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 [emphasis mine].And there's also this gem, from this 2008 post to the Progressive Pulse:
Promoters argue that the terminal groin will not create problems, which is not true. The very phrase “terminal groin” is a lie of Baron Munchausen proportions! It was a term first used incorrectly at Oregon Inlet to avoid the inflammatory word "jetty" after a long nationally- prominent societal battle over jetty construction. After 25 years' worth of evidence had accumulated indicating that building a jetty at Oregon Inlet wouldn’t work, the state said, “We're not building a jetty – we're building a terminal groin.” And just as predicted, the 3000-foot Oregon Inlet jetty has created immense and very costly erosion problems.
The aquarium's hurricane flood tower should be kept in mind as you drive down the exit road and see the tall (and to my eye, incredibly ugly) sand barricade bulldozed to protect the bathhouse parking lot and US 421 south of Fort Fisher State Park. This sand pile was made necessary by beach retreat on the south side of a beach-hardening project designed to protect Fort Fisher's seaward ramparts from shorefront erosion...if you want to see what happens to beaches downstream of erosion control structures, park at the bathhouse and walk out on the beach to the north. There you will see the stone erosion control structure with the beach about 200 to 500 feet back from its prestructure location. Publicly owned beach and dune have been eroded away, perhaps in a justifiable trade for protected ramparts, but only time will tell the full environmental cost of the deal.
Image courtesy of Len Pietrafesa: Groins built at right angles to the shore at Cape May, New Jersey, ostensibly to slow the migration of sand. The groins interrupt the flow of longshore currents, so sand is trapped on their upcurrent sides. This view is toward the south, and south of the groins, on the downcurrent sides. The effect of the groins is that sand is eroded away from the beaches.The natural beauty and economic value of North Carolina’s public beaches and inlets exists today in large measure because our state leaders long ago adopted a conservative management policy that bans the use of hardened structures—seawalls, jetties and groins of any kind—from our coast.
In 1979, erosion control structures first became regulated in NC; the initial regulations prohibited hardened structures for new developments, but those already in place could remain. But the ban changed in 1985. From that point on, all permanent erosion control devices were prohibited. Even the old ones had to go.North Carolina’s beaches face a lot of problems, including overdevelopment, rising sea level, rapid erosion rates, and a paucity of beach-compatible sand for beach replenishment...There is unanimous agreement among N.C. coastal geologists that mining of inlets, and groin or jetty emplacement, will likely create more problems than they solve. But our message is viewed by developers and politicians as negative, one that stands in the way of progress.
