Ocean Sciences Meeting Report

Forecasting and Communicating Risk of Rip Currents, Wave Runup

NOAA Coastal Hazards Resilience Workshop—Rip Currents and Wave Runup; Suffolk, Virginia, 14–16 April 2015

By , Andre van der Westhuysen, and Nicole P. Kurkowski

Rip currents and wave runup are common coastal processes that can have extreme negative consequences for life and property. Rip currents are relatively narrow seaward-directed jets of water that originate near the shore and are widely considered the greatest public safety hazard at the beach. Wave runup is the changing water level on the beach caused by breaking waves that can lead to significant erosion, overwash, and flooding.

A rip current on North Carolina’s Outer Banks. The rip current is visible in the center of the photograph where there is a flat spot in the line of breaking waves, and where foam is seen moving offshore. Credit: Gregory Dusek
A rip current on North Carolina’s Outer Banks. The rip current is visible in the center of the photograph where there is a flat spot in the line of breaking waves and where foam is seen moving offshore. Credit: Gregory Dusek

Although these two processes are distinct, they are both driven predominantly by wind-generated ocean waves. As such, they have the potential to be forecast through the use of high-resolution models.

The National Oceanic and Atmospheric Administration (NOAA) sponsored a workshop in April in Suffolk, Va., to develop strategies for instituting statistical forecast models for both rip currents and wave runup, with attention to the social science aspects of communicating the risk of these hazards. The workshop brought together approximately 80 experts representing all U.S. coasts and included NOAA forecasters and scientists, researchers from the U.S. Geological Survey and academia, representatives of the U.S. Lifesaving Association, lifeguards, emergency managers, and members of the media.

The workshop focused, in part, on strategies for nationwide implementation of an operational rip current forecast model, tests of which have been piloted by NOAA’s weather forecast offices in North Carolina’s Outer Banks and Miami, Fla. Participants discussed how to better collaborate with lifeguards to increase the reporting of rip current occurrences along with observations on their intensity. Attendees also discussed using camera-based observation systems to provide better quantitative estimates of both rip currents and surf zone bathymetry.

Other discussions conveyed the importance of evaluating present methodologies for communicating rip current forecasts and expected hazards. Many of the attendees stressed the need for a social science evaluation before any significant changes are made to national public safety messaging such as NOAA’s “Break the Grip of the Rip” campaign—the signs, magnets, and information posted at public beaches and hotels that spell out what to do if caught in a rip current. Focus groups at the meeting highlighted the importance of tailoring some aspects of risk communication to specific demographics, regions, or beaches.

Another focus of the workshop involved researchers’ efforts to develop wave runup models for various beach profile types, ranging from sandy beaches to those with hard structures like seawalls. Discussions emphasized the necessity of accurate beach slope information. Because beach slopes can have significant interstorm or seasonal variation, participants proposed applying uncertainty bounds to the slopes and resulting runup estimates on the basis of composites of historical survey data.

The discussion also included ways to communicate wave runup risk to emergency managers and the public. Attendees suggested producing information on the time-integrated risk of erosion, overwash, and inundation along entire coastlines on the basis of wave runup relative to the dune profile.

Outcomes of this workshop will include creating documents that assess what scientists need before they can improve rip current forecasts and platforms for information dissemination, devising strategies for expanding the NOAA rip current forecast model from the mentioned pilot sites to additional weather forecast offices, and identifying enhancements to an ongoing NOAA-led rip current observing project. Furthermore, a strategy will be developed to expand wave runup applications from weather forecast offices along the U.S. northeast coast to include southeast coasts and other areas.

A more complete overview of the workshop, along with links to the agenda and the presenter list, can be found in a PDF version of this report.

—Gregory Dusek, Center for Operational Oceanographic Products and Services, National Ocean Service, National Oceanic and Atmospheric Administration (NOAA), Silver Spring, Md.; email: [email protected]; Andre van der Westhuysen, I. M. Systems Group, Inc. at National Centers for Environmental Prediction, National Weather Service, NOAA, College Park, Md.; and Nicole P. Kurkowski, Office of Science and Technology Integration, National Weather Service, NOAA, Silver Spring, Md.

Citation: Dusek, G., A. van der Westhuysen, and N. P. Kurkowski (2015), Forecasting and communicating risk of rip currents, wave runup, Eos, 96, doi:10.1029/2015EO034461. Published on 20 August 2015.

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