Photograph courtesy of ExploreGeorgia.org
With one-third of the salt marshes on the U.S. Eastern Seaboard, the Georgia coast is celebrated for its natural beauty—but natural can be a deceptive concept. Humans are part of nature; to effects good and ill, we’ve shaped the world around ourselves. That includes the coast.
“When the first settlers came to the U.S., there were not huge salt marshes,” says Herbert Windom, a professor emeritus at the University of Georgia’s Skidaway Institute of Oceanography. Arriving in Georgia, European colonists converted vast amounts of forestland to agriculture, thereby loosening the soil, which made its way into the rivers flowing seaward—the Savannah, the Altamaha, and others—and thus to the coast, where it collided with another powerful phenomenon: Georgia’s tides, the highest on the East Coast. The countervailing force of the tides caused some of the sediment to settle at the mouths of the river deltas, expanding the marshes to what they are now. The salt marsh results from the meeting of river and tide.
But that balance may be coming undone—the effect, Windom and coauthor Jonathan Palmer find in a new paper in the Journal of Coastal Research, of yet more human activity. In the 20th century, government projects promoting flood control and hydroelectric power led to the damming of many rivers, which blocked the downstream flow of sediment. And more recently, as the globe warms, the oceans are rising, to the tune of about one foot per century. (A rate that, unless carbon emissions slow dramatically—and soon—will continue to increase.) Those two facts combined mean “sediment delivery is not keeping up with sea level rise,” Windom says. “We already see evidence of their being eroded—we’re losing marsh.”
Windom and Palmer focus their research on the Georgia Bight—the inward curve of coast between the Carolinas and Florida. But they point out that these sorts of environmental concerns are never strictly local: Elsewhere, local interventions in two major southeastern river basins have led to a three-decades-and-counting water war between Georgia, Florida, and Alabama. “We think, ‘This is the way nature should be always,’” Windom says. “And it’s not. It’s always changing. We’re causing some of those changes—we’re part of nature.” And we will, in turn, have to grapple with the changes we’ve caused.
This article appears in our April 2023 issue.
