IN-WOP project WP3 - Seine River study case: Climate change impacts on water resources

This report presents the results of the calibration of the semi-distributed hydrological model of the Seine River Basin up to Vernon, using a set of 156 hydrometric stations. It also presents the simulation of the uninfluenced flow forced by 11 climate projections under RCP 4.5 and 8.5. and the impact of the climate change over the XXIth century on the basin hydrology. This modelling is carried out using the airGRiwrm extension of the airGR package (Dorchies, Delaigue, and Thirel 2022) at daily time step. The calibration is performed using observed influenced flows and known influence of the reservoirs. We use a collection of hydrological indicators characterizing all regime conditions (including droughts and floods) in order to assess this calibration. Removing the reservoirs from the model allows one to simulate the flow without the influence of the reservoirs (Terrier et al. 2020). We use then the climate projections to simulate the evolution of these “uninfluenced” flows under climate change. The simulated “uninfluenced” flows under climate change will be use afterward for assessing the reservoir management risks and for computing the derived “risk-based” rules. In order to assess the climate change impact on water resources, we compute the evolution of hydrological indicators for the near future (2021-2050), the middle (2041-2070), and the end of the century (2071-2100) compared to the reference situation (1976-2005).