EAPSI: Evaluating Beachgoer Vulnerability to the Rip Current Hazard

Trimble Sarah M, College Station TX

Investigators

Abstract

Rip currents are strong, narrow seaward flows of water that originate in the surf zones of many global beaches. They are related to hundreds of international drownings each year, but exact numbers are difficult to calculate due to logistical difficulties in obtaining accurate incident reports. Annual average rip current fatalities are estimated to be ~100, 53 and 21in the United States (US), Costa Rica, and Australia respectively. While physical rip current behavior is relatively well understood, we know little about the social aspect of rip current hazards. Recent research shows that beachgoers drown from a combination of physical and social factors, with the latter related to beachgoer age, swimming ability, knowledge, and ability to spot a rip. The rip current hazard has been exacerbated by information disconnects between three groups: beach scientists, beach safety practitioners, and the general public. This project will use a mixed-methods approach to address these disconnects by combining novel methods of measuring rip current channel morphology and measured beachgoer knowledge to determine behavior from subject proximity to rip current channels. Results will help improve design of rip current education interventions in Australia, the United States and globally. The project will be overseen by Dr. Rob Brander, Associate Professor at the University of New South Wales and noted rip current expert. Interviews will be analyzed for spatial relationships to rip hazard locations, as determined from bathymetric maps that will be created from multispectral imagery captured by Digital Globe?s WorldView2 (WV2) satellite. The depth of penetration for different bands of the electromagnetic spectrum captured by this satellite can be used to derive bathymetry. Because rips form in topographic lows in bathymetry, their location can be interpreted from channels in the surf zone. This method has the highest accuracy in clear waters like those around Sydney. Rip locations, combined with interview results and locations, will determine if subjects? observed behavior (choice in location within a beach) reflects their knowledge of beach dynamics. Results of this study will clarify how gaps between coastal geomorphologists, policy makers, and beachgoers can be bridged to lower rip-current related fatalities and injuries in Australia and the United States (US). This NSF EAPSI award is funded in collaboration with the Australian Academy of Science.