In order to assess the impact of climate change on the hydrology of the Seine and its basin, we constructed three scenarios of climate change from three pairs of simulations using the ARPEGE general circulation model (Météo-France). Their impact was tested using two hydrological models : the model CaB, developed to simulate the water and energy budgets in general circulation models, but ignoring deep aquifers, unlike the hydrogeological model MODCOU. These two models agree, under the three scenarios, on an enhancement of seasonal contrasts, illustrated by larger floods in winter and more severe low flows in summer.