Why are beaches and coastlines eroding and what can be done about it?
—Jesus Lopez, Santa Maria, CA
Beach erosion has both human and natural causes. The process of erosion carries beaches out to sea, but it also created them over millions of years from the rock-strewn shores that originally covered our planet. “Without erosion, we would not have the beaches, dunes and highly productive bays and estuaries that owe their very existence to the presence of barrier beaches,” says Jim O”Donnell, a coastal processes specialist with the Sea Grant program at Woods Hole Oceanographic Institution.
Sand moves naturally through the actions of wind and the tide, but it is helped along by human actions, and the beach erosion problem is growing dramatically. The main causes are overbuilding right to the water’s edge (a practice protected by federal flood insurance), rapid rises in sea level exacerbated by global warming, a gradual sinking of coastal land, and inept attempts to fix the problem.
Scott L. Douglass, author of Saving America’s Beaches and a professor at the University of South Alabama, worked his way through college lifeguarding on the New Jersey shore. Like many beach experts, he’s a major critic of the erosion-promoting effects of jetties, seawalls and dredging. Human activity has removed “more than a billion cubic yards of sand from the beaches of America, enough to fill a football field over 100 miles high,” he points out. Douglass prefers beach replenishment, which he says “adds sand to the system,” but he acknowledges that, with sea levels rising at a rate of six inches every 100 years, beaches may not be able to keep up.
Rising sea level means that wetlands and other low-lying lands get inundated, beaches erode, flooding intensifies, and the salinity of rivers, bays and groundwater tables increases. Sea level is rising more rapidly along the U.S. coast than worldwide, according the U.S. Environmental Protection Agency (EPA). In the next century, a two-foot rise is likely, but a four-foot rise is possible; and sea level will probably continue to rise for several centuries, even if global temperatures were to stop rising.
Orrin Pilkey, who directs the Program for the Study of Developed Shorelines at Duke University, believes that in many cases it would actually be cheaper to move buildings back from the water’s edge than to fund 10 to 20 years of constant beach replenishment, but his ideas have not had many takers among shoreline communities. Some states and localities in the U.S. and around the world have “set back requirements,” restricting development on the shoreline. Protecting and restoring natural barriers to erosion, like dunes, wetlands and vegetation close to shore are also natural, low-cost ways to fight erosion.
CONTACTS: Woods Hole Oceanographic Institution, (508) 289-2252, www.whoi.edu; EPA Coastal Watershed Factsheets, http://www.epa.gov/owow/oceans/factsheets; Duke University Program for the Study of Developed Shorelines, (919) 684-2206, http://www.env.duke.edu/psds.