Numerical modeling and parameters identification of overland and channel flows in watersheds

Abstract

We present a 2D numerical model based on the finite element method FEM to simulate the surface flow of Watershed model. The kinematic wave approximation describing surface water flow under constant rainfall rate with infiltration is considered. Slopes and roughness are varying in space, while rainfall intensity varies in time. Thus, sensitivity to mesh size and time-step studies are carried out to ensure accuracy of results, and comparisons of simulation results with analytical solutions are done to assess the accuracy of the herein used numerical scheme and to validate the model. In this study, an identification procedure is also proposed to estimate the local roughness parameter, by using optimization tools based on CMA - ES (Covariance Matrix Adaptation Evolution Strategy) algorithm. The model was applied to the realistic case of Hirson's watershed (France).