Future evolution of the hydroclimatic conditions favouring floods in the south‐east of Belgium by 2100 using a regional climate model

Abstract

AbstractIn Belgium, most flood events occur in winter as a result of intense precipitation events but also through the abrupt melting of the snowpack that covers the Ardennes summits. These conditions favourable to floods exhibit a decreasing trend over 1959–2010 resulting from the reduction in snow accumulation, although extreme precipitation events show a positive, albeit non‐significant signal. In this study, the evolution of these trends in warmer climates is investigated by using future projections performed with the regional climate model MAR (‘Modèle Atmosphérique Régional’) forced by two global models NorESM1‐M and MIROC5 under the RCP8.5 scenario. These models were selected from the CMIP5 archive after evaluation of their ability to represent the current (1976–2005) mean climate over Europe. By the end of the century, the results show an acceleration of the snow depletion resulting in fewer snowmelt‐associated flood risk days depending on the warming rate from the global models forcing MAR. Regarding the impact of the evolution of extreme precipitation events on hydroclimatic conditions favouring floods, no significant change was found although these trends are subject to uncertainties due to model physics and natural variability.