Résumé
Mediterranean countries are strongly affected by reduced surface water resources. This study aims to assess the climate change impacts on runoff supply to the Bin El Ouidane dam in Morocco, the largest in the country in terms of hydropower production. A water balance model coupled with a stochastic calibration method to provide confidence intervals on simulated discharge is used to reproduce discharge using observed and bias-corrected ECMWF Reanalysis 5th Generation (ERA5) rainfall (WFDE5). Five regional climate models from the EURO-CORDEX initiative are considered to estimate the climate change impacts on surface runoff for the Representative Concentration Pathway (RCP4.5) and RCP8.5 scenarios. Results indicate a future increase in evapotranspiration (+15 to +36%) associated with a decrease in precipitation (−16 to −34%) in both climate scenarios. The hydrological projections indicated a significant decrease in runoff (−57 to −86%), more severe when the model is driven by WFDE5 compared to observed precipitation. Consequently, the strong decline of surface water resources imply a change in water ressource management for hydropower production and local agriculture to adapt to the future climatic conditions.