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New Orleans levee-risk study faulted

Engineers criticize holes in the analysis, which could affect waterways from Florida to the Sacramento Delta.

December 31, 2006|Ralph Vartabedian | Times Staff Writer

When the Army Corps of Engineers admitted in June that design flaws in the New Orleans levee system had caused most of the flooding during Hurricane Katrina, it seemingly left little to argue about.

But the fight wasn't over. The Corps is now engaged in an effort to predict how New Orleans would fare in the next big hurricane, and is once again being second-guessed by some of the nation's top civil engineers.

The National Research Council complains that the Corps' official investigation into the levee failures reaches premature conclusions, glosses over problems, and fails in its most important task: giving the public the information it needs to make informed decisions about living in New Orleans.

The Corps' analysis will play a major role in determining the city's future -- including whether more than 200,000 former residents could rebuild abandoned neighborhoods and whether insurers can provide coverage at an affordable rate.

For The Record
Los Angeles Times Sunday January 07, 2007 Home Edition Main News Part A Page 2 National Desk 1 inches; 34 words Type of Material: Correction
Levee-risk study: A Dec. 31 Section A article about engineers' criticism of a federal New Orleans analysis misspelled the name of Les Harder, levee chief at the California Department of Water Resources, as Harter.

The stakes are high, not only for the integrity of the levees around New Orleans but for similar levees that protect millions of Americans who live along vulnerable coastlines and rivers across the nation. Many were built on the same mucky foundations and with the same flawed engineering assumptions as the notorious failed 17th Street levee in New Orleans.

The suspect levees stretch from Florida's Lake Okeechobee to the rivers of California's Central Valley and the Sacramento-San Joaquin Delta, which has 2,300 miles of levees that protect cities and farmland.

The Corps' investigation is essential to understanding California's situation, said Les Harter, the levee chief at the California Department of Water Resources.

"The floodwalls in New Orleans were 15 years old, and they failed," Harter said. "Our levees are 100 years old. We estimate we have one-half the level of protection that New Orleans had."

The Corps is about six months behind schedule in issuing an all-important "risk analysis," a massive body of work that is intended to tell the public how likely New Orleans is to flood again from a big hurricane.

The analysis is supposed to explain in precise detail how well specific sections of the city are protected against hurricanes, using evidence that hurricanes have intensified in recent years. The analysis would produce detailed maps.

Though the risk analysis has not been completed, the Corps did lay out the methodology it planned to use. Since then, the Corps' work has been scrutinized by two key groups, the National Research Council and the American Society of Civil Engineers.

Its methodology has prompted much of the criticism, along with the Corps' failure to say how confident it is in its assessment or to put the future risk in a historical context that New Orleans residents can understand, according to Richard Luettich, a member of the NRC review team and a professor at the University of North Carolina.

The research council, a quasi-federal organization that brings together the nation's top experts on various public policy issues, urged the Corps in an October report to incorporate the views of other federal agencies with expertise in hurricane assessment and flood protection, something it had failed to do.

The Corps says it has since done so.

Some of the criticism is "misleading," said Ed Link, a University of Maryland professor who is leading the Corps' investigation.

Link, who spent much of his career in the Corps, acknowledged that the risk analysis is well behind schedule and said his team had underestimated the difficulty. But he said the Corps always intended to give the public the information that the NRC says is missing.

Originally, the Corps planned to run 2,000 hurricane scenarios through supercomputers, using a simplified mathematical model to predict how those storms would affect New Orleans. The NRC told the Corps it should use a more sophisticated model that had been developed to analyze Hurricane Katrina.

The sophisticated model, applied to 2,000 possible hurricanes, would have taken too long. So the Corps has reduced the number of hurricane scenarios to 150 and hopes to complete that work by February.

"I think we are going to get better results," Link said.

Wayne Clough, chairman of the NRC review panel and president of the Georgia Institute of Technology, said he is waiting to see if the Corps will satisfy his panel's concerns.

"It is challenging for them," Clough said. "They have good people, and they are taking suggestions."

Perhaps the sharpest criticism has come from academicians led by two UC Berkeley engineering professors, Raymond Seed and Robert Bea. Since the early days after Katrina, Seed and Bea have dogged the Corps with their own technical investigation, financed with grants from the National Science Foundation.

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