Computing flooding of crossroads with obstacles using a 2D numerical model

Urban flood flow characteristics are usually computed using two-dimensional numerical models. How such modelling can be implemented in dense urban areas with obstacles is investigated in this paper. A strategy for representing the effect of urban obstacles in various flow conditions is proposed. The comparison between the available laboratory measurements and the model results show that if the water depth is high enough and the flow remains subcritical, two-dimensional modelling with constant eddy viscosity represents the effect of the obstacles on the flow distribution accurately, even with a coarse mesh. In contrast, if the water depth is low and/or the flow becomes supercritical, the description of the flow is not sufficient and it generates errors in the flow distribution at the crossroads.