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Projected El Niño winter could double rate of erosion at San Francisco's Ocean Beach

Erosion at San Francisco's Ocean Beach could increase dramatically in El Niño winter 02:04

SAN FRANCISCO -- Parts of Ocean Beach are disappearing because of shifting sands and rising sea levels. 

Extreme El Niño conditions and strong wave forces can speed up erosion at twice the normal rate, according to researchers at USGS.

Scientists have been documenting the changes over the years, and why it's so crucial to produce accurate maps of the ever-changing beach. 

Daniel Hoover and a team at the United States Geological Survey are mapping Ocean Beach as part of monthly on-the-ground surveys. 

It's one of the most studied beaches by the agency because of how quickly it's changing. Using ATVs equipped with scientific grade GPS devices, the machines collect data.

"The redline is the Great Highway and Cliff House is right here. We use this to keep track of where we've been to make sure line density is adequate to give us the data we need," said Hoover.  

That data is used to generate 3-D maps that can show how far the beach is being pushed back by rising sea levels and the depth of sand, accurate to one inch. 

"These data we're collecting today will help us understand how great we're doing with those models and how they can be fine tuned and improved moving forward," said USGS geographer Amy Foxgrover. 

Accurate mapping helps city planners counter erosion impacts on neighborhoods and facilities like the waste treatment plant at the south end of Ocean Beach. 

Crews have built massive sand berms and rock walls to protect the aging structure.

"If erosion were to eat in and under the road and cause the pipe to rupture it would leak raw sewage into the ocean," said Hoover. 

"These data help them to know if they need more emergency measures which they've already done to protect the pipe," said Hoover. 

Scientists predict a moderate to possibly extreme El Niño winter, where high wave energy can wreak havoc, causing massive flooding and other problems.  

"El Niño is the big bully in terms of beach erosion," said Hoover. 

In fact, the last El Niño winter of 2015 and beginning of 2016 was in the top 3 in 150 years of record keeping. The concern is what could be around the corner after strong winter storm impacts from just a year ago. 

"It got hit pretty hard last winter. So it's starting from a relatively depleted state so areas that would have wanted more buffers won't have them this year.  If we have bigger waves this winter there could be some issues in some places," said Hoover.  

Mother nature can't be controlled, but scientists like Hoover at USGS are doing what they can to better predict its next move and impacts. 

USGS teams also conduct regular surveys using small planes and satellites but these on-the-ground surveys ultimately provide better resolution and accuracy for researchers.

Earlier this year, a USGS study showed that by the end of the century, close to three-quarters of California's beaches could disappear due to climate change and rising sea levels.

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