Development and application of a 1D floodplain sedimentation model for the River Rhine in The Netherlands

Over the past decade, concern about the morphological and ecological condition of the rivers Rhine and Meuse has increased. Simultaneously with the projects for rehabilitation, measures were proposed to improve the discharge capacity of the high-water floodway, in order to reduce the risk of river flooding. Although many studies focus on the impact of different landscaping measures on the river hydrodynamics (water level and discharge capacity), little attention is paid to the sustainability of the proposed measures with respect to sedimentation. In this study a one-dimensional (1D) floodplain sedimentation model was developed that estimates average sediment accumulation over floodplain sections and that can be used for estimation of changes in floodplain sedimentation caused by landscaping measures. The model was successfully calibrated and validated using sedimentation measurements carried out at different floodplain sections along the river Rhine in The Netherlands during floods. Application of the model to the main branches of the river Rhine in The Netherlands indicates that the average annual sediment accumulation equals 1.72 kg/m2/yr, or 394 million kg/yr. This is about 13% of the total annual suspended sediment load transported into The Netherlands at Lobith.