Risk assessment of rip current in China: based on data from 33 beaches

Rip currents are narrow, powerful seaward currents that frequently occur on sandy shores, posing a significant hazard by quickly pulling swimmers into deeper waters, leading to numerous drowning incidents. As such, they are among the most dangerous natural threats in coastal zones. The Ω-RTR (dimensionless fall velocity-relative tide range) model is a widely recognised framework for classifying the geomorphic and dynamical states of beaches. Although this model does not explicitly predict the location, timing, and intensity of rip currents, it estimates the likelihood of rip currents forming at specific beach types. In this study, 33 representative touring beaches along the coasts of China were studied and the rip current risk of these beaches was evaluated with the Ω-RTR model. According to this classification, beaches can be categorised into eight types, seven of which are presented among the 33 Chinese beaches studied in this paper, and notably, the Ultra-Dissipative (UD) type is absent. The most common three beach types identified are Barred (B), Low Tide Bar/Rip (LTBR), and Non-Barred Dissipative (NBD). The former two are predominantly located in Shandong, Fujian, and Hainan provinces, while the latter is mainly found in Zhejiang, Fujian, and Guangxi provinces. The rip current risk across these beaches is primarily assessed as medium to high, with low-risk beaches primarily situated in Zhejiang, Fujian, and Guangxi provinces. There is minimal month-to-month variation in beach type and rip current risk along the Yellow Sea, Bohai Sea, the coast of Zhejiang Province, and the coasts of Hainan Island and Guangxi Province. However, notable seasonal variations in beach type and rip current risk are observed in Fujian Province. This study provides a comprehensive assessment of rip current risk across key coastal touring beaches in China. Additionally, it contributes to the expansion of data sources for the beach geomorphic-dynamical classification system. The findings offer valuable insights for enhancing the safety of beachgoers and promoting the sustainable development of China’s coastal tourism industry.