DESIGN flaws or faulty construction were to blame for the failure of New Orleans flood defences in the wake of Hurricane Katrina, experts believe.
They rejected the official explanation that storm-water surges caused them to collapse and said the decades-old levee system should have kept the city dry.
Ivor van Heerden, deputy director of the Louisiana State University Hurricane Centre, said the real scandal of Katrina was the "catastrophic structural failure" of the barriers. "We are absolutely convinced those flood walls were never overtopped," he told the Washington Post.
The Army Corps of Engineers has claimed that storm surges topped the concrete walls near Lake Pontchartrain and then undermined the levees they sat on, sending water cascading into the city.
The walls were never tested for their ability to cope with such powerful cascades of water because of budget restraints, officials claim.
Congress had only authorised a flood control system to handle a Category 3 storm and Katrina was a Category 4 when it hit the Gulf coast.
Army spokesman Paul Johnston said there would be a full investigation. Experts pointed to a "debris line" which they said showed the maximum height of Katrina's surges was at least four feet below the top of the levees.