Lasers Watching San Diego Beaches

Where is all the sand going?

By Greg Bledsoe
|  Thursday, Jan 3, 2013  |  Updated 11:55 AM PDT
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How Scripps Institution of Oceanography researchers are using lasers to track grains of sand. NBC 7's Greg Bledsoe reports.

How Scripps Institution of Oceanography researchers are using lasers to track grains of sand. NBC 7's Greg Bledsoe reports.

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Researchers from Scripps Institute of Oceanography are using lasers to track where sand goes as it's washed off the beach.

Perched inside a temporary storage bin 20 feet above the beach Professor Bob Guza is looking for the change that always happen this time of year.

"Our beaches are seasonal, just like our weather," he says. "They are under increased stress. There's not enough sand."

The reasons the beaches are shrinking, he says, range from rising sea levels, to damming rivers, which starves the beach of new sediment, the main source of sand in southern California.

Guza and a team of scientists from Scripps Institute of Oceanography are measuring the movement of sand using lasers. Seven beams per second are fired 24 hours a day, with each and every wave that hits this shoreline. The lasers is on loan from the Army Corps of Engineers, and is unlike any tool these scientists have been able to use in the past.

"When it's high tide and the waves are coming up over the berm, we can watch how much sand each individual wave takes away," Guza said.

During the winter, larger surf strips sand from the beach, and then returns it during the summer.  Shrinking beaches are a threat to homes, businesses and tourism along the coast.

Over the past year, SANDAG spent more than $28 million to import sand onto eight local beaches in hopes of fighting beach erosion. This year, 89,000 cubic yards was dumped at Cardiff beach where the laser project is now monitoring.

Guza's team is trying to find out if it works, or if all that money is eventually just washed away.

"The question we're trying to answer is how long does the sand stay here, what are the conditions when it goes away, and how far does it go?" he said.

The team will be monitoring the sand through February and then has to return the laser. Guza said he hopes they can borrow it again in the future to study additional beaches.

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