A morphology-based drowning risk index for rock platform fishing: a case study from southeastern Australia

There has been an increase in drownings over recent decades in Australia, particularly among rock fishers swept from the edge of rock platforms. Platform morphology is central to understanding what makes one stretch of coastline more hazardous than another. This paper describes the development of an easily replicable site-specific risk index for rock platforms along the Illawarra coast, southeastern Australia. It can be applied to other microtidal wave-dominated coasts where airborne topographic LiDAR data are available, without requiring nearshore bathymetric data. The index is designed to assess the relative risk of being washed into the sea and will assist coastal managers in an effort to reduce the number of injuries and drowning incidents. The approach is based on subdivision of the terrestrial seaward edge of platforms into segments, classified according to mean elevation, orientation and edge type, to model different hazard scenarios. These are combined with the popularity of individual fishing locations, assessed during fieldwork, to estimate risk. Results of 620 segments from 26 rock platforms indicate that most of these platforms lie above high tide level and that approximately 3/4 of them are of type A (ramped) edge morphology and oriented at an angle facing northeast to southeast quadrants. The most hazardous segments for southeasterly wave scenarios are concentrated along sections of the platforms between Coalcliff and Austinmer, Woonona, Port Kembla south and Red Point. The southern sections of Red Point platform were considered the most risky of all due to fishing popularity.