Variability of Residual Currents and Waves in Haeundae Using Long-term Observed AWAC Data

Abstract

The Haeundae in the southeastern Korean Peninsula is a famous beach which is one of the most popular tourist attractions of Korea in summer. It is about 1.6 km long and 40 m wide facing the southeastern sea of Korea and Korea Strait. During strong winds in winter and severe typhoons in summer, the beach is significantly eroded by waves and nearshore currents in the surf zone. Thin intensive coastal developments during last 30 years have caused substantial beach erosion and bathymetric changes in the nearshore area, despite various beach restoration projects, including beach nourishments. Recently, the government decided to construct two submerged breakwaters near both ends of the beach to enhance the preservation potential of the beach replenishments. We estimated the seasonal variations in residual currents from one-year flow measurements using the Acoustic Wave and Current (AWAC) meter, at two locations of Haeundae at approximately 15 m and 22 m in depths. Short-term flows were measured in the surf zone during summer and winter. The moving average method was applied fortnightly to estimate the residual currents. In addition, waves measured with the AWAC were analyzed to characterize seasonal variations in the beach environment of Haeundae. The observed residual currents were well matched with the simulated counterpart from a wave and current coupled model. These simulated nearshore currents appear well correlated with seasonal variations in beach erosion and accumulation. The wave and current data were also used to validate an operational coastal modeling system for the prediction of hydrodynamics. These observations will be incorporated in simulations of sediment transport in Haeundae coastal waters for developing coastal erosion control system.