Tuesday, November 15, 2005

About the levees

There are several meaty articles about levees and flood protection in New Orleans today.

The Times Picayune continues their excellent series on the Dutch flod prevention measures, this time discussing the unforeseen bad effects of their levee and dam system.
The Dutch experience is a cautionary tale for south Louisiana, where engineers may have to intrude upon the delicate marshlands surrounding New Orleans as never before, building new floodgates and levees to protect the region against a Category 5 hurricane.

Hurricane protection and marsh restoration projects will have to be knitted together into a single system with divergent goals. Storm surge protection requires walls of one kind or another. But estuaries and marshes are living systems. Wall them off and they may die. Putting holes in the walls can help by letting water flow in and out. But no one really knows yet how – or if – these ambitious aims can be balanced.

In another article The Times Picayune also indicates that Dutch thinking is beginning to have its influence in Washington. Senators are beginning to acknowledge that just building higher levees is not the answer.
"You can't build levees high enough around (New Orleans). You have to go out," Vitter said.

He said the corps engineers described a "very conceptual" vision of an outer flood protection system without specifying whether it would comprise levees, dams, gates or a combination of those structures. "The basic idea is to have an outer level of protection further out from the city, particularly to the south and east," he said.

The Louisiana senators are pushing for Congress to approve by the end of the year financing for the corps to study and design such a system, Vitter said.

The New York Times recapitulates what Louisiana residents have long known: the marsh, vital for fisheries and for storm protection, is disappearing.
He said some marshy areas east of the Mississippi River lost 25 percent of their land areas in Hurricane Katrina, which came ashore more than 100 miles east of New Orleans. A strong hurricane that approached New Orleans from the south, along the path of the river, would do even more damage, he said.
(Hey, it's easy. Give us back our Mississippi mud.)

But in the same paper, we can find this bit of wisdom:
But would healthy marshes have saved New Orleans from the devastation of Katrina?

"Not a chance,"
said Joseph Kelley, a coastal scientist at the University of Maine who was a member of an expert panel convened by the National Academy of Sciences to study Louisiana's plans for marsh restoration.

In the first place, the floodwater that caused the most damage in New Orleans entered the city not from the marshes but from Lake Pontchartrain and, possibly, the Mississippi Gulf Outlet, a much-reviled canal that runs from the river at New Orleans southeast to the gulf.
Well, true enough, but still, we need to restore the marshes.

Finally, this cold bucket of water comes from the coordinator for Gulf Coast recovery.

Donald Powell said he may not be able to quantify how long-term recovery efforts are progressing for at least eight months in the devastated region that he compared to a war zone. But he said he and local authorities need to focus first on security – making sure that levees can withstand another huge storm.

"I think New Orleans and Louisiana need to be safe," Powell said in an interview with The Associated Press.

However, "I'm not sure what the science dictates," Powell said when asked if the levees would be rebuilt to withstand a Category 5 hurricane, as Gulf Coast officials have requested. "Clearly, I think they're going to be rebuilt up to a Level 3 but ... they were not a Level 3 when the storm came. And then study and understand what the science is to get to a Level 5."

"But the levees clearly are important," he said

What did this guy run before he got this position? Oh, yeah, head of FDIC and friend of the president. "But the levees are clearly important" -- I'm glad he has his priorities straight, if a bit understated. How about "clearly vital" or "goddamned clearly absolutely important to New Orleans' survival"?

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