Yuan, S.; Li, L.; Amini, F., and Tang, H., 2014. Numerical study of turbulence and erosion of an HPTRM-strengthened levee under combined storm surge overflow and wave overtopping.

Combinations of storm surge and extreme waves may cause overtopping of coastal protection of structures, resulting in structural damage and flooding behind these structures. The high turbulence of the overtopping flow is an important factor for soil erosion and may be responsible for the destruction of levees during combined overtopping. The goal of this study was to investigate the turbulence and erosion characteristics of one levee strengthening technique, high-performance turf reinforcement mat, under combined wave overtopping and storm surge overflow. A three-dimensional hydrodynamic and sediment transport model known as ECOMSED has been calibrated and verified with overflow discharge and full-scale overtopping experimental results. The study simulated 41 storm surge overflow and combined overtopping cases with different freeboards and significant wave heights. Overtopping hydrodynamic flow, turbulent shear stress, turbulent kinetic energy, and erosion rate at the toe of a landside slope under combined overtopping conditions were calculated. New equations for estimating turbulent shear stress, turbulent kinetic energy, and erosion rate at the toe of a landside slope were developed. The equivalency of erosion rate under storm surge overflow and combined wave and surge overtopping are provided. The range of the application of these equations is discussed.