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Study Predicts Significant Southern California Beach Erosion

A woman with an umbrella walks along the shoreline in front of lifeguard towers at La Jolla Shores in San Diego, Dec. 2, 2014.
Associated Press
A woman with an umbrella walks along the shoreline in front of lifeguard towers at La Jolla Shores in San Diego, Dec. 2, 2014.

Study Predicts Significant Southern California Beach Erosion
Study Predicts Significant Southern California Beach Erosion GUEST:Sean Vitousik, lead author, "Disappearing Beaches: Modeling Shoreline Change in Southern California"

There are few things that define Southern California more than a coastline of Golden Beach is. That battled erosion with replenishment projects. They have a new tool for predicting future Russian in Southern California and monitoring exactly what rising sea levels are doing to our beaches. Joining me is Sean Matuszak with the University of Illinois and author of a new study disappearing beaches modeling change in Southern California. Thank you for having me. What does the model allow you to see or predict that you were not able to before. Before we could take a bunch of data that we could fit online to this data and we could sort of extrapolate but a lot of beaches in Southern California they have experienced accretion due to nourishment's from dredging harbors and placing sand on the shoreline. In a lot of cases in Southern California this would show accretion. We can account for the dynamics and other processes like sea level rise and we could show how beaches will respond to those processes and gives a better picture of how honorable we are. The so-called Cosmos model that you have come up with the USGS has come up with has some dire predictions about each erosion in Southern California. Tell us about those. Using our modeling system if we apply sealable projections between one meter and two meters which is a lot of sea level rise but as a potential future with wearing maybe on sea level rise with 2100 that we can show that a lot of the beaches in Southern California between 31 and 67% of the beaches in Southern California may be completely gone. That is eroded to the line of the infrastructure and beach by 2100. Which missions in San Diego could be most effective? The beaches in San Diego that are most affected are those that are supported Imperial beach and South Coronado and also La Jolla Shores also toured Black speech as you get further north admission date is affected a little bit the beaches that are not affected and is receiving March 1 is currently on Coronado Island. The beaches that are the most portable what makes them honorable? What makes them most portable is that there's a lot of development in those regions and it has already encroached on the shoreline. Many in San Diego already have problems right now. There are many beaches with seawalls that are already experiencing erosion problems. Those will be the ones that are the most vulnerable than the ones that are already experiencing some emotional problems near the sound of Imperial beach you have some prep -- examples of that. You report talks about the efforts that would be necessary. Is a seawall enough for what other kind of interventions are you referring to? Seawall is very effective defense against flooding? The problem with the seawall is if you have a chronically eroding shoreline or a shoreline that has been around the -- -- eroding for a long time you essentially do not have a sandy beach in front of the area anymore the problem with the houses. You can replenish the Senate is being eroded and you can have a nice -- you have both a sandy beach and some additional flood protection that seems to be a strategy going forward rather than building the walls because if we only built seawalls and -- we would not be a solution. It seems like it could be a problem. As the sea level gets higher we may be in a situation where the coast of California may look like New Orleans where we have beaches that sort of act as a loving with -- to prevent civil rights but if sea level rise gets two meters above present that we may have a situation where we are going to need to develop a lot of flood barriers in the area and where infrastructure may be actually below sea level. There are many coastal cities that have embarked on efforts. It is a rather expensive undertaking. Does it look to you like this should become may be a statewide effort in California. I think a lot of the beaches in California have already gotten a lot of each nourishment's like Los Angeles. Those beaches which have received large nourishment's do not seem as honorable as the areas where the teachers are very narrow. That is similar will nurse the beaches everywhere. While you are right that beach nourishment's are very expensive it would be interesting to see a cost-benefit analysis on the economics associated with a wide beach not only associated with tourism but also in flood protection by having the sandy beach you are actually saving money in the long run by preventing damaging floods from affecting the shoreline. So we could find out whether the cost benefits. I guess that is the next study. I've been speaking with Sean Vitousik lead author on a study of disappearing beaches.

More than half of Southern California's beaches could completely erode back to coastal infrastructure or sea cliffs by the year 2100 as the sea level rises, according to a study released Monday.

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Using a new computer model to predict shoreline effects caused by the rise of sea levels and changes in storm patterns from climate change,the research found that with limited human intervention, 31 percent to 67 percent of the beaches could vanish over the next eight decades with sea-level rises of 3.3 feet (1 meter) to 6.5 feet (2 meters).

According to the study, the beaches in San Diego County that will be impacted most are La Jolla Shores and Imperial Beach.

Human efforts will likely need to increase to preserve the beaches, study lead author Sean Vitousek said in a statement.

"Beaches are perhaps the most iconic feature of California, and the potential for losing this identity is real," he said. "The effect of California losing its beaches is not just a matter of affecting the tourism economy. Losing the protecting swath of beach sand between us and the pounding surf exposes critical infrastructure, businesses and homes to damage."

Vitousek was a post-doctoral fellow at the U.S. Geological Survey at the time of the study and is now a professor in the Department of Civil and Materials Engineering at the University of Illinois at Chicago.

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The study was published in the American Geophysical Union's Journal of Geophysical Research: Earth Surface.

The computer model looks at how sand is transported parallel and perpendicular to beaches as well as historical positions of shorelines and changes caused by waves and cycles such as the ocean warming phenomenon El Nino.

According to the researchers, its reliability was shown by accurately reproducing shoreline changes seen between 1995 and 2010.

Patrick Barnard, a USGS geologist and study co-author, said it shows that "massive and costly interventions" will be needed to save the beaches, which he described as both crucial to the Southern California economy and the first line of defense against coastal storm impacts.

Losing so many beaches would be unacceptable, said John Ainsworth, executive director of the California Coastal Commission.

"The beaches are our public parks and economic heart and soul of our coastal communities," he said.