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December 2, 1996 E-mail: geotimes@agiweb.org

Coastal Zones: Natural Change, Man-made Conflict

ALEXANDRIA, VA. -- The rhythm of the sea, a slow sinking sunset, the briny air -- these are only a few of the charms of living near the ocean. But the tranquil facade of coastal zones is complicated by a continual process of erosion and buildup. The ever- changing boundary between land and sea ignores the domain of property and economics. In this month's Geotimes, coastal managers and scientists discuss the struggle to balance the interests of society with the unalterable processes of coastal systems. In his article, "Conflict on the Not-So-Fragile Barrier Islands," Stanley R. Riggs, professor at East Carolina University, explains what happens when real-estate developers ignore the dynamics of coastal systems. "Barrier island systems are extremely d ynamic, energy-absorbing sponges that change continuously through time in response to changing energy inputs," says Riggs. "Immobile houses, with their absolute deeds, are very much out of equilibrium with even the smallest changes in this dynamic and mob ile barrier island system."
On the Isle of Palms, S.C., the invading inlet is reclaiming the beach, taking with it a cluster of high-priced houses -- despite the U.S. Supreme Court's ruling in favor of the land owner who sued the state when coastal regulations set limits on b arrier island development. "The natural coastal system will ultimately be the judge, the verdict will be rendered with the passage of time, and society will be the victim," concludes Riggs.
Erosion and property damage are even more widespread on the islands of Hawaii, home to the most expensive real estate in the nation. "Much of Hawaii's coastline is naturally receding because of the rising sea," state authors Melanie Coyne, Roger Mul lane, Charles Fletcher (University of Hawaii), and Bruce Richmond (U.S. Geological Survey) in their article, "Losing Oahu: Erosion on the Hawaiian Coast." As the sea rises, the beach migrates inland at a constant width fed by sand liberated by erosion. Se awalls and revetments (revetments), built to armor the coastline and protect beachfront property, have actually caused further degradation by robbing the migrating beach of its sustenance -- sand. "Any reduction in the width of the beach is a cause for co ncern on the crowded Hawaiian coastline because less beach means more coastal flooding when high waves and tsunamis occur," say the authors.
In their article, "Surf as Coastal Resource: The Wave of the Future," Chad Nelsen and Peter Howd describe the unique agreement that Chevron and coastal managers made to protect the surf -- an oftentimes overlooked coastal resource. Chevron agreed t o construct an artificial reef in Santa Monica Bay to counter the effects of their groin project, which had "over-steepened" the beach. "As waves approach the shoreline and shoal, they can dramatically transform in several ways," explain Nelsen and Howd. "Refraction and diffraction occur as the waves interact with the ocean floor, slowing them and changing their direction." Designing the new reef illustrated how physical science can help land managers resolve societal issues.

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