Hydrodynamic models for coastal flooding and surface runoff assessments along the coast of Ofanto River (Apulia, Italy)

The application of hydrodynamic models serves as a fundamental benchmark in coastal engineering applications. Specifically, the evaluation of coastal flooding and surface runoff constitutes essential research topics that can inform intervention strategies. Coastal regions, particularly those near river mouths, are severely impacted by flooding during extreme wave events. In addition, these areas have undergone severe erosional processes, resulting in significant land-use loss. This study employed hydrodynamic models to evaluate coastal flooding using Delft3D and XBeach, as well as to assess surface runoff employing HecRas, focusing on the coastal regions surrounding the mouth of the Ofanto River in Apulia, Italy. This coastal area features an alluvial plain with salt marshes extending up to 2 kilometers inland. A Digital Elevation Model (DEM) was generated from LiDAR data provided by the former Italian Ministry of the Environment, with bathymetric data sourced from the Italian National Hydrographic Institute. Meteorological and marine parameters were extracted from observational data collected by tide gauges operated by the Istituto Superiore per la Ricerca e Protezione Ambientale (ISPRA), as well as from reanalysis products from ERA5 and Copernicus. The hydrodynamic models were forced using the meteorological and marine parameters from a storm that occurred in November 2019. Results from the models indicated extensive coastal flooding in the backdune areas, illustrating dune breaching and surface runoff, with water levels exceeding 2 meters in elevation. The application of hydrodynamic models enhances the prediction of flooding surfaces and elucidates the morphodynamic processes, particularly in low-lying coastal regions impacted by strong storm events.