Rip currents – strong channels of water flowing seaward from the shore – kill more Americans than do hurricanes. Caught off guard, people are swept out to sea, where they exhaust themselves swimming against the pull of the strong, outrushing current, and drown.
While scientists and the National Weather Service have made progress predicting the probability of rip currents in given locations, they so far lack a method ot accurately forecast whether and when they’ll actually occur, and how strong they might be.
Oregon State University’s Tuba Ozkan-Haller is hoping to change all that. For the last five years, she’s been working to develop a model to identify the location of rip currents up to a day in advance – something that would be a boon to swimmers, surfers and lifeguards around the world, and could save hundreds of lives a year.
Ozkan-Haller, an associate professor in OSU’s College of Earth, Ocean & Atmospheric Sciences, surveys the topography of the ocean floor to figure out how waves will travel over it; this allows her to see how that mass of water can escape back from shore via a rip current. She plugs these factors into a mathematical model she developed that predicts where and when rip currents will occur – and how strong they will be.
Helping her efforts are cutting-edge surveying technologies that allow her to observe properties at the water’s surface and infer the underlying bathymetry from those observations. This is a much more efficient and accurate way to get a sense of the sea floor than the standard procedure of surveying from a boat.
“I’m totally floored by how well we can do compared to traditional surveying methods,” says Ozkan-Haller. “You can set up a radar system near a beach and get continuous estimates of the bathymetry as it evolves from day to day without ever stepping foot into the water.”
The rip current effort is part of Ozkan-Haller’s broader interest in underwater coastal topography and how it helps shape the ocean’s waves. Oregon Sea Grant has supported some of that work, including a related project to develop a model for predicting nearshore wave patterns and heights. A reliable wave forecast system would benefit navigation, fishing, transportation, beach safety and even wave-energy siting.