Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Characteristics and factors of beach safety accidents: A case study from Dadonghai beach, China
Yanzhe Chen, Yuan Li, Jian Shi, Chi Zhang

College of Harbour, Coastal and Offshore Engineering, Hohai University.
Nanjing, Jiangsu Province, China

ABSTRACT

Australia, 89% of beach rescues (over 25,000 per year) performed bylifeguards and surfers are caused by rip currents (Short and Hogan, 1994;
Sherker et al., 2008; SLSA, 2011). Castelle et al. (2018) found the shorebreak wave is the main cause (44.6%) of coastal injuries in southwesternof France. Similar results were also reported by Muller (2018) that 82%
of coastal injuries were caused by shore-break waves in Ocean City,Maryland, from 2006 to 2015.

Data on beach accidents on the Dadonghai from 2004 to 2021 wascollected by conducting a web search. The data collected includes thetime of the accident, the number of people involved, their age, gender,
place of origin and the activities they were doing at the time of theaccident. During this period, there were 38 beach safety accidents
involving a total of 112 people, of which 28 were fatal. Compared to theNational Beach Safety Database of China, the accidents wereconcentrated in the summer months (i.e., June, July and August) when
there is a high volume of tourists, with an average of 2.9 persons
involved in a single accident, compared to 1.8 persons involved inaccidents in the database. The majority of accidents occurred between
the hours of 15:00 to 18:00 and 18:00 to 21:00. A comparison ofdemographic characteristics revealed that the largest proportion ofaccidents occurred between 18 and 24 years old (36%), followed by 7 to
17 years old (27%). In terms of gender, the number of males wasapproximately five folds larger than that of females. With respect to theplace of origin of the tourists involved in the accidents, 68% were notrecorded, and in terms of the total number, 27% of the injured were outof-town. The morphology of Dadonghai beach is analyzed, a steep beachslope of 1/20 is found, which is likely to trigger shore-breaks and drive
wave-induced currents near the shoreline. Based on Satellite images, 4remarkable rip current channels are found, indicating the high risk of rip
current on this beach.

There are hundreds of beaches along China's 18,000 kilometers ofcoastline. Dadonghai beach in Sanya City, Hainan Province is one of themost popular coastal tourist areas in tropical China, attracting a large
number of tourists domestic and international. The length of Dadonghaibeach is about 1.4 km. According to statistics, the number of tourists
received every day reaches 20,000 to 50,000 in peak season. There arealso 4000 tourists per day in the off-season, with a very high proportionof international tourists. With such a large number of tourists, the risk
factor of beach hazards to tourists is also higher. Beach safety accidents
occur every year at Dadonghai beach. According to the lifeguards, about
300 tourists are rescued from the water every year, and many media
reports on the accidents in the Dadonghai beach have referred to thebeach as a "life-threatening beach". Li and Zhu (2018) studied the risk
assessment of rip currents at the Dadonghai beach and found that thehigh-incidence period of beach safety accidents on Dadonghai beachcoincides with the high-risk period of rip currents.
So far, studies regarding the safety of tourists on the beach in China isscarce. In this study, we conduct a systematic statistical and analysis ofbeach safety accidents and characteristics from 2004 to 2021 at
Dadonghai beach, and also combine the morphology-relatedcharacteristics of Dadonghai beach to analyze the characteristics ofsafety accidents and morphological impacts at Dadonghai beach.

KEY WORDS: Beach safety; coastal disasters; rip currents; shorebreak waves; beach morphology.

INTRODUCTION
Beaches, as a location in every coastal country, are visited by many
tourists from all over the world, whether they are tourist beaches
managed by the relevant authorities or unmanaged natural wild beaches.
However, there are always dangers at every turn when playing at thebeach. Due to the complex bathymetry of many beaches, which arecontrolled by waves, tides, currents and morphology, there are manypotential safety hazards. According to national and international research,
the greatest threat to beachgoers is the presence of rip currents and shorebreak waves. According to the U.S. Lifesaving Society, over 80% ofbeach rescues in the U.S. are caused by rip currents each year (USLA,2012; Brewster and Gould, 2014; Lascody, 1998; Lushine, 1991), and in

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METHODSThis study collected data by a web search, and preliminarily collected
the safety accident data of Dadonghai beach tourists from 2004 to 2021
through keywords such as "Dadonghai" and "drowning". Taking any
point on the 1 m water depth contour line near the rip channels in the
middle of the beach, and extending it to the 2.5 m contour line along thedirection perpendicular to the beach shoreline to the land direction. By
calculating the horizontal distance and elevation difference of the point
to the 2.5 m contour line, it can be used to calculate the approximate