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Katrina: Sea change on the Gulf Coast – Part 3 • Environment

By Peter N. SpottsStaff writer of The Christian Science Monitor / August 31, 2006



PECAN ISLAND, LA.

From inside a small motor boat, this glimpse into the future of southern Louisiana's hurricane protection isn't much to look at.

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It's an embankment, rising a mere foot and a half above open marsh water here in the Rockefeller State Wildlife Refuge. Cordgrass, just starting to flower, sprouts along its edges like hair on a monk's tonsure.

"We planted those in the early part of this year," says Darryl Clark, with the US Fish and Wildlife Service (FWS), who eases in an aluminum outboard for a closer look. "They're doing very nicely."

The 1,000-foot-long barrier, one of several that form a sergeant's-stripe pattern in the open water, are a small part of a vast effort to rebuild the region's natural hurricane defenses, restore the ecological vitality of its wetlands, and perhaps slow the alarming rate at which the region is sinking.

The coast's watery descent may be a key early test of how other coastal communities around the world might deal with rising oceans and stronger tropical cyclones. Many scientists say these are likely results of global warming.

At best, southern Louisiana would become a model for how to build sustainable and resilient seawater defenses that help keep coastal populations where they are, some specialists say. At worst, they add, the region's enhanced defenses could buy time – perhaps a century or two at most – for residents to figure out whether they need to pull up stakes and head north to higher, drier ground.

"We have so much of this state at or below sea level. You have high rates of subsidence. You get concentrated populations, such as New Orleans and other coastal cities. You have a high incidence of high-magnitude events – hurricanes and winter storms ... it's like putting the whole system on fast forward" compared with other delta regions, says Gregory Stone, a professor in the department of oceanography and coastal sciences at Louisiana State University in Baton Rouge. "A lot of engineers and scientists are looking to see how we're going to come out of this ordeal."

Experts are not at a loss for ideas. For example, in July, the US Army Crops of Engineers served up the outline of an ambitious, long-term plan to cut the risk from Category 5 hurricanes in a report to Congress. Rather than relying principally on levees that hug urban areas, the Corps is considering a triple-layer defense.

Extensively restored barrier islands would be the first line of defense, absorbing the first shock from the surge of high water that hurricanes bring. Revitalized wetlands would form the second line of defense. Armored levees and other forms of barriers stretching from Texas to Mississippi would form a final defense, a Maginot line often a few miles inland. These final barriers would be designed to allow boat traffic to move back and forth. By some accounts, those levees could reach 30 to 60 feet high.

Such an engineering project would take years and tens of billions of dollars to complete. In the near term, improving the region's natural hurricane defenses would fall to those who are trying to restore its wetlands and barrier islands. They also hope to stem the sinking – or subsidence – that is allowing the Gulf of Mexico to creep farther northward.

The region, is "ground zero for three ecosystems in a state of collapse," explains Russell Watson, who like Mr. Clark, is with the FWS office in Lafayette, La.

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