May 14, 2011

Does mighty river know its bounds?

Just how mighty is the Mississippi?

Put it this way, its 1.5 million cubic feet per second flow rate could fill up the current volume of Lake Okeechobee – 2.4 million acre feet worth – in under a day.

Eighteen hours to be exact.

Where did all the water come from?
A big snow melt and the record April tornado-spawning storms.

How mighty is the Mississippi?

Without intervention, the raging river is ready to jump its banks. Better known as Delta Switching, it’s the process by which a river finds a new course to sea. In the case of the Mississippi it happens about every thousand years, or rather past tense – “it happened about every thousand years” – until artificial controls were put in place to keep the channel in place at Baton Rouge and south from there through the port town of New Orleans.

Where it’s itching to go instead is into the Atchafalaya.

It’s a shorter and straighter and stepper path to sea and during normal times, it still gets a third of the Mississippi’s flow, as diverted through the Old River Control Structure.

How mighty is the Mississippi?

The emergency spillways upstream at Morganza are open for the first time since 1973. (See article.) That sends half the raging water into the Atchafalaya and, in the days to come, will inundate hundreds of thousands of acres of farmland and flood out thousands of homes.

That’s a big price to pay, but miniscule to the alternative:

A permanent relocation of the river channel down the Atchafalaya instead.

Losing Mississippi's sediment load to sea
is causing coastal Louisiana to sink!

That’s one mighty river!

No comments: