Latest Developments in Floodplain Modelling - 1D/2D Integration

In this keynote lecture we describe the current approach to flood modelling in The Netherlands and in particular the recent development of supporting technologies and simulation modelling software. By law, the flood design levels of the principal rivers in The Netherlands are recomputed every five years with the objective of evaluating the effects of floodplain and river bed changes. This requirement has given an impulse to the development of new technologies, such as airborne laser altimetry, used for several years now to monitor efficiently and accurately the floodplain topography. However, recent developments extend the use of laser altimetry technology to the production of flow roughness maps and the monitoring of flood water levels to support model calibration. Another important development resulting from the modelling needs and described in this paper is the integrated fully implicit approach to the combined ID and 2D modelling of rivers, channels, urban drainage systems and floodplains, such as implemented in the SOBEK simulation modelling software of WL Delft Hydraulics.