Wave overtopping and transmission: an interpretation of spectral changes at low-crested rubble mound structures

This paper analyses wave transformation in presence of low crested permeable structures aiming to develop a simple, physically based model for the interpretation of the shape of transmitted wave spectra. The transmitted wave is reconstructed as the sum of the overtopped and filtered components of the incident wave. Incident waves transform seawards the structure into overtopping events and then regenerate, leewards the structure, due to perturbations caused by impulsive overtopping volumes. The overtopping and filtration discharges are added and converted into displacements of an ideal wave maker placed leewards the structure. This scheme is verified by means of 2D and 3D experimental data, obtaining a fair agreement between simulated and measured spectra, in particular when overtopping is prevailing on filtration.