Author(s): P. Narinesingh; Gerrit J. Klaassen; Dik Ludikhuize
Abstract: Large scale changes in floodplain geometry, as contemplated for the Rhine River as part of combined renaturalisation and flood control projects in The Netherlands, will change the rate of floodplain sedimentation. To investigate the seriousness of the anticipated increase, a modelling approach was developed to simulate floodplain sedimentation along extended river reaches with a series of floodplains alternatingly located on both sides of the main channel. The floodplains are schematised as sedimentation basins, which function as sinks for the suspended sediment, which is conveyed to the floodplains during floods via convective transport from the main channel. To assess the deposition of fine sediments in a floodplain, the method of Chen (1975) is used. Via the repetitive use of the continuity equation for fine sediments, a longitudinal reduction in sediment concentration is found. The modelling approach was verified using suspended load data from the IJssel River, one of the distributaries of the Rhine River in The Netherlands, during flood. Using the developed approach the local and the downstream effect of e.g. lowering the floodplain levels with several meters could be determined.