Wave overtopping and inducing currents at emergent low crested structures

This paper deals with wave overtopping associated to low emergent detached breakwaters. It starts presenting the various mechanisms which define the functional behaviour of detached breakwaters which are frequently overtopped. The emphasis is on the role played by overtopping and how this contributes to the wave pumping in the area around the structure. The paper then reviews the available formulations for predicting overtopping, considering the sensitivity of various equations to climatic drivers and their suitability for low crested coastal structures. The paper then analyses nearshore circulation models and how overtopping discharges can be included. This is illustrated with a sample Q-3D model by analysing the differences obtained with/without overtopping. The emphasis is on the implications for the functional design of the structure and its hydro-morphodynamic impact. The main conclusion is the sensitivity of the functional design of such structures to the underlying hydrodynamics processes and the importance to explicitly include overtopping for numerical simulations of the hydro-morphodynamic behaviour of low crested breakwaters.