Hydrological simulation in the Mediterranean region with SAFRAN-ISBA-MODCOU. Improvement of the physics of the model and evaluation of the risk within the framework of climate change

The SAFRAN-ISBA-MODCOU model is assessed and its physics are improved; The SAFRAN meteorological analysis is first validated in details. The surface model ISBA is then modified to better describe the hydraulic conductivity in the soil. A strategy of calibration is defined and applied at the scale of France. The improved model is then used to assess the impacts of climate change in the Mediterranean region. A regional climate model is downscaled by two different methods. The study shows that the uncertainties related to the impact model is smaller, but must be taken into account for the extremes. In this region, the extremes of river flows, and sometimes the means, will increase during the first half of the twenty first century. At the end of century, the scenario indicates a decline of the average of riverflows and the extremes will remain stable, leading to incresed variability