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BREAKWATER BREAKDOWN: Hard Water

Published on 9/19/2007 on the District Weekly

With sea levels rising worldwide attributed to global warming, aren’t we approaching a day when all waterfront cities will need the protection of a breakwater? Doesn’t the Long Beach Breakwater—the massive wall of boulders that sits 1.5 miles off our shore—give this city a head start?

Nope. Breakwaters do not prevent tides, cannot restrain tsunami and will not completely protect oceanfront property from storm damage, according to Tom Garrison of Orange Coast College, author of a widely used series of college textbooks in oceanography.

Garrison says breakwaters are only designed to mitigate wave strength; when open-ocean waves strike the outside of the breakwater, only a fraction of their original force continues toward shore.

Contrary to self-serving rumor, the Long Beach Breakwater was not built to protect Belmont Shore and the Alamitos Peninsula. It was built to protect the U.S. Pacific Fleet in the 1930s and 1940s, not from waves but from submarine attack. It was built in a hurry and with little regard for the natural environment and has caused a great deal of unanticipated erosion and circulation problems within San Pedro Bay.

So what to do about the rising tides, which the Environmental Protection Agency projects will surge between two and seven feet in the next 200 years?

The EPA and coastal engineers recommend “soft” approaches, such as beach nourishment (pumping sand onto the beach) and artificial dune construction (more sand pumping, just in the shape of dunes). These create the best protection against the unpredictable ocean: a very wide beach. Another method, called “living shorelines,” involves planting erosion-combating grasses and succulents, which also provide habitat for wetland creatures.

“Hard” construction tactics like breakwaters and jetties are expensive and tend to dramatically alter nature. That said, there is one theory that suggests a way the Long Beach Breakwater might offer some protection from rising tides—doubling its current height.

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