Study: Expect fortifications in future against rising seas

During the next century, Charleston, Beaufort, Myrtle Beach and other populated, low-lying areas in South Carolina likely will install ambitious shore-protection devices to hold back rising seas, a new study shows.

But as this happens, vast areas of tidal wetlands will vanish, a situation that threatens wildlife and likely will violate federal clean water laws, the study found.

The sea is expected to rise between 8 and 23 inches during the next century, though some experts said if the polar ice caps continue to melt, the rise could be 3 feet or much more.

If left to nature, the coastline would naturally retreat inland. But millions of people along the American coastline now stand in the way of this process.

About 60 percent of the land roughly 3 feet above sea level along the East Coast has been developed and likely will be protected through dikes, bulkheads and other means, according to the study, published last week in Environmental Research Letters.

That percentage is even higher in Florida and the Northeast.

South Carolina's coastline is less developed, and this means state officials have a better chance to plan for the sea's rise and land's retreat by discouraging more development in floodplains and other low-lying areas, said the study's lead author, James Titus, a sea-level-rise expert at the U.S. Environmental Protection Agency.

Titus prepared the study independently from the EPA and said he was not speaking for the agency.

Unlike some sea-level studies, which identify areas likely to go under water, this study looks at which areas along the East Coast are likely to build dikes, seawalls, bulkheads and other protective devices.

The authors used data on wetlands and information from local planning agencies to create their maps. A key assumption in the study is that people who have properties vulnerable to rising seas will do something to keep these lands above water, Titus said.

The maps showed that many areas along the East Coast will end up like New Orleans, which has extensive shore protection devices to protect it from flooding.

"What's different is that many people make maps showing what's going to be underwater, but this report shows what people are going to do to hold back the sea."

The study shows that large areas far inland from Charleston's barrier island beaches are most likely to be protected from rising seas.

Of course, people may choose not to protect their land, Titus said, adding that the maps should help area leaders "decide where we really want to hold back the sea and where we don't."

Area leaders need to start thinking about sea level rise sooner rather than later, said Margaret Davidson, director of National Oceanic and Atmospheric Administration Coastal Services Center.

She said the study's timing is good because "there are profound infrastructure decisions that we need to be making, not just only in their siting but because of their designs."

A 3-foot rise in the sea level means that "we go from flooding at high tide in downtown happening four times a year to 200 times a year," she said. "This is happening, and it's not waiting for cap and trade."

Reach Tony Bartelme at 937-5554 or tbartelme@post andcourier.com.