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Abstract:
The debate over whether the recent floods in Germany were partly generated or aggravated by anthropogenically caused changes of the climatic system, of vegetation and land-use or of the river systems was the occasion for the German Science Foundation to initiate an expert meeting to discuss the existing knowledge about "Flooding and its Links to Global Changes", the results of which form a basis of this paper.
Climatic change is mainly affecting the meteorological conditions and - to a lesser extent - the situation of the catchment surface, such as vegetation and soil conditions. The state of the river system and the damage potential in the catchment are not affected by climatic changes. Discussing the rainfall-runoff processes causing floods requires the distinction of different space and time scales: high intensity, locally restricted rainfall events (thunderstorms), and long lasting rainfall, covering large areas.
Quantitative general statements about the changes of flooding risk due to climatic change are hardly possible. One has to deal with a very complex, highly nonlinear and space-time variable system which is exposed to the natural driving forces topography, soil, vegetation, climate, ground water level and river conditions. The current knowledge of climatic change effects on river flooding in Germany is summarized. The report ends with an overview of open questions and research needs.
