Climate change and floods – findings and adaptation Water Science & Technology strategies for flood protection in Baden-Wu¨ rttemberg W. Hennegriff Federal Institute for Environment, Measurements and Nature Protection Baden-Wu¨rttemberg, Landesanstalt fu¨r Umwelt, Messungen und Naturschutz Baden-Wu¨rttemberg (LUBW), Griesbachstraße 1, D–76185 Karlsruhe (E-mail:
[email protected]) Abstract The climatic conditions in Southern Germany have changed noticeably in the 20th century, especially during the last three decades. Both in specific regions and interannually, the trends found Vol 56 No 4 pp 35–44 exceed the natural margins of deviation previously known from long measurement series for some measured quantities. The mean and also the extreme floods are expected to increase significantly, although the results of the model chain global model–regional climate models–water balance models are still uncertain. As a precaution an adaptation strategy has been developed for the field of flood protection which takes into consideration the possible development for the next decades and also takes into account the uncertainties. Keywords Air temperature; climate development modelling; flood protection; flood runoff; precipitation; Q snow cover IWA Publishing 2007 Initial position and cause The numerous extreme floods of the recent past involving extensive damage have pro- voked heated discussions, both in public and among experts, as to whether these flood events must be considered as part of natural climate variation or as a result of climate change already in progress with long-term future effects. According to current prognoses of climate researchers the large-scale climate in the European region will undergo changes, over and above the natural variations, due to anthropogenic influences and in particular due to the increasing CO2-concentration and other increasing greenhouse gas concentrations in the air.