That's where city/state cooperation and planning was crucial -- there needed to be inland shelters in schools and public buildings -- but if Gov. Blankhead ever thought of doing that she must have balked at the idea of trying to empty NOLA all over the state..... even though she had to KNOW that without a realistic evac plan the results would be just the sort of catastrophe we have seen. In fact, horrible as it was, this fell far short of the real potential catastrophe: Katrina could have remained a strong Category 5 and could have hit NOLA directly up the Mississippi and crushed the entire city immediately with a 25-30 foot storm surge. NOLA actually got 'only' a glancing blow compared to what could have happened, and 100,000 could have been dead due to the dereliction of the LOCAL and STATE officials.
It really could have been much worse for NO. It could have been done, not easily or cheaply but still possible if all state resources would have been used to shelter people. I honestly think that she didn't want to spend the money required to do so.