Assessment of land use and climate change impacts on the mesoscale

Studies of Global Change impacts on the regional water cycle induced by a changing climate or by land use changes belong to the urgent issues of today's hydrologic research. Since the most important sources and drivers of Global Change are located at the regional scale, a stronger emphasis is needed at this scale, where political and technical measures can be taken in order to avoid critical developments for the environment and society. With respect to climate changes, studies indicate considerable regional vulnerabilities against changes of both temperature and precipitation. Land use or land cover changes, on the other hand, represent another anthropogenic 'system disturbance' which directly or indirectly influences many hydrologic processes. The present study outlines a methodology to derive and analyse scenarios, which allow to assess the influences of both climate acid land use changes in a region. The results of a high resolution modelling approach demonstrate the chances and problems in such types of studies. The climate change impact studies performed in the German state of Brandenburg and in the Stepenitz river basin show that some of the water balance components may undergo a considerable change. Due to their high evapotranspiration potential, wetlands and open water bodies have turned out to be the most sensitive areas. The results of the land use change impact studies performed in two mesoscale river basins demonstrate that moderate land use changes result in only small changes of various water balance components. For the effects of land use changes climatic characteristics in a region seem to play a crucial role. (C) 2001 Elsevier Science Ltd. All rights reserved.