The morphological response to peak flows at the Pannerdense Kop

Abstract

The Pannerdense Kop is a key bifurcation in the engineered Dutch Rhine system where the Bovenrijn divides into the Waal and the Pannerden Canal. The discharge partitioning at the Pannerdense Kop is important for the Room for the River 2.0 programme, as it influences navigation, flood safety, and freshwater availability. Observations show that since the 1990s an increasing share of discharge is routed towards the Waal (Fig. 1), accompanied by a stronger erosional trend in the Waal than in the Pannerden Canal (Becker, 2021; Sloff, 2019; Chowdhury et al., 2023). A mechanism which may have caused this change is related to the peak flows in the 1990s, when the incoming sediment flux may have exceeded the transport capacity in the Pannerden Canal (Chowdhury et al., 2023; Blom et al., 2024). This stresses the importance of the morphological behaviour during peak flows. During peak flows, morphological adjustments around the bifurcation occur on multiple spatial scales, from dune dynamics affecting roughness (Julien et al., 2002; Frings & Kleinhans, 2008) to patterns related to floodplains, groynes, and bends (Ahrendt et al., 2022; Parker et al., 2011), yet existing knowledge is fragmented across individual processes and time periods. This research therefore provides a comprehensive multiscale analysis of morphological behaviour at the Pannerdense Kop by combining multiple field datasets with output from 1D and 2D morphodynamic models and systematically comparing their responses.