The biggest U.S. worry during the unprecedented storm sequence in the Gulf of Mexico was about the cities of New Orleans and Morgan City, Louisiana. Their low elevations and copious water supply from the Mississippi and Atchafalaya River make those towns extremely vulnerable to flooding. Luckily, the Mississippi wasn’t at a dangerous high water stage this fall. If the Morganza Spillway had to be opened to relieve that river, the water draining into the Atchafalaya might have made evacuations necessary in Morgan City for every storm.
This sends a signal to the East Coast. A future year with a similar number of storms, traveling along the eastern coastline instead of the Gulf, will bring trouble to Georgia and the Carolinas. Instead of a giant river delta like the one in the Gulf, our shores are lined by barrier islands. They are sand dunes left over from the most recent Ice Age, piled up by wind about 18,000 years ago. When the climate warmed, ocean levels rose again. The dunes became submerged and formed islands. Now, with towns and subdivisions on them, coastal erosion is a constant problem.
Different than the horrendous onslaught brought by hurricane waves, even winter storms chew away at the coastline through constant wave action. Sand removed from the beaches ends up deposited elsewhere, which often results in shifting property lines. It’s important to know that barrier islands aren’t straight. They usually have something of a hot-dog shape. The sand migrating along the shore shortens an island on one end and lengthens it on the other. While that’s happening, it appears that the beach is currently building up and becoming wider on the losing end. This can mislead property owners and buyers into thinking that the houses in that area are safe. But a widening beach often means that the inlet, separating the island from the next one, is coming for it and the widening is just temporary.
I have observed the process at the North Carolina barrier islands numerous times. The migration of the shoreline at places like Carolina Beach, Wrightsville Beach, Figure Eight Island and Topsail Beach can be as rapid as 30 feet per month. Housing on barrier islands at the U.S. East Coast is best regarded as temporary. Another upswing in the frequency of coastal storms is likely to change the map significantly.
Rudi Kiefer, Ph.D., is a professor at Brenau University, teaching physical and health sciences on Brenau’s Georgia campuses and in China. His column appears Sundays and at gainesvilletimes.com.