TY - JOUR A1 - Bronstert, Axel A1 - Engel, H. T1 - Veränderung der Abflüsse JF - Warnsignal Klima - genug Wasser für alle? : wissenschaftliche Fakten Y1 - 2005 SN - 978-3-9809668-0-1 SP - 175 EP - 181 PB - Wissenschaftliche Auswertungen CY - Hamburg ER - TY - JOUR A1 - Xenopoulos, M. A. A1 - Lodge, D. M. A1 - Alcamo, Joseph A1 - Marker, Michael A1 - Schulze, K. A1 - Van Vuuren, Detlef P. T1 - Scenarios of freshwater fish extinctions from climate change and water withdrawal N2 - Reductions in river discharge (water availability) like those from climate change or increased water withdrawal, reduce freshwater biodiversity. We combined two scenarios from the Intergovernmental Panel for Climate Change with a global hydrological model to build global scenarios of future losses in river discharge from climate change and increased water withdrawal. Applying these results to known relationships between fish species and discharge, we build scenarios of losses (at equilibrium) of riverine fish richness. In rivers with reduced discharge, up to 75% (quartile range 4-22%) of local fish biodiversity would be headed toward extinction by 2070 because of combined changes in climate and water consumption. Fish loss in the scenarios fell disproportionately on poor countries. Reductions in water consumption could prevent many of the extinctions in these scenarios Y1 - 2005 SN - 1354-1013 ER - TY - JOUR A1 - Belina, Bernd T1 - Anglophones : If you want us to understand you, you will have to speak understandably! Y1 - 2005 SN - 0066-4812 ER - TY - JOUR A1 - Zehe, Erwin A1 - Becker, Rolf A1 - Bardossy, Andras A1 - Plate, Erich T1 - Uncertainty of simulated catchment runoff response in the presence of threshold processes : role of initial soil moisture and precipitation N2 - This paper examines the effect of spatially variable initial soil moisture and spatially variable precipitation on predictive uncertainty of simulated catchment scale runoff response in the presence of threshold processes. The underlying philosophy is to use a physically based hydrological model named CATFLOW as a virtual landscape, assuming perfect knowledge of the processes. The model, which in particular conceptualizes preferential flow as threshold process, was developed based on intensive process and parameter studies and has already been successfully applied to simulate flow and transport at different scales and catchments. Study area is the intensively investigated Weiherbach catchment. Numerous replicas of spatially variable initial soil moisture or spatially variable precipitation with the same geostatistical properties are conditioned to observed soil moisture and precipitation data and serve as initial and boundary conditions for the model during repeated simulations. The effect of spatially soil moisture on modeling catchment runoff response was found to depend strongly on average saturation of the catchment. Different realizations of initial soil moisture yielded strongly different hydrographs for intermediate initial soil moisture as well as in dry catchment conditions; in other states the effect was found to be much lower. This is clearly because of the threshold nature of preferential flow as well as the threshold nature of Hortonian production of overland flow. It was shown furthermore that the spatial pattern of a key parameter (macroporosity) that determined threshold behavior is of vast importance for the model response. The estimation of these patterns, which is mostly done based on sparse observations and expert knowledge, is a major source for predictive model uncertainty. Finally, it was shown that the usage of biased, i.e. spatially homogenized precipitation, input during parameter estimation yields a biased model structure, which gives poor results when used with highly distributed input. If spatially highly resolved precipitation was used during model parameter estimation. the predictive uncertainty of the model was clearly reduced. (c) 2005 Elsevier B.V. All rights reserved Y1 - 2005 SN - 0022-1694 ER - TY - BOOK ED - Bronstert, Axel T1 - Abflussbildung : Prozessbeschreibung und Fallbeispiele T3 - Forum für Hydrobiologie und Wasserwirtschaftung Y1 - 2005 SN - 3-937758-91-7 VL - 13 PB - DWA Dt. Vereinigung für Wasserwirtschaft Abwasser und Abfall CY - Hennef ER - TY - JOUR A1 - Lindenmaier, Falk A1 - Zehe, Erwin A1 - Dittfurth, A. A1 - Ihringer, Jürgen T1 - Process identification at a slow-moving landslide in the Vorarlberg Alps N2 - A fine-grained slope that exhibits slow movement rates was investigated to understand how geohydrological processes contribute to a consecutive development of mass movements in the Vorarlberg Alps, Austria. For that purpose intensive hydrometeorological, hydrogeological and geotechnical observations as well as surveying of surface movement rates were conducted during 1998-2001. Subsurface water dynamics at the creeping slope turned out to be dominated by a three-dimensional pressure system. The pressure reaction is triggered by fast infiltration of surface water and subsequent lateral water flow in the south-western part of the hillslope. The related pressure signal was shown to propagate further downhill, causing fast reactions of the piezometric head at 5.5 m depth on a daily time scale. The observed pressure reactions might belong to a temporary hillslope water body that extends further downhill. The related buoyancy forces could be one of the driving forces for the mass movement. A physically based hydrological model was adopted to model simultaneously surface and subsurface water dynamics including evapotranspiration and runoff production. It was possible to reproduce surface runoff and observed pressure reactions in principle. However, as soil hydraulic functions were only estimated on pedotransfer functions, a quantitative comparison between observed and simulated subsurface dynamics is not feasible. Nevertheless, the results suggest that it is possible to reconstruct important spatial structures based on sparse observations in the field which allow reasonable simulations with a physically based hydrological model. Copyright (c) 2005 John Wiley & Sons, Ltd Y1 - 2005 ER - TY - JOUR A1 - Blume, Theresa A1 - Weisbrod, N. A1 - Selker, J. S. T1 - On the critical salt concentrations for particle detachment in homogeneous sand and heterogeneous Hanford sediments N2 - One of the mechanisms for sudden particle release is a decrease in groundwater salt concentration to below the critical salt concentration (CSC), where repulsion forces between fine particles and matrix surfaces exceed binding forces. In this paper, an attempt was made to determine the CSC with both batch and column experiments. Two types of sediments were tested: (a) homogeneous quartz sand and (b) mineralogically heterogeneous sediment, taken from the Hanford formation in southeast Washington. Stepwise decreasing concentrations of NaNO3 solution were applied until fine particles were released from the sediments and the CSC was determined. Two methods were used to minimize the interference of particle release due to physical forces (shear stress) in the batch experiments: (a) postexperimental correction for mechanical effects, and (b) minimization of shear stress on the sediments during the experiment. CSCs from batch experiments were compared to those obtained from column experiments. It was found that both the amount of particles released and the CSC were an order of magnitude higher for the Hanford sediment than for the Sand. Moreover, particle detachment above the CSC was observed for the Hanford sediment. This suggests that the concept of sharp CSCs could be problematic in natural heterogeneous sediments where fine particles may mobilize at salt concentrations significantly above the CSC, thus unexpectedly enhancing colloid-facilitated transport of contaminants. (C) 2004 Elsevier B.V. All rights reserved Y1 - 2005 ER - TY - JOUR A1 - Bloschl, Günter A1 - Zehe, Erwin T1 - Invited commentary : on hydrological predictability Y1 - 2005 ER - TY - BOOK A1 - Oncken, Onno A1 - Götze, Hans-Jürgen A1 - Strecker, Manfred A1 - Franz, Gerhard A1 - Kellner, Antje A1 - Wigger, Peter T1 - Deformation processes in the Andres : international final symposium, April 21 and 22, 2005, Geoforschungszentrum Potsdam, Telegrafenberg T3 - Sonderforschungsbereich Y1 - 2005 VL - 267 PB - Freie Universität CY - Berlin ER - TY - THES A1 - Carstensen, Ines T1 - Ferienhaustourismus - vom Landschaftsfresser zum Innovator für Sustainability Y1 - 2005 CY - Potsdam ER -