Evaluation of swimmer-based rip current escape strategies

McCarroll, Joshua A.; Brander, Robert W.; MacMahan, Jamie; Turner, Ian L.; Reniers, Ad; Brown, Jennifer; Bradstreet, Anthony; Sherker, Shauna

doi:10.1007/s11069-013-0979-1

Cited by 61 publications

(75 citation statements)

References 43 publications

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“…Austin et al 2013;Castelle and Coco 2013;Houser et al 2013;Scott et al 2014;Winter et al 2014;McCarroll et al 2014b), and hence floating may not be as viable a strategy as initially proposed. Extensive testing of the different bather escape strategies was first conducted by McCarroll et al (2014a) across three rip current systems comprising two open beach rip currents featuring TBR morphology, and a topographic rip current adjacent to a shore platform. Floating generally resulted in longer times to safety with higher variability compared to swimming parallel, but also noted that neither strategy was 100 % successful.…”

Section: Introductionmentioning

confidence: 99%

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Examining rip current escape strategies in non-traditional beach morphologies

et al. 2015

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Rip currents are a significant hazard on global surf beaches and are a factor in hundreds of drowning fatalities each year. Contemporary rip current safety information often idealises rip currents as part of a Transverse Bar Rip (TBR) morphology with rip channels bound by shallow, shore-connected bars. Real-world conditions frequently differ from this model, with potential implications for rip current escape strategies promoted to, and undertaken by, the general public. This study describes outcomes of rip current escape strategies conducted at North Cronulla Beach, NSW, Australia, over two distinct morphologies; a mixed Low Tide Terrace/Transverse Bar Rip (LTT/TBR) and a Rhythmic Bar Beach (RBB) system lacking shore-connected bars. Swimmers attempted to escape by adopting one of three pre-determined strategies: Stay Afloat, Swim Parallel and Swim Onshore. A total of 100 escape attempts were conducted, with the RBB system experiencing longer duration ( t = 2.4 min) escapes than the LTT system ( t = 0.8 min). The RBB system was associated with a higher rate of action failure, particularly for Stay Afloat, due to a lack of shore connectivity of adjacent bars. Swim Parallel was of lower duration ( t RIP1 = 0.66, t RIP2 = 2.68 min) in both systems, but durations and distances to safety in the RBB system often exceeded swimming abilities of weaker bathers. Although Swim Onshore was more successful ( t RIP1 = 0.22, t RIP2 = 1.65 min) than Swim Parallel, promotion of such a strategy is strongly discouraged in conventional safety advice. Results suggest that contemporary rip current escape strategies may be inappropriate in non-TBR rip current systems and that alternative strategies should be considered, including Swim Onshore and a greater focus on preventative strategies, particularly in relation to bathers with limited swimming ability.

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Section: Introductionmentioning

confidence: 99%

“…How this relates to swimmer escape behaviour is unknown, as existing studies (e.g. Miloshis and Stephenson, 2011;McCarroll et al 2014a) have been conducted in TBR-type rip current systems.…”

Section: Introductionmentioning

confidence: 99%

Examining rip current escape strategies in non-traditional beach morphologies

et al. 2015

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“…A large proportion of rip current videos referred to multiple rip escape strategies such as an active swim action (e.g., swimming parallel to the beach) and a passive float action (e.g., go with the flow). While this could be considered potentially contradictory and confusing to viewers, recent research on rip current escape strategies and responses of people caught in rip currents have highlighted the unpredictability and variability of rip current flow and bather response (Drozdzewski et al, 2012;Drozdzewski, Roberts, Dominey-Howes, & Brander, 2015;McCarroll et al, 2014McCarroll et al, , 2015Van Leeuwen et al, 2016). This, in turn, has influenced Surf Life Saving Australia, Australia's largest beach safety organization, to adopt and communicate a "combined approach" message to the general public regarding how to react when caught in a rip current (Bradstreet et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

YouTube Videos and the Rip Current Hazard: Swimming in a Sea of (Mis)information

Mackellar¹,

Brander²,

Shaw³

2015

IJARE

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“…The GPS used on the 2013 Katama drifters is a Locosys GT-31, which provides accurate relative position useful for velocity measurements. The Locosys GPS has successfully measured surfzone velocities and trajectories (McCarroll et al, 2014) and surface gravity wave elevations (Herbers et al, 2012). The inlet drifters were also deployed as part of an experiment in the inner shelf of the Gulf of Mexico.…”

Section: Drifter Observations In 2013mentioning

confidence: 99%

Assimilating Lagrangian data for parameter estimation in a multiple-inlet system

et al. 2017

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Numerical models of ocean circulation often depend on parameters that must be tuned to match either results from laboratory experiments or field observations. This study demonstrates that an initial, suboptimal estimate of a parameter in a model of a small bay can be improved by assimilating observations of trajectories of passive drifters. The parameter of interest is the Manning's n coefficient of friction in a small inlet of the bay, which had been tuned to match velocity observations from 2011. In 2013, the geometry of the inlet had changed, and the friction parameter was no longer optimal. Results from synthetic experiments demonstrate that assimilation of drifter trajectories improves the estimate of n, both when the drifters are located in the same region as the parameter of interest and when the drifters are located in a different region of the bay. Real drifter trajectories from field experiments in 2013 also are assimilated, and results are compared with velocity observations. When the real drifters are located away from the region of interest, the results depend on the time interval (with respect to the full available trajectories) over which assimilation is performed. When the drifters are in the same region as the parameter of interest, the value of n estimated with assimilation yields improved estimates of velocity throughout the bay.

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Evaluation of swimmer-based rip current escape strategies

Cited by 61 publications

References 43 publications

Examining rip current escape strategies in non-traditional beach morphologies

Examining rip current escape strategies in non-traditional beach morphologies

YouTube Videos and the Rip Current Hazard: Swimming in a Sea of (Mis)information

Assimilating Lagrangian data for parameter estimation in a multiple-inlet system

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