Urban areas flooding modelling

The present project is aimed at the realization of a non stationary model that integrates optimally a model of propagation in riverbed of the flood wave and one of flooding in urban areas. We chose to simulate the propagation in riverbed of the flood event with a model solving the equations of De Saint-Venant with the explicit scheme at the finite differences by McCormack (Garcia-Navarro & Saviron [2]). The propagation outside the riverbed was simulated with an algorithm proposed by Braschi, Gallati & Natale [l]. This last one is based on a local discretization of the urban territory, which is subdivided in a series of "tanks" and "channels". For each time step, the exchange of water volumes is evaluated as a function of the piezometric level in every tank and these volumes are transferred through the channels using the transport law (in order to estimate the losses of energy) and the equation of continuity. The model has been realized in Visual Basic and needs, as inputs, the data concerning the flood event (hydrogram and boundary conditions), the characteristics of the cross-sections (geometric and hydraulic) and the urban territory (DEM). 1 Introduction The study and containment of flood phenomena requires a broad analytical framework incorporating hydrological and hydraulic aspects of the fluvial system as well as knowledge of the area under study as the effects of flooding on urban zones or scarsely inhabited alluvial plains are quite different. Environmental protection legislation regarding soil conservation and flood prediction and prevention requires the identification of areas of flood pertinence for events with flows corresponding to different return periods. These thus identified areas are an indispensable planning tool in the industrial, agricultural ..