B-flood 1.0: an open-source Saint-Venant model for flash floodsimulation using adaptive refinement

Abstract. The French Riviera is very often threatened by flash floods. These hydro-meteorological events, which are fast and violent, have catastrophic consequences on life and properties. The development of forecasting tools may help to limit the impacts of these extreme events. Our purpose here is to demonstrate the possibility of using b-flood (a subset of the Basilisk library http://basilisk.fr/ ) which is a 2D tool based on the shallow water equations and adaptive mesh refinement. The code is first validated on analytical test cases describing different flow regimes. It is then applied on the Toce river valley physical model produced by ENEL-HYDRO in the framework of the CADAM project and on a flash flood case over the urbanized Toce produced during the IMPACT project. Finally, b-flood is applied on the flash flood of October 2015 on Cannes city in south-east France, which demonstrates the feasibility of using a software based on the shallow water equations and mesh refinement for flash flood simulation on small watersheds (less than 100 km2) and on predictive computational time scale.