Recent development and application of a rapid flood spreading method

Flood risk analysis increasingly involves the integration of a full range of loading conditions as well as multiple defence system states, overlaid by uncertainty analysis. This type of analysis involves the simulation of many thousands of flood events. To keep model runtimes to practical levels an efficient yet robust flood inundation model is required. To accommodate this need a rapid flood spreading model (RFSM) has been developed that utilises the availability of good quality topography data and advanced GIS techniques. This paper describes recent improvements to the RFSM that have focused on incorporating additional physical processes within the spreading algorithm (multiple spilling and friction). This improved model is applied to a number of different sites with comparisons made to a more complex hydrodynamic model. The findings of this comparison demonstrate a good degree of similarity between the RFSM and more complex models, with a significantly reduced runtime overhead.