New Orleans – Louisiana’s top hurricane experts have rejected the official explanations for the floodwall collapses that inundated much of New Orleans, concluding that Hurricane Katrina’s storm surges were much smaller than authorities have suggested and that the city’s flood-protection system should have kept most of the city dry.
The Army Corps of Engineers has said that Katrina was too massive for a system that was not intended to protect the city from a storm greater than a Category 3 hurricane, and that the floodwall failures near Lake Pontchartrain were caused by extraordinary surges that overtopped the walls.
But with the help of complex computer models and stark visual evidence, scientists and engineers at Louisiana State University’s Hurricane Center have concluded that Katrina’s surges did not come close to overtopping those barriers.
That would make faulty design, inadequate construction or some combination of the two the likely cause of the breaching of the floodwalls along the 17th Street and London Avenue canals – and the flooding of most of New Orleans.
John Barry – who criticized the Corps in “Rising Tide,” a history of the Mississippi River flood of 1927 – said that if Katrina did not exceed the design capacity of the New Orleans levees, the federal government may bear ultimate responsibility for this disaster as well.
“If this is true, then the loss of life and the devastation in much of New Orleans is no more a natural disaster than a surgeon killing a patient by failing to suture an artery would be a natural death,” Barry said.
In the weeks since Katrina drowned this low-lying city, there has been an intense focus on the chaotic government response to the flood.
Ivor van Heerden, the Hurricane Center’s deputy director, said the real scandal of Katrina is the “catastrophic structural failure” of barriers that should have handled the hurricane with relative ease.
“We are absolutely convinced that those floodwalls were never overtopped,” said van Heerden, who also runs LSU’s Center for the Study of Public Health Impacts of Hurricanes.
Corps spokesman Paul Johnston said Tuesday that the agency still believes that storm surges overtopped the concrete floodwalls near the lake, then undermined the earthen levees on which they were perched, setting the stage for the breaches.
Johnston said the Corps intends to launch an investigation to make sure it is correct about that scenario. But he emphasized that Katrina was a Category 4 hurricane when it smashed into the Gulf Coast, whereas Congress authorized the Corps to protect New Orleans against a storm only up to Category 3. “The event exceeded the design,” Johnston said.
The center’s researchers agree that Katrina’s initial surge from the southeast overwhelmed floodwalls along the New Orleans Industrial Canal, flooding the city’s Lower Ninth Ward as well as St. Bernard Parish. They believe that a little-used Army Corps navigation canal known as the Mississippi River Gulf Outlet helped amplify that surge, although they acknowledge that this surge was larger than the system was designed to control.
But the researchers have strong evidence that Katrina’s subsequent surge from the north was several feet shy of the height that would have been necessary to overtop the 17th Street and London Avenue floodwalls. It was the failures of those floodwalls that emptied the lake into the rest of the city, filling most of New Orleans like a soup bowl.
