Be Boundless

NSF grant funds transient rip current research


September 28, 2017

   Nirnimesh Kumar

Accomplishing two good deeds with one research project is the epitome of efficiency. With the goal of improving hazard forecasts for swimmers as well as determining the rate at which contaminants are spread into deeper waters, a team of researchers will investigate transient rip currents. In addition to transporting pollutants offshore, transient rip currents are one of the leading causes of fatalities on beaches.

Assistant professor Nirnimesh Kumar together with UW Applied Physics Lab research scientist Melissa Moulton have received a three-year National Science Foundation (NSF) grant funded by the Physical Oceanography Program, Division of Ocean Sciences. The research team also includes CEE graduate student Christine Baker. The project will build on Kumar’s existing research on the region of the ocean extending from the shoreline to a depth of 100 meters.

Unlike the more commonly understood rip currents, called “bathymetric rip currents,” the location of transient rip currents varies greatly and they seemingly occur at random. This makes them more difficult to measure and, as a result, they are not as extensively studied.

Previous research suggests that transient rip currents may be one of the primary ways that pollutants are transported offshore. The shoreline and the intertidal zone, which provide habitat for marine life, are often contaminated by pathogens and excess nutrient supply from storm water discharge and riverine runoff. This causes disruption to the marine habitats and often necessitates beach closures.

To better understand transient rip current induced circulation dynamics, the researchers will investigate the generation and transformation of transient rip currents at the directional wave basin at Oregon State University. They will create a set of random directional waves that, upon breaking, will generate surf zone eddies that may combine to form transient rip currents.

The researchers will use a combination of remote sensing and other instruments to evaluate rip current generation. Numerical models will be developed to further simulate and study three-dimensional characteristics of the rip currents.

To improve hazard forecasts at beaches, the researchers will collaborate with National Oceanic and Atmospheric Administration scientists. They also will participate in outreach activities through the O.H. Hinsdale Wave Research Laboratory Outreach Program, as well as work closely with scientists specializing in remote sensing measurements at the Naval Research Lab, Stennis Space Center, Mississippi.


To better understand transient rip current induced circulation dynamics, the researchers will use a combination of remote sensing and other instruments, as shown above.