Expected changes in water resources availability and water quality with respect to climate change in the Elbe River basin (Germany)

Reliable modelling of climate-water interactions at the river basin and regional scale requires development of advanced modelling approaches at scales relevant for assessing the potential effects of climate change on the hydrological cycle. These approaches should represent the atmospheric, surface and subsurface hydrological processes and take into account their characteristic temporal and spatial scales of occurrence. The paper presents a climate change impact assessment performed for the Elbe River basin in Germany (about 100 000 km(2)). The method used for the study combines: (a) a statistical downscaling method driven by GCM-predicted temperature trend for producing climate scenarios,and (b) a simulation technique based on an ecohydrological semi-distributed river basin model, which was thoroughly validated in advance. The overall result of the climate impact study for the basin is that the mean water discharge and the mean groundwater recharge in the Elbe basin will be most likely decreased under the expected climate change and diffuse source pollution will be diminished. Our study confirms that the uncertainty in hydrological and water quality responses to changing climate is generally higher than the uncertainty in climate input. The method is transferable to other basins in the temperate zone.