Does anyone know about the Atchafalaya River through Morgan City and the tale that used to be told in those parts: I spent some time there 25 years ago, and locals said that the Atchafalaya was the likely future course of the Mississippi River if nature ever had her way.... I was told that the potential existed for the entire lower river basin to be re-routed through what is now the Atchafalaya.... if something like that could result from Hurricane Katrina the devastation would be off the charts... but I don't know if that's a serious possibility or a foolish rumor.... am looking for info on the Internet.
http://www.lacoast.gov/geography/at/atch_basdyn.htm
Actually were it not for human-built structures the Mississippi would ALREADY be going down the Atchafalaya;
Over time the Mississippi naturally switches around its exit in the delta,We've been artificially preventing it from switching from New Orleans to the Atchafalaya.
The Old River control is most likely to go with spring flooding with extra high water coming down river...
I can't comment on the eventual course of the Mississippi, but I'd say the chances of having a navigable channel on Tuesday are zero in the absence of a Dennis-like weakening before landfall.
Miles and miles of windblown sand in the wrong place that all has to be dredged before the Mississippi opens up again.
The Old River Control Stucture is far enough up river that there is no risk of this. About 30 years ago seasonal flooding almost washed out the structure, but it has been beefed up since then. The Morganza structure is farther downstream than Old River, but it shouldn't be at risk either.