Engineers on Saturday were tracking roughly 250 seepage points along the levees that line the Mississippi and Atchafalaya rivers. The levees sit on fine sand that lets the river water escape like a convict tunneling out of prison. The water can pop up a mile away. Left to its own devices, one of these sand boils (where water erupts as if from spring) can undermine a levee and lead to a crevasse, a full levee failure — and disaster.
There’s a war underway, fought across the Mississippi’s 35,000-square-mile alluvial plain. This is the toughest test since 1973 of the Army Corps of Engineers’ flood-control system along the Mississippi, which drains 41 percent of the land in the lower 48, and is now swollen by snowmelt from the Rockies and rainwater from the soggy Ohio River Valley.
For the moment, engineers seem to have the upper hand. They are not claiming victory, however. This is not simply a big flood but also a long flood, one that will last well into June. A flood exists in four dimensions, including time — because a long-duration flood can be more problematic than one that crests and recedes quickly.
“Everything that is part of our toolbox is in use,” reports Col. Ed Fleming, New Orleans district commander for the Corps. “There’s no doubt there is going to be a long crest.”
His colleague Mike Stack, chief of emergency management for the Corps at New Orleans, says, “The system is under tremendous stress, and it’s going to be that way for a while.”
Stack added: “It’s performing as it’s designed.”
‘Dealing with earth’
But as 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.”