Flood forecast uncertainty and alert decision. application to the alpine Rhone river catchment / Incertitude des prévisions de crue et décision d’alerte. Application au bassin du Rhône Alpin

The main goal of the 3rd Rhône Correction project in Switzerland is to improve the flood protection in the Upper Rhone River basin. In this framework, the MINERVE project contributes to the flow control during flood events by preventive turbine and bottom outlet operations from the numerous storage power plants existing in the watershed. For this purpose, a semi-distributed hydrological model was developed for the Upper Rhone River basin. It is currently operational for a real-time flood forecast in the Rhone Valley. It simulates the snow and glacier melt, soil infiltration and run-off processes, flood routing in rivers and reservoirs as well as hydropower scheme operations. For the computation of flood prediction, the numerical meteorological forecast models COSMO-2, COSMO-7 and the probabilistic COSMO-LEPS, delivered by MeteoSwiss, have been assimilated. The forecasts were used as input for the hydrological simulation of three historical flood periods and the results are analyzed and discussed. Furthermore, a warning report providing flood warnings has been also developed. It gives the evolution of the hydrological situation at control points in the catchment area. Finally, it provides three levels warnings during a flood situation depending on respective critical discharge thresholds.