Impact of global warming on streamflow drought in Europe

Recent developments in climate modeling suggest that global warming is likely to favor conditions for the development of droughts in many regions of Europe. Studies evaluating possible changes in drought hazard typically have employed indices that are derived solely from climate variables such as temperature and precipitation, whereas many of the impacts of droughts are more related to hydrological variables such as river flow. This study examines the impact of global warming on streamflow drought in Europe by comparing low-flow predictions of a hydrological model driven by high-resolution regional climate simulations for the end of the previous century and for the end of this century based on the Special Report on Emissions Scenarios A2 greenhouse gas emission scenario. For both time slices, low-flow characteristics were derived from the simulated streamflow series using extreme value analysis. More specifically, we employed the methods of block maxima and partial duration series to obtain minimum flows and flow deficits and fitted extreme value distributions by the maximum likelihood method. In order not to mix drought events with different physical causes the analysis was performed separately for the frost and nonfrost season. Results show that in the frost-free season streamflow droughts will become more severe and persistent in most parts of Europe by the end of this century, except in the most northern and northeastern regions. In the frost season, streamflow drought conditions will be of less importance under future climate conditions.