Wave overtopping at rubble mound breakwaters with submerged berms: a novel design tool

Wave overtopping represents a critical design issue for rubble-mound breakwaters, particularly in the current context of climate change. This study investigates the influence of submerged berms on overtopping phenomena at rubble mound breakwaters through an integrated experimental–numerical approach, considering its inclusion both in the design of new structures and in the upgrading of existing ones. Small-scale physical model tests have been conducted to qualitative validate the numerical model computations, providing insight into the response of overtopping discharges under varying sea states and berm configurations. A comprehensive parametric numerical investigation has been subsequently performed using IH2VOF numerical model, focusing on the effects of berm geometry. The model has been calibrated and validated to ensure an accurate representation of both water-surface elevation and overtopping phenomena. Within the tested range, the numerical results indicate that submerged berms systematically reduce overtopping discharges compared to conventional configurations without a berm, with enhanced effectiveness observed for increased berm height and length. Such effects have been synthesized into an empirical reduction parameter, formulated as a function of the dimensionless berm height and length, to be used within existing overtopping prediction methods developed for conventional structures. A comparison between modeled and predicted overtopping discharges demonstrates the reliability of the proposed formulation.