Step-berm structures are commonly used to dissipate wave energy along shorelines. This class of structure is being evaluated for a reservoir embankment for the Comprehensive Everglades Restoration Project in southern Florida. The focus of this study is to determine the engineering response of a step-berm structure for a range of wave, water level, and structure cross-sectional configurations. Wave overtopping rate and wave pressure, measured in a small-scale laboratory physical model study and modelled with a Reynolds-averaged Navier Stokes numerical model (COBRAS), are evaluated. The physical model overtopping results are compared to empirical equations from existing coastal engineering manuals. The results suggest that existing equations are reasonable for this class of structure when used with a step roughness coefficient of 0.6. However, the equations are not capturing all of the berm influence so use of the equations outside of the range of modelled conditions is prone to error. The COBRAS model is found to predict overtopping reasonably well but with significant scatter suggesting further evaluation of the modelled overtopping process is required. COBRAS predicts maximum pressures well, as well as the details of the pressure time series. However, this single-phase hydrodynamic model yields spurious wave slamming spikes resulting from trapped non-fluid pockets between the steep wave face and the structure. These spikes mimic physical wave slamming spikes but are actually numerical anomalies that required filtering. A volume minimization study clarifies the impact of the berm on the overall efficiency of the structure.
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