A collaboration between the NSRI, the City of Cape Town and the South African Weather Service aims to develop a rip-current-risk forecasting system to enable safety personnel to better prepare for hazardous beach conditions.
Understanding rip currents
NSRI volunteers and municipal lifeguards have responded to countless callouts involving people caught in rip currents. In an attempt to better understand and predict rip currents, the NSRI teamed with the City of Cape Town’s Recreation and Parks Department and the South African Weather Service (SAWS) to study rip currents in a more scientific way. The idea is to develop educational material based on aerial footage of rip currents in False Bay and Table Bay. The recent experiments, conducted using fluorescein dye, will form part of an ongoing study by SAWS to develop an operational rip forecast model.
Making rip currents visible
The team was given permission by the National Department of Forestry, Fisheries and the Environment (DFFE) to use fluorescein dye, following global best practice among ocean researchers. Fluorescein dye, a non-toxic medium commonly used by research scientists in water-tracer experiments, is non-toxic to humans, animals and the environment. Releasing the dye into the water is a brilliant way to highlight and visually expose rip currents. The subsequent footage can then be used as part of a focused beach safety public awareness campaign in preparation for the summer season.
“The first dye release took place in September in Kogel Bay and, after studying the results from this experiment, we decided to film the second release at Dappat se Gat and again at Kogel Bay,” explains NSRI’s Drowning Department Manager Andrew Ingram.
Using the South African Weather Service’s experimental rip current forecast model, along with their standard operational coastal forecast systems, the rip current research team identified a strong likelihood that rip current would occur here on Wednesday, 20 October and chose this as the planned day for the second release.
Watch the video here:
SAWS’s rip current forecast model
Marine Unit Scientist Carla-Louise Ramjukadh, who is based at SAWS’s Cape Town Weather Office, explains that the pilot operation rip forecast model is housed and run by the SAWS’s Marine Unit. The unit had forecast the optimal days for the dye release on various beaches along the Cape Peninsula.
“Many different components were needed to build the operational rip forecast model for the Cape Peninsula coastline,’ she explains. “These were assembled via the input and expertise of many different project partners in South Africa, in conjunction with the Coastal Applied Research (CMAR) group in the UK, and through the Weather and Climate Science for Service Partnerships (WCSSPA) fund. (The WCSSPA is a collaborative initiative between research institutes in the UK and South Africa.)
“The pilot operational rip forecast model is currently in the testing phase to properly ensure sufficient performance. Every day, routine hydrodynamic conditions for a three-day forecast period are assessed, generating a rip risk forecast of the potential rip risk at six different locations across the Cape Peninsula coastline.”
The value of such a forecasting system is that it will enable public safety personnel to better prepare for hazardous beach conditions and inform the public of potential danger before they head out to the beach.
When enjoying a day out at the beach, follow the lifeguards instructions and swim in the safe zones they have flagged. If you find yourself caught in a rip current, try not to panic or swim against the current. You will become exhausted. Try, instead, to swim sideways out of the current and then head to shore. If you can’t escape, float or tread water. Try to preserve your energy and draw attention by calling for help or waving your arms for assistance.
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