Tuesday, May 03, 2011

Dynamiting levees

Just a reminder. Despite the continuous finger shaking at ninth ward "alarmists" and "conspiracy theorists"* this sort of thing is actually done from time to time.
The Mississippi River at Cairo, Illinois, had dropped about one foot by Tuesday morning, eight hours after the government blew open a levee to relieve flooding in Illinois and Kentucky, a U.S. Army Corps of Engineers spokesman said.

The explosion at 10 p.m. on Monday was expected to flood about 130,000 acres of Missouri farmland and relieve Cairo and other towns threatened with massive flooding where the Mississippi and Ohio rivers meet.
Also important to remember, it doesn't always work the way they say it's going to work.
Carlin Bennett, a commissioner in the rural Missouri county that will bear the brunt of the flooding, said it was a little early to make the call, but was afraid the operation would not drop the river the three to four feet the government wants.

"It's looking like all of our worst fears here," said Bennett, who has 80 acres himself that are being flooded. "Our land got flooded and they are not getting the flooding relief they expected."

If Bennett is right, and this blown levee doesn't relieve the pressure the corps intends it to, we're in for an interesting end of the month downriver.

Maj. Gen. Michael Walsh -- the man ultimately responsible for the decision to go through with the plan-- has indicated that he may not stop there if blasting open the Missouri levee does not do the trick. In recent days, Walsh has said he might also make use of other downstream "floodways" -- basins surrounded by levees that can intentionally be blown open to divert floodwaters.

Among those that could be tapped are the 58-year-old Morganza floodway near Morgan City, La., and the Bonnet Carre Spillway about 30 miles north of New Orleans. The Morganza has been pressed into service just once, in 1973. The Bonnet Carre, which was christened in 1932 has been opened up nine times since 1937, the most recent in 2008.

"Making this decision is not easy or hard," Walsh said. "It's simply grave -- because the decision leads to loss of property and livelihood, either in a floodway or in an area that was not designed to flood."

Officials in Louisiana and Mississippi are warning that the river could bring a surge of water unseen since the Great Mississippi Flood of 1927.

Interesting to see them even name the possibility that the Morganza could be used. If they're actually even considering that, it's a sign that they're worried.

One wonders, also, how long they've been that worried and if, as recently as March 13, they were lying about how worried they were.

The river is projected to crest at 14.5 feet at the Carrollton gauge in New Orleans on March 30. That leaves a bit of freeboard under the 17-foot flood stage, said Michael Stack, chief of emergency operations at the Army Corps of Engineers New Orleans District.

"The current levels are actually more in line with the average for this time of year than they have been over the last few months," Stack said. Quick rises in the river seem to coincide with unusually low levels earlier in the year, he said.

"Levels in January and February were a few feet below the historical averages and some of the lowest we've seen in a while," Stack said.

"The projected crest of 14.5 in New Orleans is a little above average, but not unexpected, as March through early June is typically the high-water season for the river."

*For the record, as I've said before, I don't think any levees were dynamited during the Katrina flood. But I also don't think it's off base for people to raise the question given that it has happened in the past and continues to happen today.

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