River-dike-floodplain system Interactions and temporal dynamics for large-scale flood risk assessment

Abstract

In a complex network river, hydrodynamic interactions – changes of hydrodynamic characteristics downstream due to upstream effects – play an important role when determining flood hazard and risk. The correct representation of the hydrodynamic interactions is very important for flood modelling and improves our ability to simulate flood extent and inundation depths. The aggregate effect of these interactions on a large-scale catchment highly affects the overall volume of water inundating the floodplain. In this study, the Derived Flood Risk Assessment “DFRA” approach is applied in the Rhine catchment based on the Regional Flood Model (RFM), where two versions of the Regional Inundation Model (RIM) are compared. The two versions are characterized by different routing approaches (piece-wise and continuous routing) and by different cross-section estimation methods. Results show a significant difference between the inundation patterns resulting from the two routing approaches. The continuous routing approach results in less overtopping downstream, while almost no difference is simulated in the upstream part of the network.