Beach safe: Waikato research student aims to predict rips

Even after looking at literally millions of photographs of waves for two years, University of Waikato Masters student Shari Gallop admits she finds it difficult to pick a rip when she’s at the beach.

“I still struggle,” says the former Edgecumbe College student, who’s researching the link between wave patterns and the rip currents they create.

“You can see it better if you’re up on a hill, but as a rule of thumb you should aim to swim in the white water – that’s the safe space.”

Drowning is the third-biggest cause of death in NZ, and there’s been heightened awareness of the dangers of rip currents after Warriors player Sonny Fai was swept away by a current at a West Auckland beach last month.

To help understand rips better, Ms Gallop has created a computer programme to automatically locate rip currents in wave patterns off the Coromandel coast. She’s worked with more than three years’ worth of images relayed back every second from a camera overlooking Tairua beach.

“There’s a big debate over how rips relate to waves,” she says.

“Part of the problem is that most researchers compare snapshots of waves and rips, but that doesn’t tell us anything about how a particular wave pattern affects rip currents over time.

“We’ve gone a bit further and focussed on changes in rip behaviour, and compared those changes to wave conditions. Using the computer programme I’ve written, you can locate where rips are and track them through time.”

It’s taken Ms Gallop eight months of solid programming, but the initial results are promising. The aim now, she says, is to use the programme to predict rip currents – where they might form, how many and how strong they might be.

“It’s early stages yet, but ultimately we hope to create a workable tool which will help beach goers and surf life savers.”

Ms Gallop’s work is part of a joint project between the University of Waikato and the National Institute of Water and Atmospheric Research.

Academic supervisor Dr Karin Bryan of the University’s Earth and Ocean Sciences Department says Ms Gallop’s research has solved one of the great difficulties in the field: how to get proper data on such elusive things as waves.

“We’ve desperately needed this data to test our models for predicting the danger associated with rip currents,” says Dr Bryan.

“As a parent, I am delighted that Shari is putting her math, computer and oceanography skills together in such a clever way to solve a problem that often costs children’s lives.”