What do you mean, it was a surprise?
Contrary to what some people will have you believe, the Katrina effects on New Orleans were to be expected in a way. Of course, after a tragedy of such scale it would be too easy to say '...told you so...', but still... Read the beginning of this article from National Geographic and then check out the date it was written... October 2004 . Almost eerie... Now let's see if history will teach us something...