Katrina scenario was known...

Per Chertoff: Katrina scenario did not exist,

Defending the U.S. government's response to Hurricane Katrina, Homeland Security Secretary Michael Chertoff argued Saturday that government planners did not predict such a disaster ever could occur. But in fact, government officials, scientists and journalists have warned of such a scenario for years. Chertoff, fielding questions from reporters, said government officials did not expect both a powerful hurricane and a breach of levees that would flood the city of New Orleans. "That 'perfect storm' of a combination of catastrophes exceeded the foresight of the planners, and maybe anybody's foresight," Chertoff said.

But in Sinking City of Venice, a NOVA program, which aired in November of 2002,

NARRATOR: Storms push water into the city, forcing pedestrians to use impromptu high-rise sidewalks until the water drains back out to sea. But as spectacular and destructive as Venice's high waters can be, some experts fear New Orleans geography may invite larger floods. Joseph Suhayda, Coastal Engineer: The flooding that threatens Venice is of a more chronic nature. New Orleans would be subject to a high level of threat associated with a hurricane storm surge that could in fact devastate or destroy the city. NARRATOR: That's because 70 percent of New Orleans is below sea level. In the event of a very severe hurricane—category 4 or 5—the city's levee system would not be able to keep massive surges out. The possible result of this nightmare scenario: a city drowned under more than 20 feet of water in places. A worrying prospect for New Orleans, which, like Venice, is engaged in a constant struggle with nature. (emphasis added)