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.
