Field observation and numerical analysis of rip currents at Ten-Mile Beach, Hailing Island, China

Abstract

Rip currents are a type of high-speed cross-shore current that occur in coastal areas. They are one of the deadliest natural hazard that occur along coasts. At Ten-Mile Beach on Hailing Island in Yangjiang, China, there have been a number of drowning accidents, most of which have been investigated to be related to rip currents. In order to investigate the rip current phenomenon at this beach, a 24-day beach observation was conducted from August 7 to August 30, 2021. This field investigation included wave observation in the surf zone, bathymetric measurements, unmanned aerial vehicle (UAV) monitoring, and sediment sampling. During the investigation, the beach state changed successively from barred to low tide terrace rip currents and low tide bar/rip, which are beach types with a high probability of rip current occurrence. Wave height was the main factor controlling the beach state and the occurrence of rip currents. The numerical simulation results of the XBeach model were in good agreement with images taken by UAV, confirming that the rip current hazard estimation model can effectively characterize the rip current hazard level for different beach stages. The results of the study provide a useful reference for beach development management and rip current warning at Ten-Mile Beach.