Global change and hydrological cycle: A regionalization study over France

As most of Europe, France might undergo severe climate changes during the 21st century. <br />In this thesis we study the impacts of these changes on the hydrological cycle, at the scale <br />of the French river basins. A statistical downscaling method, based on the concept on weather types is built and applied to regionalize an ensemble of climate scenarios in order to force an hydro-meteorological model. Severe impacts occur as soon as the middle of the 21st century, characterized by a strong decrease of mean river flows and a great increase in the occurrence of low-flow. <br />Other downscaling methods are used in order to test the sensivity of the results to the choice of the method: this sensivity is limited. Actually, the main source of uncertainty lies in the choice of the climate model. To finish, we try to better understand the reasons for the spread of the climate change scenarios over Europe.