Why Does It Flood When Levees Don’t Break? And Other Questions. Part 2

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Bigger Pie Forum | Why Does It Flood When Levees Don’t Break? And Other Questions. Part 2 | Kelley Williams
 
Q.  What went wrong with changes to the river intended to control flooding?
A.  Wrong focus. Politics trumped engineering. Unintended consequences.  The changes focused on containing floods and preventing levee failures instead of minimizing and discharging floods. Result: higher levees and higher floods. The Corps says $14 billion spent on the MR&TP has saved a trillion dollars in flood damages from prevented levee failures and has a benefit to cost ratio of 70:1.  It counts imaginary savings and ignores real damage from floods without levee failures.  The Corps builds levees 3 feet higher than floods to provide a margin of safety.  It keeps raising levees as the river keeps rising. Where does it end?  Will levees grow to the sky?
 
Q. What else went wrong?
A. Politics trumped engineering.  Cutoffs were intended to minimize floods by speeding them to the sea.  Faster floods are lower and shorter.  Sixteen cutoffs completed in the mid 40’s shortened the lower river 152 miles, and made it steeper.  They worked as intended for a while.  The river was so benign in the 1950’s that Congress passed the 1954 Flood Control Act (FCA) to keep the river’s flow to the Gulf like it was in 1950.  Congress tried to lock the river in a time capsule.
But the river broke out.  In 1950, 77% of its flow discharged to the Gulf at New Orleans via the main channel.  The other 23% flowed down Old River (a natural channel north of Baton Rouge) to the Atchafalaya River and then to the Gulf at Morgan City, LA.  This is a shorter steeper path to the Gulf than via New Orleans.  As flow downriver increased due to cutoffs and other changes, flow down Old River naturally increased.  When

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