Use of an integrated one dimensional-two dimensional hydraulic modelling approach for flood hazard and risk mapping.

This paper presents the application of a new software tool for modelling fluvial and floodplain hydraulics. The software package, developed by WL I Delft Hydraulics, integrates a one-dimensional (ID) modelling package known as SOBEK-Flow with a two-dimensional (2D) hydrodynamic prediction package known as Delft-FLS (Delft Flooding System). In the combined modelling system, called Delft-1D2D, the 1D channel network and the 2D rectangular grid hydrodynamics are solved simultaneously using the Delft scheme able to tackle steep fronts, wetting and drying processes and subcritical and supercritical flow. The model is applied to simulate the inundation processes on the floodplains of the Liri-Garigliano catchment in central Italy. The implementation of the model and results obtained are described, as well as the generation of flood hazard and risk maps. The results highlight the capability of the software to cope with problems related to flood hazard and risk mapping.