FullSWOF: A software for overland flow simulation / FullSWOF : un logiciel pour la simulation du ruissellement

Overland flow on agricultural fields may have some undesirable effects such as soil erosion, flood, and pollutant transport. To better understand this phenomenon and limit its consequences, we developed a code using state-of-the-art numerical methods: Full Shallow Water equations for Overland Flow (FullSWOF ), an object-oriented code written in C++. It has been made open-source and can be downloaded from http://www.univ-orleans.fr/mapmo/soft/FullSWOF/. The model is based on the classical system of shallow water (SW) (or Saint–Venant system). Numerical difficulties come from the numerous dry/wet transitions and the highly variable topography encountered inside a field. The code includes run-on and rainfall inputs, infiltration (modified Green-Ampt equation), and friction (Darcy-Weisbach and Manning formulas). First, we present the numerical method for the resolution of the SW equations integrated in FullSWOF_2D (the two-dimensional version). This method is based on hydrostatic reconstruction scheme, coupled with a semi-implicit friction term treatment. FullSWOF_2D has been previously validated using analytical solutions from the Shallow Water Analytic Solutions for Hydraulic and Environmental Studies library (SWASHES). FullSWOF_2D is run on a real topography measured on a runoff plot located in Thies (Senegal). Simulation results are compared with measured data. This experimental benchmark demonstrates the capabilities of FullSWOF to simulate adequately overland flow. FullSWOF could also be used for other environmental issues, such as river floods and dam breaks.