Validation of a quasi-2D hydrodynamic river flood model using historical and ERS-SAR derived flood maps

There is an increasing interest in river flood modelling due to the severe flood events in the last decade throughout Europe, Asia and other parts of the world. Modelling of these events can be performed using one-dimensional (1D) or two-dimensional (2D) hydrodynamic models. Although 2D hydrodynamic model are the forefront for river flood modelling and prediction, they are constrained by the high requirements of data and computational time. The aim of this study is to test a quasi-2D modelling approach for the prediction of the flood extent along floodplains. The model used was implemented for the river Dender in Belgium, where floods occurred frequently during the past 10 years. The historical flood events of Dec. 1993 and Jan. 1995 were simulated using the river modelling system Mike 11/Mike GIS. The model results were validated using historical flood maps delineated by water authorities and ERS-SAR satellite radar derived flood maps. Both types of floodmaps delivered complementary validation information. After detection and correction of the coarse model inaccuracies, the model became accurate in the description of the spatial extent of floods and its temporal evolution.