The influence of subsurface architecture on scour hole formation in the Rhine–Meuse delta, the Netherlands

Abstract Scour holes are common features in deltaic rivers which can destabilise embankments through oversteepening of the river bed. Their development has been studied extensively from hydraulic perspective, but another important control is erodibility bed varies considerably due to thickening heterogeneous substrate towards coast. Therefore, we assessed influence delta-scale geological heterogeneity and local subsurface architecture on scour hole formation addition hydrodynamic controls. We (1) created an inventory 165 locations Rhine–Meuse delta, (2) conditions at locations, (3) extracted geometric characteristics (4) determined data. Central lower delta branches have 0.6–0.7 scours per km while upper less than 0.2. Downstream, 58% were related architectural elements, notably sand bodies former Holocene channel belts Early cohesive beds. These steeper slopes higher proportions sediments near Furthermore, belt limited downstream length depth, up maximum approximately two times water depth. From our results, provide a explanatory framework that relates position present-day channels with respect Pleistocene deposits fluvio-deltaic formation. Upstream incised showing variation erodibility. The majority here relate engineering works. In central branches, geologically inherited critical depths bottom adds anthropogenic induced results high abundances. This demonstrates should be considered as key for management purposes.