Holding the line on terminal groins

Advocates for Inlet Solutions, an organization of Figure Eight Island property owners lobbying to change state law and build a terminal groin to protect several houses from erosion, believe such a structure will not only protect the beach but also that it will do so without environmental impacts.

While the Advocates organization certainly has the money, influence and political connections to get what it wants, one key element is missing: proof that a terminal groin will work. Because there isn't any. The proposed terminal groin at the exclusive island near Wilmington will create serious erosion problems.

But that hasn't stopped the group from listing a number of so-called terminal groin research studies on inletsolutions.org, the group's Web site. It is not a surprise to us that theses studies have nothing to do with terminal groins. There are no studies showing that such structures don't do damage to adjacent beaches.

A terminal groin is a long wall, usually made of rock or steel, that extends seaward, perpendicular to the shoreline, adjacent to an inlet.

A number of the articles listed are in the Journal of Coastal Research, Special Issue 33 (2004), which carries the subtitle "The Interaction of Groins and the Beach." Thumbing through this volume, one can get a quick lesson not on terminal groins but in the huge amount of damage done to beaches by groins and other shore-perpendicular structures.

One study in their list makes no mention of groins. Another is concerned with offshore breakwaters. Two are concerned with lakes and structures that have nothing to do with the question at hand.

Most are about short groins away from inlets. One paper is by the late Per Bruun, recognized as the father of coastal engineering, who in times past repeatedly said groins are a losing proposition. Several of the papers are concerned with rocky shorelines, which have little bearing on barrier island shorelines. The only paper (by Robert Dean) about terminal structures adjacent to inlets never even mentions terminal groins.

In another dubious effort to hype terminal groins, the Web site quotes coastal engineer Dean as saying that terminal structures should be an option to manage inlets. He even goes so far as to call the terminal groin at Oregon Inlet a success.

But terminal groins disrupt the flow of sand. And when the flow of sand is disrupted, problems ensue.

The terminal groin built in 1992 at Oregon Inlet to protect the Bonner Bridge, for example, has required a total of 8 million cubic yards of sand to combat downdrift beach erosion along the Pea Island National Wildlife Refuge. The erosion rate continues at a pace faster than before this erosion control structure was built.

The Web site also quotes one of us (Orrin Pilkey). Although Pilkey wasn't speaking of terminal groins, the quotes are genuine -- there are some examples where groins have lengthened the life-span of nourished beaches. The site neglects to mention, however, that as the beach retreats landward beyond the tip of the groin, the sand supply of adjacent beaches is reduced and downdrift erosion ensues.

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TERMINAL GROINS ARE CLEARLY NOT A SOLUTION to the state's coastal development problems. The depth of understanding is so pervasive and evidence so overwhelming that a recent statement signed by 43 coastal experts (not everyone is a geologist) even concluded that any further study of groins is pointless.

Even so, pressure from coastal property owners desperate to protect their investments and communities interested in preserving tax revenue will continue.

North Carolina has held the line on its coastal erosion control structure policy for decades, and allowing even a "pilot project" will make it virtually impossible to continue to do so, as more and more buildings get closer and closer to the eroding shoreline.

So now we wait. We wait to see whether elected officials in Raleigh have the political courage to do what's best for all North Carolinians. Certainly they need pay little attention to Advocates for Inlet Solutions. The future of our coast is on the line.

(Orrin H. Pilkey is James B. Duke professor emeritus at Duke University's Nicholas School of the Environment. Andrew S. Coburn is associate director of the Program for the Study of Developed Shorelines at Western Carolina University.)