...year. One map shows the flood risk that existed just before Katrina. The other shows the areas’ calculated flood risk as of June 1, after repairs and improvements.

Because temporary floodgates have been built to block off the outfall canals that were the source of most of the flooding in Lakeview, the risk reduction in that area is more substantial than what has been accomplished in Gentilly. Although Gentilly also has the benefit of surge gates blocking its outfall canals, it still has weak defenses on the eastern side. Lakeview’s calculated flood-depth risk has been reduced by 5.5 ft. Its estimated property losses have been reduced by 42% and the estimated number of fatalities, in the event no evacuation is possible, has been reduced by 98%.

Tom Sawyer/ENR The Corps is considering other areas, like Sacramento, Calif., for applying risk tools.

In Gentilly, the flood depth has gone down half a foot, property losses decreased by 4.6%, and projected fatalities have been reduced by 89%.

Later this summer, the Corps says it will deliver models to show how risk projections change when further upgrades to bring the system to a 100-year level of protection are completed in 2011.

“We now have a risk assessment for our area that no one else in the country has,” says Karen Durham-Aguilera, director of Task Force Hope in Louisiana, the Corps program responsible for overseeing $5.7 billion worth of long-term planning and hurricane protection system work in southeast Louisiana.  “What an incredible advantage to have this information,” she says.

Van Antwerp says the Corps is considering where next to apply the model. Although there is no rollout date for other areas, “We are already using the technology,” he says. Larry Roth, deputy executive director of the American Society of Civil Engineers, says it will be important to apply the tool elsewhere, particularly for Sacramento, Calif., where there is significant vulnerability from both seismic activity and river flooding. “A hurricane is a severe hazard, but it is one hazard,” he says.