Detailed 2D flow simulations as an onset for evaluating socio-economic impacts of floods

A 2D hydraulic numerical model is presented. It is based on the fully dynamic shallow-water equations, solved by means of a finite volume scheme on multiblock structured grids. The model handles highly accurate DSM derived from airborne laser altimetry for the floodplains and sonar detection for the bathymetry of the main channel. The flow simulations are performed with a typical grid spacing of 2m, comparable
to the resolution of the DSM and fine enough to represent reliably the flows at the scale of each building. Consequently, the model succeeds in predicting accurately the pattern of flood depth even in densely urbanized floodplains, as confirmed by several validation examples, which also demonstrate the ability of the model to reproduce depth measurements for a wide range of flood discharges without the need for recalibration
of the roughness coefficient. Finally, the hydraulic model is exploited as a component of a complete flood risk modelling chain, accounting for socio-economic and ecological impacts of floods and dedicated to the assessment of flood protection measures in the context of climate change.