Wave Overtopping Generated Flow Through Offshore Breakwater Gaps

This note describes a simplified method for estimating the flow rate and flow velocity through the gaps of permeable offshore segmented breakwaters caused by wave overtopping. The method incorporates previous two-dimensional laboratory tests and resulting empirical equations for estimating ponding (setup) behind the breakwater. Factors that can be investigated using this method are the influence of breakwater freeboard, wave height and period, breakwater length and spacing, number of breakwaters, distance offshore, water depth at the breakwater, and shore attachment on the flow rate. Other wave effects on hydraulics, such as diffraction, refraction, reflection, and wave-current interactions, have not been considered. The method can be extended to other similar situations via laboratory testing and/or analytical results on flow through and over breakwaters.