The Imperfect Storm 3
"During the past 40 years the US Army Corps of Engineers has spent hundreds of millions of dollars constructing a barrier around the low-lying city of New Orleans to protect it from hurricanes. But is the system of levees high enough? And can any defense ultimately protect a city that is perpetually sinking -- in some areas at the rate of half an inch per year?"
Much of the preventive effort was spent on preparing, very carefully, for a Category 3 storm.
On a supercomputer at the Corps’s Waterways Experiment Station, in Vicksburg, Mississippi, engineers run AdCirc simulations of Hurricane Betsy and of Hurricane Andrew, a category 3 storm when it hit Louisiana in 1992. It takes roughly an hour to run the calculations representing 24 hours in the life of the storm. ... Jay Combe, a Corps engineer in charge of the modeling effort, meets every six months with an advisory panel composed of several of the world’s premier modeling experts to review the results. ... Combe says that point should be reached this summer. "I think we’re getting close to the right answer," he says. "But I want to feel totally confident. And I want our outside review team to feel that this is the best we can do with the state of the art right now."
As for Category 4 storms like Katrina, the only defense was to pray nothing wicked that way came for three decades.
"any concerted effort to protect the city from a storm of category 4 or 5 will probably take 30 years to complete. And the feasibility study alone for such an effort will cost as much as $8 million. Even though Congress has authorized the feasibility study, funding has not yet been appropriated. When funds are made available, the study will take about six years to complete. “That’s a lot of time to get the study before Congress,” Naomi admits. “Hopefully we won’t have a major storm before then."
When Katrina showed up, it simply exceeded the designed defenses of city. There was never any prospect they would hold up. Nor was there any possibility any could be built until the middle of the 21st century. Given the length of time necessary to defend the perimeter of New Orleans against a Category 4 threat, a number of proposals were advanced suggesting enclosing the city's vitals in an cofferdam, in a manner reminiscent of battleship citadels.
the amount of time it would take the Corps to construct adequate levee protection against a storm of category 4 ... inspired Suhayda to push for what he calls a community haven project. His idea is for the city to construct a 30 ft (9 m) tall wall equipped with floodgates through the center of town to protect the heart of New Orleans and such culturally important areas as the French Quarter. That portion of the city lies between two bends in the Mississippi River and is therefore already protected by adequate levees on three sides. With its gates closed, the wall would complete a waterproof ring around the area.
But cofferdaming the heart of New Orleans would have left the project open to the criticism that it was protecting property while leaving the poor undefended. Had vital services, communications nodes and power sources been proofed against the flood, extending the analogy of the battleship, the city might have been better able to respond. In the event, there was no citadel against the flood. The article quite presciently anticipated what would happen if people needed to be evacuated from a storm.
For the most part, New Orleans does not have places for people to go. The American Red Cross no longer provides emergency shelters in the city because its officials cannot guarantee the structural integrity of the locations ... that could withstand the forces of a category 4 or 5 storm. ...
Most people would not wish to remain in the city if a category 4 or 5 storm were in prospect, but evacuating could be difficult. Experts say close to 400,000 people could be stranded in the city. There are an estimated 100,000 people without easy access to automobiles, and those who can drive may not be able to do so. ... Complicating the difficulty in New Orleans is the fact that each of the city’s three major evacuation routes is over or near water.
They got that one right.