River Flood Modeling: a comparison of different numerical schemes

The Emilia-Romagna Region (Northern Italy) in the past years was hit by multiple river floods that caused huge social and economic losses. The process of adaptation and the design of countermeasures against these events require large investments. Thus, decision makers must rely on reliable and accurate flood hazard and flood risk assessments, obtained by means of the implementation of most appropriate methodological framework and numerical schemes. The hydraulic models are largely used to provide fundamental variables, such as water depth, velocity vector and water surface elevation. Perhaps, 1D, 2D and 3D numerical schemes can provide such output with different levels of details, making each scheme appropriate to a specific scenario. For this study three HEC-RAS geometries were created: full 1D and full 2D schematic, and one that links the 1D and 2D schematic; in addition, a 2D model was created adopting the SaferPlaces approach. In this study a twenty-year return time flood wave of the River Po was simulated inside the river stretch that goes from Cremona to Isola Pescaroli. The study focuses on both the riverbed and its overbanks comparing the models built with HEC-RAS and SaferPlaces. The study proceeds with a comprehensive analysis of the costs to set-up and run the different models, as well as with a comparison of the results in order to identify the best numerical solution to model the complex river-floodplain interaction.