New Orleans flood risk lower, not erased

The federal government released its long-awaited risk assessment for New Orleans on Wednesday, saying the city is safer than it was before Hurricane Katrina but still faces a 1-in-100 chance each year of significant flooding -- a prospect that could undermine the city’s future.

After a scientific investigation, the Army Corps of Engineers released flood maps showing the risks from hurricane-triggered surges to each home and business in New Orleans.

The maps distill the city’s vague sense of impending danger to a stark reality.

The assessment means that over the span of a 30-year mortgage, homeowners in neighborhoods that are below sea level and vulnerable to hurricane surges would have a greater than 25% chance facing a serious flood.

“It is difficult for a lot of people to accept those levels of risk,” said Greg Rigamer, an urban planner with GCR & Associates Inc. who is involved in the city’s redevelopment efforts. “These are some pretty scary projections.”

The government’s risk assessment confirms what many insurers have already concluded: The city faces clear danger.

Homeowners and businesses have been struggling with soaring insurance rates, which in some cases have doubled or tripled since Katrina.

The higher rates, along with rising construction costs, are hindering efforts to rebuild residential neighborhoods.

Former residents are trickling back but at a slowing rate. The city’s population is 262,000, compared with 454,000 before Katrina.

Senior corps officials said it was not their place to tell the public whether the flood risks were acceptable but rather to give the city the best analytical tools to plan its future.

“Everybody has to answer that for themselves,” said Ed Link, a University of Maryland civil engineer who led the investigation.

Link said that the levee system was providing the city with the best protection it had ever had and that it would continue to get better. The corps hopes to complete repairs and upgrades to the 350-mile levee system by 2011.

The projections are based on a complex mathematical model of 152 hypothetical hurricanes that could hit the city, ranging from minor storms to blockbusters that occur once every 5,000 years, Link said.

The new tool represents a breakthrough in determining the risk that specific homes and businesses face, allowing users to enter addresses onto a website and get a satellite image of their neighborhoods with projected flood depths.

Such risk assessments and computerized maps are likely to spread across the country.

They could disclose the risk that every person in Los Angeles or San Francisco faces from an earthquake collapsing their home or office.

Such news might not be welcome. The earthquake risk in San Francisco may be comparable to the flood risks in New Orleans, warned Patricia Grossi, an expert at Newark, Calif.-based Risk Management Solutions, which has monitored the corps’ work.

Though New Orleans may have better risk information than any city in the world, the maps are delivering a bitter message.

The federal government has committed $7 billion to upgrade the city’s hurricane protection system, reinforcing weak levee foundations, rebuilding concrete storm walls, installing flood gates on drainage canals and upgrading pumping stations.

The depth of potential flooding from future storms is much less than it would have been before Katrina, Link said.

In the affluent Lakeview section, for example, flooding would be reduced by about 5 feet, thanks to improvements to the 17th Street levee. But some sections of Lakeview still could be covered with 6 feet or more of water.

“If you have 4 feet of water in the living room, as opposed to 6 feet, I am not sure how much difference that makes,” said Richard Little, director of USC’s Keston Institute for Public Finance and Infrastructure Policy. “I hope nobody is assured by that.”

Corps officials, however, say such information could help people decide where to buy homes. Or it could help them decide to elevate their homes on pylons.

But the maps also show little reduction in potential flooding in the 9th Ward and Gentilly areas, which were both devastated during Katrina and remain vulnerable.

Outside civil engineering experts say a 1% risk is far too high. Katrina killed 1,293 and caused an estimated $100 billion in damage.

“It is absolutely not an acceptable risk,” said Robert Bea, a civil engineering professor at UC Berkeley who has investigated the Katrina-related levee failures and has become a prominent critic of the Corps of Engineers.

Bea said the corps was underestimating the ongoing risk, because many miles of levees that did not fail during Katrina were never upgraded.

Some New Orleans residents greeted the new corps assessment with a ready rebuttal.

“We don’t want any risk,” said LaToya Cantrell, president of the homeowners group in the Broadmoor district, which was covered by 6 feet of floodwaters after Katrina.

Cantrell said her neighborhood was recovering faster than others in the city, having restored 66% of 2,400 homes. But the perceived risk of flooding is driving insurance rates to horrific levels, ranging between $7,000 and $8,000 per year for homes valued at about $350,000 to $400,000.

That might just be part of life in New Orleans.

“We are never going to be able to say there is no risk of living here,” said Karen Durham-Aguilera, a corps engineer responsible for overseeing the long-term planning and hurricane protection system work in New Orleans.

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ralph.vartabedian@latimes.com