Rapid flood risk assessment using GIS technology

Limiting the time and effort needed for setting up and running an inundation model, as well as increasing the flexibility to changes in conditions arising from land use, the location studied and infrastructure, will increase the usefulness of Flood Risk Assessment (FRA) for decision makers. In this respect a traditional 2‐dimensional (2D) hydrodynamic approach for inundation modelling is less desirable. Moreover, such complex models are less suited to uncertainty analyses based on a large number of simulations with multiple sources of uncertainty. This can be better accomplished using a Rapid Flood Risk Assessment (RFRA) approach which requires minimal data and modelling work. The approach is GIS‐based, using only data on land use and elevation as input, and does not require hydrodynamic computations. A small section of the River Elbe in Germany served as case study to examine the applicability of the RFRA approach. For comparison, the inundation process was also modelled with the 2D‐hydrodynamic modelling software SOBEK1D2D of WL | Delft Hydraulics. The results indicated that the rapid approach performs well in terms of estimating the damage caused by inundation depth, but poorly in terms of the dynamic flow velocity effects.