Shoreline changes due to groin construction in Namae and Sodol Beaches, South Korea

Abstract

The present study beach has a long stretch of 5.271km bounded by Namae Harbor in north and Sodol Harbor in south which are located in the eastern coast of Korea. In 2007, a groin was constructed at the southern part of Namae Harbor. In order to analyze the pattern of shoreline change due to the groin construction, a beach survey has been accomplished since 2008 right after the groin construction. The temporal and spatial changes in beach topography are also investigated based on the echo sounding data. The survey data along the coastline showed that a continuous accretion occurred around the groin in the south of Namae Harbor due to the north-directed currents mainly due to diffracted waves formed after the groin construction. Thus the southern beach of study area has been eroded steadily. Also, beach widths and plane area of the beach in the south of the groin were decreased in summer and was increased in winter season. In winter, the ground-based surveying was even impossible due to the severe sand loss in the southern part of study area. Moreover, the survey results revealed that the beach volume was increased and foreshore slope became steeper in 2011 than 2010 survey. Therefore, the continuous beach monitoring along the shoreline is necessary, especially in the seriously eroding beach such as Sodol Beach. More fundamental measures for reliable prediction of potential beach change prior to complementary construction of coastal structures are also needed to maintain the value of the beach.