Recent news articles proudly displayed measures taken in New York to prevent future damage from hurricanes and similar storms.
On Oct. 29, 2012, Hurricane Sandy, soon dubbed “Superstorm Sandy,” made landfall just north of Atlantic City, N.J. and caused widespread flooding and damage to homes. Now you can see new seawalls in place at beachfront property in Queens, intended to protect homes from raging seas.
But experience in coastal states farther south has shown that seawalls amount to a Band-aid, at best. A hurricane can measure 500 miles in diameter, and have a “fetch” (the area affected by winds and waves) of 1,000 miles. Pitted against this massive body of water are 5-foot tall walls of concrete, with houses immediately behind them. It’s not hard to figure out who is going to win the battle.
States like North Carolina, South Carolina and Virginia, which see their barrier islands and sandy beaches visited by tropical and winter storms on a regular basis, have long had laws in place that prohibit placement of hard structures. Not only do they fail in the most severe storms, but they also cause beach erosion.
Instead of allowing sand to spread over a large beach area, a seawall concentrates the wave force along a rigid line. Sand gets washed away in front of it, and soon there’s nothing but a stone wall and a steep, highly eroded beach that’s only accessible at low tide. Where sand is washed out from under it, a seawall likely will collapse and fail.
In Georgia, the 1992 Shore Protection Act allows seawalls if they aren’t vertical. On the Gulf Coast, a giant seawall was just finished in Bay St. Louis, Miss., lining 1.5 miles of beachfront.
The purpose of such hard structures isn’t to protect the natural beach environment for visitors. It is to preserve property behind the high-tide water line. As a result, more and more natural beachfront is lost to development as the sand washes away and has to be replaced by material dredged up elsewhere.
Such beach “renourishment,” carried out by the Army Corps of Engineers, has become common practice on barrier islands where development has caused the breakdown of natural sand movement. A much better approach to beach management would be to consider beachfront property as temporary and expendable. Entombing entire communities in cement is a bet we sooner or later stand to lose.
Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His email is firstname.lastname@example.org.