Rip currents and beach hazards: their impact on public safety and implications for coastal management

Abstract

Beach hazards are traditionally associated with damage to structures, property and the environment. In this paper, however, we address every day beach conditions including surf zone topography, water depth, waves and rip currents that in Australia annually result in up to 50 drownings and over 10,000 rescues. Using the Wright and Short (1984) beach model, the morphodynamics and bathing hazards associated with each of the six beach states are identified and the states rated accordingly from the safest (1) to least safe (10). The rating is then used to grade all 721 ocean beaches along the New South Wales coast. Seventy percent of the beaches are dominated by rip currents with 61% of all beaches rating 5 and higher. A survey of several hundred beach rescues on these same beaches found that 89% occurred in rips. Finally, field experiments during average wave conditions verified the speed at which rip currents can transport bathers rapidly beyond the surf zone into deep water. The level of public beach risk was then assessed using the beach safety rating in combination with the level of beach usage. Coastal management policies need to be cognisant of the relationship between beach type, beach usage and public beach risk. This can be achieved by coastal management policies that consider the impact coastal development has in increasing beach usage and thereby the level of public risk on adjacent beaches, and the allocation of appropriate beach safety resources to mitigate this risk.