Quels futurs possibles pour les débits des affluents français du Rhin (Moselle, Sarre, Ill) ?

The MOSARH21 project evaluated the future impacts of climate change on streamflows from the French tributaries of the River Rhine based on recent climate projections (CMIP5 experiment). The adopted methodology relies on two hydrological models (GRSD and LARSIM), used jointly with an ensemble of climate projections disaggregated at the local scale. The impacts were quantified with several indicators describing rivers regimes, floods and low flows. The evolutions of mean interannual streamflow indicate a slight increase, which could even become important for the radiative scenario RCP 8.5 (the most pessimistic one in terms of climate warming). Flood could intensify in the near future (2021-2050). In the far future (2071-2100), the evolution of floods indicators is more uncertain, as the hydrological projections diverge. Low flows could be decreasing in the near future. Their evolution in the far future is more uncertain, going from drastic decrease to sensible rise depending on the chosen scenario. The results were compared to those from previous impact studies performed on the basin. Given the methodological differences and the obtained results, we can conclude that the MOSARH21 project is consistent with the conclusions of the previous studies.