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Replumbing Louisiana

I wonder if Hurricane Katrina might not be just the opportunity we need to reroute the Mississippi River.

Major rivers carry huge loads of sediment, which settle out of them as they reach level coastal areas. This deposition leads, over long periods of time, to shifts and branches in the river's course. In the case of the Mississippi, the river wants to jump out of its current channel into the Atchafalaya River, which would send it to a point further west on the Louisiana coast than its current mouth. We had invested so much in building up New Orleans and other cities along the original lower stretch of the Mississippi that it would be catastrophic if the river ever crossed into the Atchafalaya. So the Army Corps of Engineers has built massive engineering structures to keep the Mississippi in the course where the first European settlers found it.

But like most of the Corps' major hydrological projects, holding the Mississippi in its channel can't last forever. Eventually the shifting sediments of the river valley, perhaps triggered by a major storm that passes a bit further west than Katrina, will undermine our best dams and levees. The people currently living along the Atchafalaya will be wiped out, while the rebuilt New Orleans will be left stranded.

Right now, though, southern Louisiana is already in shambles. New Orleans will not regain its former size an importance for many years, if ever. Katrina has already destroyed so much of what a jump into the Atchafalaya has destroyed that deliberately breaching the dam will add little to the recovery costs. And it will save us from a long, expensive, and futile battle to keep the river where it is.

Of course, this is politically unfeasible. In the wake of a disaster, there is a strong impulse to erase the disaster, to put everything back just like it was. A fully rebuilt New Orelans, including the Mississippi, would be a psychologically satisfying statement of "ha, mother nature can't keep us down" -- while ironically setting us up for a rough answering blow in the longer term. And while we might reluctantly accept a permanent change in the landscape wrought by nature, a direct human decision to do so will face stiff opposition. Finally, the Atchafalaya valley is not quite so wiped out as New Orleans, and thus would face significant added hardship (though they'll face it eventually regardless) -- the very eastward turn that kept Katrina from rerouting the Mississippi herself also spared the Atchafalaya valley from her worst damage.


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