The influence of subsurface heterogeneity on scour hole development in the Rhine-Meuse delta, the Netherlands

River dikes are the primary form of flood protection of the Rhine-Meuse delta in the Netherlands. The newly adopted risk approach for the management of flood defenses, requires quantification of multiple failure probabilities in dike stability assessments. The stability of dikes may be compromised where deep scour holes develop in the rivers nearby. Scour holes are a form of bed erosion that impose increased probability of channel bank instability (e.g. flow slides along steepened sides of the bed) and hence of dike failure. This is especially the case for scour holes in the lower reaches of the Rhine-Meuse delta, where most dikes are located close to the main channel.