Regional-scale 2D hydraulic modelling for the assessment of the residual flood hazard due to levee breaches

In the present work, the potential applicability of fully two-dimensional (2D) hydrodynamic models to regional-scale flood simulations is verified by assessing the residual flood hazard in a vast lowland region (> 3500 km2) threatened by possible inundations due to levee collapses in case of extreme flood events on the Po River (Italy). Thanks to the adoption of an efficient GPU-accelerated 2D shallow-water code (PARFLOOD, developed by the authors), the simulations of several hypothetical inundation scenarios could be run using a grid with an ade-quately fine resolution, still maintaining high ratios of physical to computational time, in the order of 50-100. The feasibility of regional-scale fully 2D flood modelling is thus confirmed.