In the paper, the coast area at Sea Palling, Norfolk, UK has been studied, where 9 shore-parallel segmented breakwaters were constructed, including 4 surface-piercing and 5 low-crested breakwaters. The time-varying natural waves and tides combined with man-made a group of shore-parallel breakwaters makes the coastal morphology considerably complicated. In order to identify the main drivers on the morphological changes in nearshore region, a two dimensional depth-integrated and wave period-averaged coastal morphological model: COAST2D, is used to model 10 designed cases to analyze the beach and morphological response under 2 meso-tides and 4 wave conditions. The computed results shows wave height dominates the quantities of sediment transport volume, and wave directions as well as tides type such as neap and spring tides can change the morphological erosion and deposition patterns.
Various coastal structures in nearshore area were widely built to protect the beach and reduce the coastal erosion which mainly caused by waves, tides and storm surge. Under the background of a predicted increase in storm frequency and the height of storm surge levels due to global climate change, they might play more vital functions to defend the storms and maintain the shoreline. To improve the existing design guidelines for such structures, many laboratorial physical models and numerical models are applied and lots of achievements are obtained. Generally, the physical models are mostly applicable to single breakwater. The numerical models are flexible and widely used to simulate the coastal morphological changes with breakwaters in many kinds of situations, see de Vriend et al. (1993), O"Connor et al. (1995), Nicholson et al. (1997), Zyserman and Johnson (2002), Cáceres et al. (2005), and Iskande (2007). They become the important tools to investigate the morphological processes at the coastal area with some kinds of breakwaters.