Analysis of Wave and Current in Haeundae Coastal Waters

Lim, Hak-Soo

doi:2016.3.2.59

J Coast Disaster Prev > Volume 3(2); 2016 > Article

Journal of Coastal Disaster Prevention 2016;3(2):59-66.
DOI: https://doi.org/10.20481/kscdp.2016.3.59 Published online April 30, 2016.

Analysis of Wave and Current in Haeundae Coastal Waters

Hak-Soo Lim

해운대 해역의 파랑 및 흐름 분석

임학수

Abstract

To prevent the beach erosion and to support the beach restoration project in Haeundae, the Korean government initiated R&D project, the development of coastal erosion control technology since 2013. As a part of this project, waves and currents have been observed by AWACs in the nearshore and offshore of the Haeundae beach continuously for more than two years, to understand the processes of coastal waters and sediment transport in Haeundae. The variations of residual current and wave were estimated analysing two-year-long AWAC data measured at the mean water depth of 22 m and other short term data obtained near the surf zone of the Haeundae beach, respectively, during summer and winter. IOS T_TIDE and the moving average method for the current data over a fortnightly period (MSf) were applied for estimating the speed and direction of wave-induced current and residual current. A numerical simulation using a wave and current coupled model (ROMS-SWAN) considering wave-tide interaction in Haeundae coastal waters was also conducted for determining the wave-induced current during summer and winter seasonal swell waves (Hs : 2.5 m, Tp: 12 s), for better understanding of the coastal process near the beach. By comparing the measured data and simulated result, we found that cross-shore current during summer season is mainly caused by the eddy produced by the wave-induced current near the beach, which in turn, is generated by the strong waves coming from the S and SSW directions. During other seasons, longshore wave-induced current is produced by the swell waves coming from the E and ESE directions. The wave-induced current also generates longshore current heading west toward Dong-Back Island, west end of the beach, during all the seasons and eddy current toward Mipo-Port, east end of the beach, in summer which is well matched with the estimated residual current. In this study, we especially show the circulation patterns derived from nearshore wave-induced current and offshore residual current causing beach erosion and sediment transport in Haeundae coastal waters.

Key Words: Haeundae circulation; residual current; wave-induced current; beach erosion; sediment transport