Analysis of Beach Changes after Construction of Submerged Breakwaters

This study presents seasonal investigations of submerged breakwaters constructed from 2013 to 2014 as part of a government erosion prevention project in the region of Samcheok-si, South Korea. Parameters, including wave-induced currents, wave heights, beach profiles, and shoreline changes, were investigated to monitor and analyze sand transport trends in the study area. The construction of Gungchon Harbor in 2006 led to the transport of sand from southern Wonpyeong Beach to northern Gungchon Beach, which resulted in an average shoreline retreat of greater than 50 m. However, despite the subsequent construction of the submerged breakwaters, beach erosion continued to occur in adjacent areas. Specifically, a tombolo was generated behind the submerged breakwaters, which led to beach erosion. Rip currents were also typically generated near submerged breakwaters, which play a role in the offshore transportation of sand. Wonpyeong Beach experienced erosion following the construction of Gungchon Harbor, whereas Gungchon Beach exhibited accretion. Moreover, evidence of further erosion was observed near the breakwater construction area. Therefore, this study indicates that detailed monitoring during and after the construction of breakwaters is required to predict potential secondary erosion and understand the erosion mechanism for an optimal breakwater design.