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Efforts to study crumbling Del Mar cliffs advance as UCSD Scripps deploys state-of-the-art wave buoy

Andrew Gray, left, Les Hanson, and Victor Aguilar of UC San Diego’s Coastal Data Information Program hoist a wave buoy into the ocean off the coast of Del Mar on Dec. 5, 2019. The buoy measures wave heights and current patterns near the area where bluffs have collapsed.
(K.C. Alfred/The San Diego Union-Tribune)

Scientists at UC San Diego’s Scripps Institution of Oceanography just received a major new tool in trying to decipher the patterns of erosion eating away at the crumbling Del Mar bluffs, atop which passenger trains regularly run up and down the coast.

A team from the Coastal Data Information Program at Scripps recently deployed one of the world’s most sophisticated buoys for measuring waves. Among other things, the device will record the height and direction of ocean waves about a mile off the city’s receding coast, providing real-time data to everyone from scientists to surfers.

“Having the buoys out there is really important for all different types of studies including cliff and beach erosion and tracking changes across our coastline,” said Adam Young, a Scripps researcher who has been studying cliff erosion in Del Mar and around the state.

Les Hanson, left, and Jim Behrens of the Coastal Data Information Program make final adjustments on a wave buoy off the coast of Del Mar on Dec. 5, 2019. The buoy measures wave heights and current patterns near the area where bluffs have collapsed.
(K.C. Alfred / The San Diego Union-Tribune)

About a week ago, train service was temporarily halted after a section of the cliffside south of Seagrove Park crumbed within several feet of the tracks. Transportation officials have been monitoring the area closely around the clock.

A crew from Scripps spent Thursday morning, Dec. 5, deploying the yellow wave buoy, departing from Nimitz Marine Facility in Point Loma and cruising up the coast in the R/V Bob and Betty Beyster, a 42-foot scientific research vessel built for near-shore activity and speed.

Once at the location, the ship’s captain, Brett Pickering, navigated around lobster traps looking for a good spot to drop the buoy and its anchor. The crew readied themselves for the delicate task of getting the 500-pound device into the ocean.

“We don’t want to drop the anchor first because if you throw all this line in the water really fast, it has the possibility of taking somebody with it,” explained Andrew Gray, field manager for the Coastal Data Information Program, who led the process.

Gray attached the buoy to a winch mounted on an A-frame on the back of the vessel. “Winch up,” he called to Pickering, and after some maneuvering, the crew carefully lowered the device into the water.

Once they dropped in the anchor, members of the crew put on scuba gear and dove down about 60 feet to inspect their work.

Researchers largely use wave models to study coastal impacts, but checking those calculations against direct observations from the buoys greatly enhances accuracy, said Eric Terrill director of Coastal Observing Research and Development Center at Scripps.

“The buoys are great,” he said. “Our ability to use modeling to forecast waves is still severely limited with a lot of errors. Putting these buoys in areas of extreme importance like Del Mar gives us another validation point.

“We needed to have observations of the waves off Del Mar because of the situation with the sand-starved beaches and the critical infrastructure of the train tracks,” he added. “Having the measurement will allow us to do a much better job of forecasting change.”

The Amtrak Surfliner train heads north along the tracks in Del Mar where bluffs toward the ocean regularly collapse on Dec. 5, 2019.
(K.C. Alfred / The San Diego Union-Tribune)

The new buoy location is one of about 70 in United States waters, from San Diego to Alaska, across the eastern seaboard, the Gulf of Mexico, Hawaii and the South Pacific.

The real-time data is available to the public at cdip.ucsd.edu and used by everyone from the Navy to Coast Guard to shipping companies in the Port of Long Beach. San Diego Lifeguard Services also regularly use the devices.

“It has been vital for coastal projects, including repairs to the Ocean Beach Pier, and understanding the historical data around king tides and high wave activity,” said Lifeguard Division Chief James Gartland.

The Scripps program has seven buoy stations in the San Diego region, including in Point Loma, Mission Bay, La Jolla, Imperial Beach, Torrey Pines and Oceanside.

“We have completely open access to very high-precision, quality-controlled data,” James Behrens, who manages the Coastal Data Information Program at Scripps, said during the Dec. 5 trip.

Gray added that the device will also likely be popular with local surfers. “They’re going to love this,” he said, adding, “One of my favorite things about this job is a lot of the feedback you get from users.”

In January, Scripps researchers used an experimental warning system to successfully predict a massive flooding event in Imperial Beach that was developed in part using the buoy data. As a result, city officials and residents were better able to brace for the impacts.

The buoy data has been used to help predict flooding on the East Coast as well, measuring massive wave heights even during hurricanes. For example, during Hurricane Florence last year in the Carolinas, waves were recorded of more than 47 feet.

Last month, a buoy off the coast of Cape Mendocino in Humboldt County measured a wave of 75 feet, one of the largest in recorded history, according to Scripps officials.

“It’s a real privilege to come shine a light on one part of the environment and provide real information for society,” Behrens said. “It’s a motivating factor for us, and it’s a guiding principle that everything we do we share with the public in real time.”

Scientists are also using the buoys to better understand how waves move sand and sediment around on beaches, a key factor in determining erosion along the region’s narrow coast lines. The U.S. Army Corps of Engineers, who funded the most recent deployment in Del Mar, is keenly interested in better understanding this process, Behrens said.

“The Army Corps is responsible for setting design standards and thresholds for coastal construction,” he said. “If you’re going to put in a pier, put a road in along the coast, the Army Corps will provide the baseline engineering requirements to make sure things are safe.”

The roughly $70,000, solar-powered buoy in Del Mar is estimated to last about three years and will require an ongoing annual maintenance and operation budget of about $2 million, according to Scripps officials.

The Scripps program dates to 1975. The buoys are built by a Dutch company called Datawell.

— Joshua Emerson Smith is a reporter for The San Diego Union-Tribune


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