The Pannerdense Kop is a bifurcation point where the Bovenrijn splits into the Waal and the Pannerden Canal. In recent decades, the discharge partitioning changed to more discharge in the Waal at the expense of the Pannerden Canal, which negatively impacts navigation, flood safety and freshwater availability in the downstream river area. This recent change of the river system is linked to changes in bed level that may have started as a result of peak flows in the 1990s. An overview of peak flow impacts on the bed is missing whilst peak flows will occur more frequent and increase in magnitude due to climate change.

This thesis investigates the morphological response of peak flows on the river bed at the Pannerdense Kop, using field measurements and numerical models. Five sources of field data are used, all based on bed level measurements. A 1D Sobek model and a 2D Delft3D model are analysed to determine the peak flow response in these existing morphological models. The model results are compared with the field data.

Results indicate that peak flows seem to cause deposition at the upstream end of the Waal and to a lesser extent at the Pannerden Canal. Additionally, several patches of erosion and deposition over peak flows are related to floodplain outflows, groyne fields, and bends which are not captured in the 1D model because of width smoothing. Changes on this scale are captured in the 2D model although improvement is possible. On a smaller scale, results indicate that river dunes are present during peak flows and disappear in the weeks after the peak. These small-scale changes are not in the models as a result of the grid size exceeding the dune length. One source of field data shows that peak flows may also lead to a large-scale erosion adjustment wave in the Waal, although further research is required to determine whether such large-scale morphological changes occur, to characterize the nature of these changes, and to assess the extent to which they are represented in existing numerical models. These insights improve the understanding on the morphological response to peak flows at the Pannerdense Kop, and the possibilities and limitations of current morphological models.