1D/2D porosity model for urban flood modeling: case of a dense street networks

Abstract

An increasing urbanization of floodplains has led to higher vul- nerability of urban areas and building a new generation of robust, accurate and computationally affordable models dedicated to urban floods is highly re- quired for improving prediction systems and mitigation measures. A better understanding of urban floods hydrodynamics may also be required. In view to achieve computationally affordable and reliable simulations a new 1D/2D parsimonious hydraulic model Flood1D2D is introduced for flood modeling in complex branched urban networks. It takes advantage of a cut-cell technique and a new effective model able to take into account some essential sub-grid flow features such as flow vein contractions due to recirculations downstream of a crossroad. It is shown that this local phenomenon can be correctly repro- duced thanks to this 1D/2D coupled SW model parameterized with roughness and porosity. The ability of the model to reproduce realistic flood discharge distributions at the subdistrict scale is also tested on a part of the branched net- work of ICUBE experimental rig. Further studies should tackle the issues of calibration and unsteady modeling.