FOLLY BEACH — If the Charleston jetties were removed, nobody really knows what difference it would make with the erosion plaguing this city.

More than 1 million tons of stone were used to construct the jetties, two lines of rock walls stretching three miles from the mouth of Charleston Harbor to protect the shipping channel.

The jetties are said to have disrupted sand flow in the current along shore, robbing Morris Island and Folly Beach of sand needed to keep beaches from eroding.

Estimates of the jetties’ influence on Folly’s beach erosion have ranged from about one-third to well more than half. But coastal scientists readily concede it’s hard to gauge.

If the jetties were not there, Folly would be another barrier island in the wash of longshore current sand, with its spits being cut and carved by inlet sand shoals as they move ashore.

“I don’t think there would be erosion like (now),” said Miles Hayes of Research Planning.

But Tim Kana, of Coastal Science and Engineering, said Folly would be as erosive at its inlet spits as Isle of Palms at Breach and Dewees inlets — where recent erosion trends also have threatened property — because of the effects of sand shoaling.

“It is disingenuous to blame all of Folly Beach’s erosion on the jetties,” he said.

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