Developing a Prediction System for the Invasion of Swell-like Waves on the Southern Coast of Korea

Abstract

Recently, several drowning accidents caused by rip currents were reported along Haeundae Beach, located at the southeastern corner of the Korean Peninsula. Several dozen people were swept away by rip currents, and subsequently rescued between August 7 and 10, 2012. The main cause of rip currents is swell waves that approach the shore. The rip current becomes more dangerous when a relatively long-period swell-like wave invades and is intensified, during the passage of typhoons far off shore. However, existing wind wave models require significant computational cost and time to obtain solutions to a set of partial differential equations, and have low accuracy for predicting the invasion of swell-like waves on coasts because they simultaneously calculate wind wave generation and wave propagation. In this study, we used a fractional step method to solve the wind wave generation and swell wave propagation components, in which the former is simulated using a typical spectrum approach and the latter is simulated using a Lagrangian approach. The results from the theoretical model were compared with field data collected during the dangerous rip current events in August 2012.