A storm event watershed model for surface runoff based on 2D fully dynamic wave equations

The main purpose of this work concerns the development and testing of an overland flow model based on the two-dimensionalfully dynamic shallow water equations. Three key aspects, fundamental to get accurate, efficient and robust computation ofsurface runoff at basin scale, are discussed by transferring the main findings obtained by the recent research on the topic ofdam-break wave and flood propagation in the context of rainfall–runoff modelling. In particular, attention is focused on thenumerical flux and bottom slope source terms computation, on a numerical treatment of friction slope terms and on an algorithmfor dealing with wetting/drying fronts. The performances of the numerical model have been preliminarily evaluated usingexperimental or ideal tests characterized by very critical conditions for the stability of a numerical model. Then, attention wasfocused on a real event occurred in a sub-basin of Reno river in Italy to analyse the suitability of the model in simulating realflood situations. The numerical results highlight the good performances of the model in all the simulations discussed in the paper.