May 22, 2011


Flooding threat along Mississippi River is a test of man vs. nature (Joel Achenbach, May 21 , 2011, Washington Post)

[A]s with any complex system of engineering, there are weak points, question marks, vulnerabilities. Powerful forces are being checked with levees made of clay.

Four barges carrying Midwest grain broke loose Friday in Baton Rouge, and two of them sank. That shut down the river for five miles and kept officials fretting well into Saturday as they worried that one of the barges might plow into a levee and create a breach.

“That system is designed to handle the river and the pressure of the river. It is absolutely not designed to handle a barge hitting it,” Steve Wilson, president of the Pontchartrain Levee District, said Saturday.

“We’re not dealing with digital technology. We’re dealing with earth,” said Joseph Suhayda, a retired Louisiana State University coastal hydrologist. “This goes back to the beginning of civilization. It’s available, it’s cheap, but it’s not very good material.”

He went on: “These seepages and sand boils are reflections of the fact that there are some continued deficiencies in the system. This is not a robust system. It’s not concrete.”

The Army Corps has long prepared for a hypothetical inundation known as the Design Flood. This flood pretty much fits that template. The flow, measured in cubic feet per second, isn’t quite at Design Flood levels, but there are places where the river gauges have measured record-high water, busting the old mark by three feet in some spots.

For years, the smart money has bet that, in the protracted wrestling match on the Mississippi between man and nature, nature will ultimately come out on top. The decision, going back to the 19th century, to imprison a naturally meandering river between levees — parallel Great Walls of China, to use the common analogy — has the inevitable effect of raising the water level downstream. Even at normal stages, the river stands up “like a vein on the back of a hand,” as John McPhee wrote in his 1989 best-selling book “The Control of Nature.”

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Posted by at May 22, 2011 8:49 AM

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