Two-dimensional model for overland flow simulations: a case study

This paper deals with the problem of flood generation and propagation at catchment scale. The main aspect of the work is the use of 2D fully dynamic shallow water equations as tool of analysis for spatial and temporal overland flow evolution starting from an observed or predicted rain input. The paper firstly focuses on the model description. The governing equations and the numerical integration scheme are presented. Then some aspects related to the robustness of the numerical model are discussed providing three techniques able to improve its stability in presence of very shallow water depths over complex topographies. After recalled the main features of the meteorological model used in the paper, attention is focused on the simulation of a real event occurred in a small basin in Italy whose drainage area is around 40 km2. Two simulations are presented in which observed and simulated rainfall have been used, respectively, as input of the overland flow model. The overall result is satisfactory.