Field Observation and Numerical Modelling on the Hydrodynamics Behind a Submerged Breakwater

Abstract

In 2014, a submerged breakwater installed near the erosion hot spot and the beach is being formed to salient beach behind the structure at Anmok beach, which is located on the east coast of Korea. The field monitoring has been carried out for past three years in order to investigate the change of beach morphology and shoreline before and after the breakwater construction. Wave gages were installed in the offshore location, in front of the breakwater and in the behind of the breakwater to investigate the wave height variation. A three-dimensional numerical model based on the Navier-Stokes equation with a Large Eddy Simulation (LES) turbulence closure scheme (LES-WASS-3D) was employed to predict the hydrodynamics near the submerged breakwater. The model used the beach topography and the bottom bathymetry before the breakwater construction to predict the wave transformation, refraction and diffraction due to the installation of the breakwater. The model simulated the wave and nearshore current fields especially behind the submerged breakwater and successfully predicted the wave heights near the submerged breakwater in high correlation (r(2) = 0.98) with the filed observation results. The numerical results also showed that the predicted wave and current fields could induce the sediment deposition behind the structure.