NUMERICAL SIMULATION OF WAVE OVERTOPPING BREAKWATERS

Abstract

The flow discharge induced by wave overtopping the nearshore coastal defence structures, such as shore-parallel breakwaters, could significantly alter the current circulation patterns around the structures. Consequently, it will affect the sediment transport and formation of tombolos and silents. As part of a UK EPSRC funded research project - LEACOAST2, a depth-averaged morphological model has been further developed to include a wave overtopping module. The new development allows the effect of wave overtopping on the hydrodynamics and sediment transport, as well as the resulting morphological changes around the nearshore structures to be studied. The hydrodynamic aspects of the model were validated against the large scale laboratory experiment data from the DELOS project. The model was then applied to the LEACOAST2 site at Sea Palling, Norfolk, UK, where 9 shore-parallel segmented breakwaters were built. The breakwater scheme in this study consists of 4 surface-piercing breakwaters and 5 low-crested breakwaters. The model was used to simulate a storm event in Nov 2006, driven by the measurements taken from the site during the field campaigns of the project. The results show that the wave overtopping has a significant impact on the nearshore hydrodynamics and morphodyanics during the 200-hour storm, particularly under the macro-tide conditions at the Sea Palling site.