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What Causes Beach Erosion?

Is beach erosion a natural cycle or is it getting worse with rising sea levels?
beach erosion



Dr. David Lindbo, courtesy Flickr.

Dear EarthTalk: I’ve noticed a lot of beach erosion along the eastern U.S. coast. Beaches are virtually nonexistent in places. Is this a usual cycle that will self-correct, or are these beaches permanently gone from sea level rise or other environmental causes?
-- Jan Jesse, Morristown, TN

Unfortunately for beach lovers and owners of high-priced beach-front homes, coastal erosion in any form is usually a one-way trip. Man-made techniques such as beach nourishment—whereby sand is dredged from off-shore sources and deposited along otherwise vanishing beaches—may slow the process, but nothing short of global cooling or some other major geomorphic change will stop it altogether.

According to Stephen Leatherman (“Dr. Beach”) of the National Healthy Beaches Campaign, beach erosion is defined by the actual removal of sand from a beach to deeper water offshore or alongshore into inlets, tidal shoals and bays. Such erosion can result from any number of factors, including the simple inundation of the land by rising sea levels resulting from the melting of the polar ice caps.

Leatherman cites U.S. Environmental Protection Agency estimates that between 80 and 90 percent of the sandy beaches along America’s coastlines have been eroding for decades. In many of these cases, individual beaches may be losing only a few inches per year, but in some cases the problem is much worse. The outer coast of Louisiana, which Leatherman refers to as “the erosion ‘hot spot’ of the U.S.,” is losing some 50 feet of beach every year.

Of particular concern is the effect climate change, which not only causes sea levels to rise but also increases the severity and possibly the frequency of harsh storms, has on beach erosion. “While sea level rise sets the conditions for landward displacement of the shore, coastal storms supply the energy to do the ‘geologic work’ by moving the sand off and along the beach,” writes Leatherman on his DrBeach.org website. “Therefore, beaches are greatly influenced by the frequency and magnitude of storms along a particular shoreline.”

Besides collectively lowering our greenhouse gas emissions substantially, there is little that individuals—let alone coastal landowners—can do to stop beach erosion. Building a bulkhead or seawall along one or a few coastal properties may protect homes from damaging storm waves for a few years, but could end up doing more harm than good. “Bulkheads and seawalls may accelerate beach erosion by reflecting wave energy off the facing wall, impacting adjacent property owners as well,” writes Leatherman, adding that such structures along retreating shorelines eventually cause diminished beach width and even loss.

Other larger scale techniques like beach nourishment may have better track records, at least in terms of slowing or delaying beach erosion, but are expensive enough as to warrant massive taxpayer expenditures. In the early 1980s, the city of Miami spent some $65 million adding sand to a 10-mile stretch of fast-eroding shoreline. Not only did the effort stave off erosion, it helped revitalize the tony South Beach neighborhood and rescue hotels, restaurants and shops there that cater to the rich and famous.

CONTACTS: Stephen Leatherman, www.drbeach.org; National Healthy Beaches Campaign, www.ihrc.fiu.edu/nhbc.

EarthTalk is produced by E/The Environmental Magazine. GOT AN ENVIRONMENTAL QUESTION? Send it to: EarthTalk, c/o E/The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; submit it at: www.emagazine.com/earthtalk/thisweek/, or e-mail: earthtalk@emagazine.com. Read past columns at: www.emagazine.com/earthtalk/archives.php.

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