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The University of Plymouth has teamed up with the RNLI to carry out a world-leading scientific investigation into the phenomena of rip currents. Scientists from the University will work alongside lifeguards at Perranporth beach in North Cornwall using video, GPS devices and current meters to measure rip current speeds and directions under a wide range of wave and tide conditions. This data will then be integrated into a predictive model that can be applied to UK beaches to forecast when and where potentially dangerous rip currents will occur.
Project leader Professor Gerd Masselink, of the University’s School of Marine Science and Engineering, said: “We know what rip currents are, but we do not fully understand what controls their flow strength and pattern. Our understanding is particularly poor for rip currents on beaches with a large tide range. Practically all beaches in the UK are characterised by a large tidal range and if rip currents are present their activity, and therefore the hazard they present, strongly depends on the tidal stage.”
Dr Tim Scott, a research scientist on the project, identified through his RNLI-funded PhD research that rip currents typically account for over two thirds of the environment-related incidents that RNLI lifeguards respond to on some of the UK’s busiest beaches each season. The results of this investigation will not only improve understanding of rip currents, but will also lead to improved lifeguard training, safety advice and logistical planning for the RNLI, who are responsible for more than 140 beaches in the UK.
The University has set up video cameras which will take regular snapshots of the shoreline to build a picture of the pattern of wave breaking and sandbar locations. This will be combined with tidal levels and wave conditions and used to drive a computer model – known as Beach Wizard – to predict rip current activity at different times of the day and at different locations on the beach.
During two six-week fieldwork experiments in May and September 2011, the research team will repeatedly deploy 30 specialised GPS ‘drifters that mimic the movement of a floating swimmer and measure the speed and direction of the journey the drifters take. Additionally, current meters and wave measuring devices at ten locations in the surf zone will record current velocity over different tide cycles. The results from the fieldwork will feed into the Beach Wizard computer model to enable it to predict how the beach will behave at different times.
Paul Russell, Thurso.. back in the day. Photo John Conway
Professor Paul Russell, of the University’s School of Marine Science and Engineering, and a former European surfing champion himself, said: “Experienced surfers and lifeguards develop a practical knowledge of rip currents. By working with the RNLI in the field, we can gather the evidence that will enable us to develop a computer model that can predict the rip flow pattern for any given wave, tide and beach condition. If this proves a success, we will be able to apply the model to beaches across the country, giving advanced warning to the RNLI of when and where rips are likely to be most dangerous.”
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