Integrated modelling approach for flood forecasting in small Mediterranean catchment – Application to the Cagne Catchment, France

Abstract

Abstract The French Mediterranean region is vulnerable to flooding caused by extreme rainstorm events. To better predict floods and anticipate consequences, the technical managing services operating on the field need to analyze the hydrological situation, receive accurate forecasts and issue alerts to the exposed population. Within this context, the various needed modelling tools are integrated within a common framework of a Decision Support System (DSS). This approach has been developed and implemented in the Cagne catchment located in the French Riviera. The Cagne catchment covers 96 km2 area and it is densely urbanized with high risks of inundation in the downstream area. The hydrological model MIKE SHE covers 96 km2 with a 20 m resolution. The river network is represented in a 1D MIKE 11 model by 18 branches and 1899 cross sections. The downstream area is covered with a high-resolution hydraulic model built with MIKE 21 FM. The model receives inputs from the hydrological model and can produce detailed inundation maps and forecasts. A major rainfall event observed from October to December 2020 is currently used as validation situation and the built modelling system has demonstrated its efficiency to reproduce the observed processes and to deliver the forecasts on due time.