Modelling suspended sediment supply to the River Rhine drainage network; a methodological study

In the framework of a climate change research project, an approach and preliminary results are presented of modelling the suspended sediment supply to the drainage network of the River Rhine. Concepts of the GAMES model are used as a basis. In the model, the amount of mobilized sediment that actually reaches the stream network depends on the proximity of the sediment source to the stream, the occurrence of overland flow and on the character of the terrain along the route towards the channel (including surface roughness and slope angle). Attention is paid to problems that are specific to the large size of the studied basin and the spatial resolution of the available data set. Preliminary results show that estimates of sediment supply from hillslope to streams are reasonable. Calculated sediment supply was compared with measured sediment yields at several sampling stations in the Rhine basin. It appeared that suspended sediment supplied in lower parts of the basin is transported more effectively through the alluvial system. A large part of the sediment produced in the Alps and in the Swiss middle mountains is stored in the alluvial system further downstream where stream power decreases.