Résumé
The Mediterranean region is considered as a hot spot of climate change, where precipitation islikely to decrease with the rise of temperature. These changes could have a strong effect in north Africa andnotably in Morocco where the agricultural sector is of high importance and very dependent on surface waterresources. Therefore, there is a need to quantify the possible climate change impacts on water resources ofthis region. The most common approach to conduct hydrological impact studies of climate change is to runhydrological models with climate scenarios, usually provided by climate model outputs downscaled to thecatchment of interest. In the present study an ensemble of six regional climate model (RCM) simulationsfrom the European project ENSEMBLES at a 25 km resolution is considered to evaluate the climate changeimpacts on the inflows of the sixth largest dam located in northern Morocco. A quantile perturbation methodis used to generate future temperature and precipitation series under the emission scenario A1B. The GR4Jhydrological model is first calibrated on different climatic conditions to assess the temporal transferability ofits parameters and then run with the perturbed temperature and precipitation series. The ensemble approachallows the projection uncertainties to be evaluated from the spread in the individual RCM simulations. AllRCM simulations project a decrease in surface water resources during the extended winter season(November to May), from –9% to –54% depending on the model.