Research into rip currents may improve swimmer safety

8:42 pm on 2 February 2019

Researchers from the University of Canterbury are trying to better understand dangerous rip currents around New Zealand's coasts.

Sign on a beach resort warning of strong rip currents

Photo: 123RF

Each year, about five people die in rip currents, and surf lifeguards attribute about 85 percent of their rescues - about 700 each year - to the fast, offshore flows of water.

University of Canterbury coastal geomorphologist Seb Pitman is leading a team deployed at Muriwai Beach on Auckland's wild west coast where they are tracking the currents using GPS-enabled surf zone "drifters".

The drifters are designed to mimic someone floating in the water and the GPS provides information on current speed and circulation pattern.

"What we're really trying to pinpoint is the threshold at which wind, wave and tide conditions can all conspire to turn the rip current on or off," Dr Pitman said.

"By comparing current speeds and circulation patterns to the wave height, wind direction, and tidal stage, we can hope to come up with a predictive index for hazardous conditions."

The researchers hope that eventually they will be able to use their findings to provide better information to the public about beach hazards.

That could be integrated into the Auckland Council's Safeswim website and app, which provides real-time information about water quality at beaches around the region.

"The purpose is not to 'red flag' beaches and prevent their use, but simply to make people stop and think when they get to the beach," Dr Pitman said.

"If they arrive and a warning is shown about rip currents being particularly hazardous that day, they now have that information on hand to make an informed judgement on whether they really want to go into the water, and if they do, then to carefully consider where might be best to swim."

The research finishes in mid-February, and it is hoped the team will be able to develop a real-time hazard prediction system by next summer.

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