Numerical study of combined wave overtopping and storm surge overflow of HPTRM strengthened levee

Overtopping of earthen levees produces fast-flowing, turbulent water velocities on the land-side slope that can damage the protective grass covering and expose the underlying soil to erosion. High performance turf reinforcement mat (HPTRM) is one of the most advanced flexible armoring technologies for severe erosion challenges. In this study, combined wave overtopping and storm surge turbulent overflow of a HPTRM strengthened levee was studied in a three-dimension numerical modeling. The primary objective was to investigate the hydrodynamics of the combined overtopping turbulent flow on the land-side levee slope. Thirty combined overtopping cases with different freeboards and significant wave heights were simulated. After verifying the numerical model with full-scale overtopping experimental data and previous equations, new equations were developed to estimate average overtopping discharge, mean flow thickness, characteristic parameters of wave height and flow thickness, and wave front velocity at the toe of the land-side levee slope for the HPTRM strengthened levee. The range of the application of these equations is discussed.