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Tuesday, February 21, 2006 | Over any given year, surfers see sand leave with winter’s storms and return with summer’s calm – a cyclical rhythm as comforting as the tides or seasons. It makes our favorite surf spot have perfect sandbars in winter and lousy ones in the summer.
However, it has been proposed by many, that in San Diego this sand cycle has become a backwards dance. That each year the same amount of sand waltzes off with the waves and fewer new granules come to replace those lost to the sea.
According to data cited in a new book, “Living with the Changing California Coast,” by Professor Gary Griggs of the University of California Santa Cruz and Reinhard Flick, an Oceanographer with the California Department of Boating and Waterways, who wrote the San Diego chapter of the book, exactly such a process should be occurring.
Less than 50 percent of the sand that used to be discharged onto San Diego’s beaches by rivers each year now arrives, due to the construction of dams and urbanization of watersheds. Additionally, in areas such as Oceanside, up to 18 percent of the sand, which used to be supplied by local bluffs, is now cut off by seawalls.
Since rivers and cliff or bluff erosion are the only two natural sources of sand for Southern California beaches, and waves take approximately the same amount of sand off a beach each year, one would expect erosion on a massive scale, with almost all beaches missing at least fifty percent of their natural sand and others approaching 70 percent. However, according to Griggs and Flick, and from my own personal observations of San Diego’s Beaches over nine years as a daily surfer here, this scenario has not yet occurred.
According to Flick, a major reason why so much natural sand has been trapped is human activity, specifically dredging to build harbors and drain lagoons.
“Southern California dams have basically cut sand supply in half, but much of that has been made up from artificial human nourishment…so beaches have not disappeared,” Flick said. “The nourishments in San Diego have come from the dredging of San Diego Bay, Oceanside harbor, Silver Strand and Batiquitos Lagoon.”
As a surfer, who has over the last several days been discussing this topic quite frequently with my peers, I have reached a slightly ironic conclusion about the situation. I’m part of the reason the problem is going to be hard to solve. I mean, while so many dams and urbanized watersheds choking off natural sand flow could create a tragedy for the coast, I also shower every day and have automatic sprinklers in the lush garden surrounding my house. San Diego is a desert.
I don’t even have the showerheads that save water.
So, un-damning the waterways and de-urbanizing the watersheds doesn’t seem very practical, especially in a state that has experienced a 70-percent population increase in the last 40 years, and in which 75 percent of the population lives on the coast.
However, a problem may arise with continuing to do nothing, because, as Flick noted in a phone interview, there are currently no more harbors or other large scale dredging projects planned in San Diego or Southern California, and maintenance dredging of harbors does not add sand to beaches.
So, will we now see collapsing cliff sides, vanishing beaches and uncountable damage to coastal property and infrastructure; the result of a century during which the state’s rivers had 400 dams placed to impede their flow?
One solution, which was tried unsuccessfully by the San Diego Association of Governments, or SANDAG, several years ago, was to place 2,000,000 cubic yards of sand, dredged from offshore, onto 12 area beaches. The project cost a reported $17.5 million dollars, Griggs said, and most of the sand was gone in two years with some not making it through one winter.
To Griggs it means that California’s beaches have too much wave action for sand to survive without dredging.
Flick, while disappointed by the result, said that if larger quantities of sand had been placed in fewer areas, instead of the smaller quantities that were placed on 12 beaches, the experiment might have succeeded.
“Some people say that the project didn’t work,” said Flick “But that is not really true, because it was also to see if all the local beach cities could cooperate, which is very hard with nine cities, but everything functioned smoothly, so it will be of great good for future projects and could be very important.”
I hope so, because I have a feeling that unless San Diego’s local coastal governments can figure out a way to keep up beach nourishment, without building endless harbors, many of my favorite surf spots might not be around for the next generation of wave riders.
“The system of making up the sand deficit by building small craft harbors worked for 50 years,” Flick said. “But it was and still is a temporary solution.”
And worse yet, Griggs said that we are currently in a scientifically proven 18,000-year period of global warming with sea levels rising in San Diego eight inches over the last 93 years.
The questions, then, are how much sand will San Diego’s beaches lose without any new major dredging projects, or a better solution to sand nourishment by coastal cities; and how much higher will the sea level rise in the coming years? If the answers turn out to be, a lot, to both queries, investors in beachfront homes might want to start looking in the La Jolla Hills for future prospects.
edwardgraham1@earthlink.net