Rapid prediction of flood inundation

Abstract

Historically, buildings have been built on floodplains ignoring the danger from the risk of flooding. The need for large scale (national) and probabilistic flood risk assessment has resulted in the development of a number of rapid flood modelling methodologies. These methods are approximate and generally ignore inertia in the estimation of flood extent. Therefore, the advantage of short run times of those rapid flood modelling methodologies is restricted by the limitation in the accuracy of the predicted results. On the other hand, full hydrodynamic models (such as TUFLOW) provide detailed predictions of the flood flow parameters, although they are time consuming to run. Consequently, the need for a new Rapid Flood Model which provides more detailed predictions is obvious. In this thesis, several inflow volume scenarios were tested and results from both the RFIM and TUFLOW were compared in an attempt to provide a critical appraisal for the RFIM technique. This comparison showed that in a lot of relatively simple cases both models predicted similar flood parameters. Exceptions occur being where inertia has a significant influence on flood propagation and it is clear that care must be taken when applying the RFIM to such circumstances. The new Rapid Flood Model improved on this limitation for water level predictions. For most of the inflow volume cases investigated the new model displayed similar water level values to TUFLOW and the difference between these values reduced as the inflow volume increased.