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. 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. 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. On a tour Tuesday, researchers...showed a "debris line" that indicates the top height of Katrina's waves was at least four feet below the crest of Lake Pontchartrain's levees. They contended that the pattern of destruction behind the breaches was consistent with a localized "pressure burst," rather than widespread overtopping. Former representative Bob Livingston, (R-La.)...noted that the earthen levees along Lake Pontchartrain had all held, while concrete floodwalls had failed. He was especially concerned about the 17th Street barrier, saying it "shouldn't have broken." If Katrina did not exceed the design capacity of the New Orleans levees, the federal government may bear ultimate responsibility for this disaster.

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