Corps’ risk analysis slammed

When the Army Corps of Engineers admitted last 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 will 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.

The stakes are high, not only for the integrity of the levees around New Orleans but of similar levees that protect millions 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 delta, which has 2,300 miles of levees that protect cities and farmland.

The Corps is about six months behind schedule in issuing a “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 gotten more intense 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 whole 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, 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 has failed to do previously. The Corps says it has since done so.

Some of the criticism is “misleading,” says 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 possible 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 January or February.

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

While the Corps has struggled with its risk analysis, a private company recently published its own New Orleans risk assessment with some potentially troubling findings for the city’s future. The analysis was done by Risk Management Solutions of Newark, Calif., which provides catastrophic risk analysis for the insurance industry.

The report found evidence that growing hurricane intensities, geologic subsidence along the Gulf coast and rising sea levels have raised the long-term threat to New Orleans. In an examination of some neighborhoods, it found the highest-risk areas could require insurance premiums of $14,000 per year, said Patricia Grossi, one of the report’s authors.

Even now, the Corps is attempting to improve the levee system so that by 2010 it might fail on average only once every 100 years, a standard that seems weak to many experts.

“Is it acceptable to have the worst natural disaster in U.S. history occur over and over again?” asks David Daniel, president of the University of Texas at Dallas and the leader of the American Society of Civil Engineers team reviewing the Corps’ Katrina investigation. “I don’t think it is.”