Climate change impacts on hydrology and water resources

Aim of our study is to quantify the impacts of climate change on hydrology in the large river basins in Germany (Rhine, Elbe, Danube, Weser and Ems) and thereby giving the range of impact uncertainty created by the most recent regional climate projections. The study shows mainly results for the A1B SRES (Special Report on Emission Scenario) scenario by comparing the reference period 1981-2010 and the scenario periods 2031-2060 and 2061-2090 and using climate projections of a combination of 4 Global Climate Models (GCMs) and 12 Regional Climate Models (RCMs) as climate driver. The outcome is compared against impacts driven by a more recent RCP (Representative Emission Pathways) scenario by using data of a statistical RCM. The results indicate that more robust conclusions can be drawn for some river basins, especially the Rhine and Danube basins, while diversity of results leads to higher uncertainty in the other river basins. The results also show that hydrology is very sensitive to changes in climate and effects of a general increase in precipitation can even be over-compensated by an increase in evapotranspiration. The decrease of runoff in late summer shown in most results can be an indicator for more pronounced droughts under scenario conditions.