A geologist friend of mine says the Mississippi River has been trying to change coarse for the last 50 years. He says that the levees merely "convince" it to go where we want it to go.
I am a licensed professional geologist, although not in Louisiana (LA does not have P.G. licensure). The talk among geologists is astonishingly different from what you hear elsewhere. There's little surprise at recent events, since it's well known that coastal LA has been fighting natural progression for a long time...and that's an expensive and losing game.
To me, hearing talk of rebuilding NO is like listening to a drunk driver crawling from a crash and asking for a drink and another set of car keys.