Summary Report No. 19


Identification of vulnerable subregions in the Elbe drainage basin under global change impact

V. Krysanova, D.-I. Müller-Wohlfeil, W. Cramer, A. Becker (July 1996)

The main objective of this study was the identification of those subregions of the Elbe river basin that potentially differ in their sensitivity to global change impacts. The drainage basin scale is the most suitable scale for the regionally integrated analysis of the hydrological cycle, biogeochemical fluxes and vegetation dynamics. The Elbe river basin has been chosen for a regional study of global change impact because it is one of the largest river basins in Europe. Also, it has recently undergone significant land use changes and is characterized by relatively low water availability (in some parts) and a high level of pollution. Our study is focused on freshwater availability and erosion. The vulnerable subregions were identified by coupling simplified hydrological (the topography-based WET model) and erosion (a modification of the USLE) models with a GIS. The models were applied to evaluate spatial patterns of the long-term average soil moisture deficits and potential soil loss, and to delineate the critical subregions, based on topography, soil, land use, and climate data. Comparison with long term water availability expressed in ground water table depths showed a good agreement with spatial patterns of the results for the wetness index achieved with WET. The method allows critical subareas within a region or a relatively large drainage basin to be delineated under consideration of patterns of soil moisture and erosion. This approach can be used for sensitivity assessments in large-scale hydrological and water quality studies.