Experiment to put surf lifeguard in Raglan rips

Media Release 18 January 2008 NIWA

Experiment to put surf lifeguard in Raglan rips

Scientists from the National Institute of Water & Atmospheric Research (NIWA) are undertaking a unique experiment with Surf Life Saving New Zealand to investigate the behaviour of rips. The experiment, scheduled for 22 January, will follow a surf lifeguard carried along by rips at Raglan beach.

Senior lifeguard Nathan Hight, Lifesaving Development Manager at Surf Life Saving New Zealand (SLSNZ), will be repeatedly placed in rips at Raglan to see how fast he travels in different tide and wave conditions. In one trial, he'll be left floating in the rip to see how far a body can go since its last sighting. NIWA scientists onshore will track his speed and position using a GPS satellite tracking device attached to his helmet, and NIWA's Cam-Era video beach monitoring system.

"The data we collect will be used to calibrate our models of how rips form and behave and ultimately assist surf lifeguards in rescuing people and recovering bodies caught in rips," says NIWA coastal scientist Terry Hume. "We have a good handle on why and how rip channels form, but we lack good information on the speed of the water at the surface where people get caught," says Dr Hume.

In the long-run, the information will be used to predict the likelihood of rips developing, which will be incorporated into a beach hazard rating for all New Zealand beaches that Surf Life Saving New Zealand is developing with help from NIWA. NIWA is working on ways to forecast rips using offshore wave forecasts and the positions of sandbars identified by the Cam-Era video beach monitoring system.

As for the danger, Surf Life Saving New Zealand Lifesaving Manager Brett Sullivan says they're taking all safety precautions for this experiment. "Surf lifeguards regularly use rips to get out quickly to victims and are specifically trained to handle them. The information gained in this experiment will hopefully enable lifeguards to better understand rips and more accurately pinpoint victims in their rescue and recovery operations."

The research is funded by the Foundation for Science, Research & Technology.

Media Please Note: The experiment is dependent on getting big enough waves. It is due to start around 10:00 hours on Tuesday 22 January, but the best waves conditions, based on NIWA's wave forecast model, are expected from midday onwards. It will take place on Raglan Beach, based at the Raglan Surf Lifesaving Club.

What is a rip?

A rip is an offshore current concentrated in a narrow channel – like a jet of water – that flows faster than your average swimmer can handle, up to speeds of 2 metres per second. Rips are formed by a combination of big waves and the shape and position of sandbars, which influence how the tide interacts with the waves.

Rip currents can be recognised as the calm areas (blue water) between patches of breaking waves (white water)

Download the NIWA Natural Hazards rip current poster in English or Māori from: http://www.naturalhazards.net.nz/research/posters

What safety precautions are being taken? Mr Hight, an experienced surf lifeguard, will be wearing a wetsuit, helmet, and carrying a 'rescue tube' for flotation. He will be followed by a fully-equipped safety boat and closely watched by surf lifeguards in the Raglan Surf Lifesaving Patrol, who will be in radio contact with the safety boat.

How will the data be used? Data from the GPS tracking device will be used to calculate current speeds, both in the rip feeder and the rip itself. This will be linked to realtime information on the position of sandbars, from the Cam-Era system, and wave height, period, and direction from NIWA's Wave Forecasting Model. The data will be used to improve models of rip current formation and behaviour being developed by NIWA coastal scientist Dr Giovanni Coco, who is leading the experiment, with colleagues Dr Nicholas Dodd (University of Nottingham) and Dr Daniel Calvete (University of Barcelona), and Dr Karen Bryan from Waikato University.

NIWA's wave forecasting service http://www.niwa.co.nz/ncco/forecast

NIWA's rip forecasting research http://www.niwa.co.nz/services/free/cam-era/rip

NIWA's Cam-Era project NIWA runs 12 fixed video cameras at beaches around the country. These are computer-controlled for realtime coastal monitoring of currents (including rips) in relation to wave height and the position of sandbars. The data is used for research purposes. Images are updated hourly on the website for public use. See: http://www.niwa.co.nz/services/free/cam-era/about

The Raglan Cam-Era system involves two cameras set up in 2007 with funding from Environment Waikato.

Latest Cam-Era images of Raglan Beach: http://www.niwa.co.nz/services/free/cam-era/raglana http://www.niwa.co.nz/services/free/cam-era/raglanb

What to do in a rip (advice from Surf Life Saving New Zealand) DON'T try to swim against it. If you are a capable swimmer, swim sideways out of it. Otherwise, go with it until it dissipates (usually about 100m along), then swim across the beach for about 50-100m until you're in the surf zone, which will help bring you back into the beach. STAY CALM – panic tires you out.

(see rip eduction poster for kids at http://www.slsnz.org.nz/Article.aspx?Id=1090)

Some beach and surf lifesaving statistics (from Surf Life Saving New Zealand) • 2.5 million kiwis go to the beach every year. • There are 71 surf lifesaving clubs operating in New Zealand. • Surf lifeguards currently patrol about 80 beaches (about 3% of New Zealand's coastline) and provide a callout service to other areas. • 17 people drowned on New Zealand surf beaches in 2007 (out of 110 drownings)

Beach hazard ratings

Surf Life Saving New Zealand and NIWA are currently adapting an Australian beach hazard rating system for New Zealand beaches. The rating is on a 10-point scale and incorporates such factors as: the number of rips, wave action and height, and topography (including the presence of rocks and reefs). Beach hazard ratings are expected to be available in June 2008. The average hazard rating for Raglan beach currently stands at 8/10.

Surf Life Saving New Zealand: http://www.slsnz.org.nz/

ENDS

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