. During the event it dropped sharply by about 7 C reaching a minimum value inside the saturated area. Comparing this minimum with values in the stream channel immediately up- and downstream the saturated area, a maximum contribution of about 60% saturated area runoff was determined. During the second event temperature differences among the sensors were non significant suggesting a more uniform runoff generation. During both events drops in stream temperature were used for a two component hydrograph separation separating cold event rainfall from a relatively warm pre-event baseflow component. Rainfall temperature was approximated by air temperature and a cooling of the pre-event component by applying an energy balance model. Simultaneous hydrograph separation using conductivity served as plausibility control. Here baseflow of constantly high conductivity was assumed to be diluted by less mineralized rainfall. The separation results obtained by conductivity fell inside the uncertainty range of the temperature based calculation. At dry conditions (event 1) about two thirds of the quick flow (direct runoff) were found to be event water. The temperature based separation pointed to surficial runoff generation and flow paths. Overland flow from forest roads was considered as one probable runoff source, the other was saturated area runoff, which could directly be quantified at one location. At wet conditions (event 2) a similar rain amount produced only 36% of event water in quick flow. The much larger fraction of pre-event water originated from reservoirs only active at higher moisture states which was also apparent in a delayed flow recession.

2006

• Demuth, S., Gustard, A., Planos, E., Scatena, F., Servat, E.
  Climate Variability and Change - Hydrological Impact
  2006 Vth International FRIEND World Conference, volume: 308, page: 703 pp
• Birkel, Ch., Demuth, S.
  Drought in Costa Rica - temporal and spatial behaviour, trends and the relationship to atmospheric circulation pattern
  2006 Climate Variability an Change - Hydrological Impact - Vth International FRIEND World Conference, pages: 338 - 343
• Lange, J., Hänsler, A., Hugenschmidt, C.
  Hydrologische Prozessforschung bei Niedrigwasser in bewaldeten Einzugsgebieten - Einblick in die Funktionsweise bei extremen Dürreereignissen
  2006 Tag der Hydrologie, pages: 133 - 142
• Uhlenbrook, S., Wenninger, J.
  Identification of flow pathways along hillslopes using electrical resistivity tomography (ERT)
  2006 7th IAHS Scientific Assembly, pages: 15 - 20
• Lange, J., Hänsler, A., Hugenschmidt, C.
  Investigating runoff generation at low flow conditions – how valuable are tracer methods?
  2006 EGU General Assembly 2006, volume: 8, pages: EGU06 - A-08888
  » show abstract« hide abstract
  Abstract

  The role of antecedent conditions for the catchment response is widely acknowledged. However, most studies concentrate on flood generation at relatively high moisture states excluding process investigations at low flow conditions. To cover a larger range of hydrological preconditions - especially at low flow - we conducted extensive field measurements in a steep 1.3 km2 forest catchment in southern Germany during a 4 month summer period. These included (a) continuous soil moisture measurements; (b) continuous stream flow measurements of runoff, temperature, conductivity and turbidity; (c) continuous riparian zone measurements of groundwater levels, temperature and conductivity; and (d) weekly sampling for tracers (major ions and O-18) in the stream and neighboring hillslope springs. Measurements started during a five week drought in May/June (period of intense forest growth) to continue with more rainfall up to the end. Runoff recession analysis pointed to a gradual filling of hydrological reservoirs. These hydrological reservoirs were assumed to be located in periglacial drift covers on hillslopes, since riparian zones were limited and measurements did not suggest significant runoff contributions. Hillslope soil moisture measurements supported this theory since they showed a gradual wetting of deeper soil layers. Still hydrometry was not enough to provide a final proof for runoff generation processes relevant at the catchment scale. Tracers provided the missing information in a two-fold way. First, classic two-component hydrograph separations (using both continuous temperature and conductivity readings) showed a gradually rising pre-event component in measured runoff events. Second, natural tracers provided the link between springs and stream to identify source areas of runoff. Due to metamorphic, crystalline lithology chloride enrichment by the influence of transpiration served as tracer to assign different springs to contributing reservoirs and to document their relative importance for stream flow generation. While chloride concentrations of most springs corresponded to long term values of transpiration and groundwater recharge, two springs at upper hillslope positions were significantly elevated in chloride. Hence a three-component end member mixing analysis using chloride and O-18 could be used to show the limited importance of the root zone in summer streamflow. Our data rather suggested that retarded flow recession and enhanced pre-event contributions towards the end of summer were not directly linked to a filling of the root zone but originated from deeper reservoirs. For this distinction silica was less applicable, because silica concentrations seemed to be dominated by differences in longer term residence times rather than by a functional distinction between contributing hillslope reservoirs.
• Lange, J., Leistert, H., Schwartz, U.
  Process-based simulation of channel transmission losses
  2006 EGU General Assembly 2006, volume: 8, pages: EGU06 - A-08934
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  Abstract

  During flood events in ephemeral dryland streams various processes (e.g. erosion and deposition of sealing fine material layers, losses into flooded overbank areas) are active, constantly modifying the intensity and amount of channel transmission losses. These processes are hardly measurable and highly variable in time and space, making the accurate quantification of loss volumes during real flood events difficult, especially at larger scales. Therefore we tried to include process and field knowledge into a flood routing scheme to realistically simulate channel transmission losses during real flood events. Infiltration rates were described by the Newton-Raphson iteration of the Green-Ampt model accounting for changes in initial moisture content by an antecent moisture index. Overbank losses by infiltration and evaporation were included by a linear storage concept. To account for the sealing effect of deposited silt layers, channel infiltration reached its maximum rate only when the flow velocity exceeded a specified critical velocity. Aerial photographs, topographical maps and TDR-measurements in the channel alluvium during flood events served to parameterize the model, still calibration was required. The model was applied to two channel reaches in Wadi Zin, the Negev Desert, Israel, 5.5 and 76 km long. Since events without lateral inflow were chosen, measured hydrographs at the downstream end of the reaches could be used for model calibration and independent model checks. In the 5.5 km reach the model was calibrated for the largest (100 m3 s-1) event and applied to small events (8, 14 m3 s-1) with the same parameter set resulting in close model fits. However, re-calibration was necessary when the model was applied to the 76 km reach, which was attributed to different channel characteristics rather than to scale effects.
• Konz, M., Braun, L.N., Uhlenbrook, S., Demuth, S., Shresta, A.
  Regionalisation of a process-oriented distributed catchment model for highly glacierized Nepalese head watersheds
  2006 Climate Variability and Change - Hydrological Impact - Vth International FRIEND World Conference, pages: 454 - 459
• Bracken, P., Wachtler, A., Panesar, A., Lange, Jörg
  The road not taken: how traditional excreta and greywater management may point the way to a sustainable future
  2006 1st IWA International Symposium on Water and Wastewater Technologies in Ancient Civilisations, pages: 145 - 154
• Gunkel, A., Kuells, Ch.
  Towards agent-based modelling of stakeholder behaviour - a pilot study on drought vulnerability of decentral water supply in NE Brazil
  2006 Proceedings of the iEMSs Third Biennial Meeting, "Summit on Environmental Modelling and Software"
• Königer, P., Schwientek, M., Uhlenbrook, S., Leibundgut, Ch., Krause, W. J.
  Tritiumbilanz im Wesergebiet durch Koppelung von TRIBIL mit dem hydrologischen Modell TACD
  2006 15. Chemisches Kolloquium, volume: 4/2006, pages: 70 - 80

Other publications

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2019

• Steinbrich, A., Leistert, H., Weiler, M.
  Erarbeitung von Grundlagen für die landesweite Abschätzung der Vulnerabilität von Grundwasser gegenüber Stoffeinträgen durch Sickerwasser und eines flächendetaillierten Grundwasserneubildungs-Index (GwN-I)
  , page: 67, 2019
• Kirn, L., Weiler, M.
  Hochwasserentstehungsgebiete
  , page: 56, 2019
• Haag, I., Aigne, D., Krumm, J., Antonetti, M., Regenauer, J., Weiler, M., Steinbrich, A.
  LARSIM-Weiterentwicklungen für Starkregenereignisse
  , page: 184, 2019
• Professur für Hydrologie, Professur für Humangeographie
  Wasserhaushalt siedlungsgeprägter Gewässer (WaSiG): Planungsinstrumente und Bewirtschaftungskonzepte. Abschlussbericht
  , volume: 98, page: 56, 2019

2018

• Kirn, L., Ries, F., Weiler, M.
  Phosphor- und Nitrataustrag bei simuliertem Starkregen an Hängen in Baden-Württemberg
  , page: 62, 2018
• Zieger, F., Herbstritt, B., Weiler, M.
  Physikalisch-Chemisches Gewässermonitoring im Freiburger Stadtgebiet
  , page: 156, 2018
• Ries, F., Kirn, L., Weiler, M.
  Validierung von Oberflächenabflüssen nach Starkregen an Hängen in Baden-Württemberg.
  , page: 91, 2018

2017

• Gunkel, Anne
  Performance of hydrological models in semi-arid areas and radar-based climate change impact assessment
  , 2017

2016

• Ries, Fabian
  Hydrological modelling of catchment scale runoff-recharge processes under a strong, semi-arid, climatic gradient
  , 2016
• Gaj, Marcel
  Recharge estimation in a (semi-) arid environment using soil water balance, stable isotopes and modeling approaches
  , 2016
• Schwerdtfeger, Julia
  Spatial and temporal dynamics of hydrological processes in the Pantanal wetland, Brazil
  , 2016
• Volkmann, Till H. M.
  Spatial and temporal variability of stable water isotopes along the soil-plant-atmosphere continuum
  , 2016
• Stahl, K., Weiler, M., Kohn, I., Freudiger, D., Seibert, J., Vis, M., Gerlinger, K., Böhm, M.
  The snow and galcier melt components of streamflow of the river Rhine and its tributaries considering the influence of climate change - Synthesis report.
  , 2016

2015

• Blauhut, Veit
  Drought Risk and Vulnerability on a pan-European scale
  , 2015
• Joseph, Jobin
  Effects of Drought on dynamics and interactions of water and carbon cycles in a plant-soil-athmosphere continuum
  , 2015
• Gimbel, Katharina
  Influence of Artificial Drought on Soil Hydrology of Temperate Forest Ecosystems
  , 2015
• Sprenger, Matthias
  Spatio-temporal variation of vadose zone transit times
  , 2015
• Stoewer, Myriam
  Vulnerability assessment of nitrate leaching on the regional scale using isotope techniques
  , 2015

2014

• Rühle, Franziska
  Dynamic hydrological fluxes and biogeochemical gradientsat the interface between the unsaturated and saturated zone
  , 2014
• Stölzle, Michael
  Klimasensitivität und Vulnerabilität von Fließgewässern in Zusammenhang mit Niedrigwasserabflüssen in Baden-Württemberg
  , 2014
• Garvelmann, Jakob
  Observations of the spatial and temporal variability of snowmelt energetics and runoff generation during rain-on-snow in a forested mid-latitude mountain environment
  , 2014
• Farlin, Julien
  On the delineation of spring recharge area using pesticides, recession analysisand groundwater dating techniques in a fractured-rock aquifer
  , 2014

2013

• Davila, Pablo
  Age Dating of Water using SF5CF3 and SF6
  , 2013
• Gaßmann, Matthias
  Environmental fate modelling of agrochemicals and their transformationproducts at catchment scale
  , 2013
• Hartmann, Andreas
  Modelling karst hydrology and hydrochemistry in different scales and climates considering prediction uncertainty
  , 2013

2012

• Bachmair, S.
  Experimental investigation of hillslope hydrological dynamics
  , 2012
• Leistert, H., Weiler, M.
  Gewässerbeschattung
  Umweltministerium Baden-Württemberg, 2012
• Brena, Augustin
  Past and future changes in forest ecosystems: Connections between watersheds characteristics, forests and low flows
  Freiburg, 2012

2011

• Hünninger, Marko
  Development of experimental, monitoring, and mathematical methods to quantify water fluxes and transport in heterogeneous aquifer system models
  , 2011
• Michel, Werner
  Numerische Modellierung der Interaktionen zwischen Oberflächengewässern unddem Grundwasser mit Hilfe von geohydraulischen, isotopenhydrologischen undhydrochemischen Untersuchungen
  , 2011
• Schütz, Tobias
  Solute transport in constructed wetlands: tracer tools and transient storage modelling
  , 2011

2010

• Steinmann, A.
  Runoff generation in Mediterranean areas
  , 2010