Posts tagged Louisiana

Mississippi River Project Design Flood Diagram

The Flood of 2011 on the Lower Mississippi this spring has fascinated me to no end.  I’ve been reading lots of news and blogs on the subject as well as digging into other websites of the US Army Corps of Engineers to learn more about this complicated, engineered river system.

Through this I came upon a diagram of the river that is really informative.  It visually describes how floodwaters move through the lower Mississippi basin by depicting the river and its tributaries as a tree – with branches sized in scale with the amount of flood flow they are able to carry.

Here are some of the things I find surprising:

1. The flood flow of the Mississippi above Cairo, Illinois is TINY.  Most of the flow comes from the Ohio River.  Even the Tennessee River carries more flood flow than the middle Mississippi.

1. The bulk of the capacity of the river is in the middle section between Helena, Arkansas and Vicksburg, Miss rather than at the bottom of the system.

1. The river sheds half of its water into the Atchafalaya River Basin through the Old River and Morganza Spillways leaving a much smaller amount of water to continue past Baton Rouge and New Orleans.