Climate change and hydrological extremes in Belgian catchments

Abstract. In this study we focus our attention on the climate change impacts on the hydrological balance in Belgium. There are two main rivers in the country, the Scheldt and the Meuse, supplied with water almost exclusively by precipitation. With the climate change projected by climate models for the end of the current century, one would expect that the hydrological regime of the rivers may be affected mainly through the changes in precipitation patterns and the increased potential evapotranspiration (PET) due to increased temperature throughout the year. We examine the hydrology of two important tributaries of the rivers Scheldt and Meuse, the Gete and the Ourthe, respectively. Our analysis is based on simulations with the SCHEME hydrological model and on climate change data from the European PRUDENCE project. Two emission scenarios are considered, the SRES A2 and B2 scenarios, and the perturbation (or delta) method is used in order to assess the climate change signal at monthly time scale and provide appropriate input time series for the hydrological simulations. The ensemble of climate change scenarios used allows us to estimate the combined model and scenario uncertainty in the streamflow calculations, inherent to this kind of analysis. In this context, we also analyze extreme river flows using two probability distribution families, allowing us to quantify the shift of the extremes under climate change conditions.