"Why New Orleans is sunk" Excellent article on NO hydrology & the "bowl" topology

I kept wondering how this New Orleans “bowl” scenario eveyone is talking about manifested itself. Here a good explanatory Salon article.
Why New Orleans is sunk

Given what’s happened in the last week, I don’t think that this is either mundane or pointless. It’s factual, and neat enough (IMHO) to be in GQ (even if it’s not a question).

Nice article, very informative.