Numerical modelling of large-scale coastal wave impacts in shallow foreshore conditions

Low-lying countries typically have mildly-sloping beaches as part of their coastal defence system. For countries in north-western Europe high-rise buildings are a common sight close to the coastline. They are usually fronted by a low-crested sea dike with a relatively short promenade, where the long (nourished) beach in front of it acts as a very/extremely shallow foreshore as defined by Hofland et al. (2017). Along the cross-section of this hybrid beachdike coastal defence system, storm waves are forced to undergo many transformation processes before they finally hit the buildings on top of the dike. These hydrodynamic processes include: shoaling, sea and swell wave energy transfer to sub- and superharmonics via nonlinear wave-wave interactions, wave dissipation by breaking and bottom friction, reflection against the dike, wave run-up and overtopping on the dike, bore impact on a wall or building, and finally reflection back towards the sea interacting with incoming bores on the promenade