Friday, August 27, 2010

After Katrina, Gulf Coast still vulnerable

Jessica Marshall in Discovery News: In the five years since Hurricane Katrina slammed the U.S. Gulf Coast, breaching levees and flooding New Orleans, one thing hasn't changed: Louisiana is still sinking at a rate that's only going to quicken. The questions now are, is New Orleans ready for another storm like Katrina? And going forward, what's to be done about a region that's headed back into the sea?

Since the storm, the U.S. Army Corps of Engineers and others have spent millions to rebuild the city and its flood protection system. "We'll be absolutely ready for it," said Corps communications officer Wade Habshey, who is based in New Orleans. "What we have in place now can withstand a Katrina-level storm."

Beyond the city, though, there are still concerns. As coastal areas erode, residents living near the shore face a greater threat of flooding. This could become worse with global warming. Colonel Edward Fleming, commander for the New Orleans district of the Army Corps of Engineers, says coastal restoration projects are underway, and that he's in Washington seeking approval for six more this week. Still, he concedes that the state is losing 27 square miles of land a year.

…Leonard Bahr, a coastal scientist formerly with the Louisiana governor's office, now maintains an independent blog about the Louisiana coast ( "The model of bolstering the protections in New Orleans is inappropriate to be used across the rest of Louisiana," he said. "Once you build levees and start pumping, the rest is history. You're doomed to perpetual pumping."

…While New Orleans may be in better shape to face a storm, a bigger issue outside the city is the loss of wetlands. Wetlands provide a buffer against storms, and offer crucial habitat for Gulf fisheries species. Coastal wetlands are constantly eroded, especially in big events like Katrina. Historically, the erosion was balanced by the deposit of new sediment downriver.

…Sediment loss is only part of the problem facing delta lands, the Nature Geoscience study noted. Even if all of the river's sediment could proceed freely to the delta, sea level rise is outpacing sediment deposition by more than threefold, meaning delta lands are certain to disappear.

Crack in 17th Street Canal floodwall near Metarie Pumping Station. Shot by Infrogmation, who has taken so many informative, moving pictures of Katrina's aftermath. Wikimedia Commons, under the Creative Commons Attribution 2.5 Generic license

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