|Birds Point-New Madrid Floodway operation, from undated Mississippi River Commission report.|
Today I interviewed Jonathan Remo, a geoscientist at SIU-Carbondale. He and colleague Nicholas Pinter are accomplished experts on big river flooding and flood control engineering, with ongoing projects on the Middle and Lower Mississippi and a deep body of published work. Pinter’s 2005 Policy Forum paper in Science is a good starting point.
Thanks to Jonathan and Nicholas for help with this post.
Tonight the Mississippi River at Cairo (we say it KAY-roh) at 61.44 feet, nearly two feet above the 1927 record stage. The Lower Mississippi (which begins at the Ohio confluence at Cairo) will see record flooding, at least on the upper reaches of the Lower Mississippi. The levees there are old and untested; the Ohio did not flood in 1993 and the Lower Mississippi was spared.
The Birds Point Levee – Cairo conflict may end up as a footnote when this flood is over.
I hope to do a series of posts here covering scientific and technical issues neglected by the media and to shed some scientific light on what is an unsustainable flood control policy for much of the Mississippi River. (This is close and real for me; tonight I could grab my canoe, put in a few meters from my house onto backwater from the record high Big Muddy River, and get to New Orleans)
Word has just come from the Army Corps of Engineers (COE) will use explosives at Birds Point to put the floodway in operation. No novelist could imagine a greater confluence of race, class, nature, politics and 250 tons of explosives, now to be set off in the middle of the night. This is why our flood control policy is flawed. Floods create vast human drama and misery. We overreacted during them, and immediately after, and then forget.
Yesterday the Nature Conservancy’s Jeff Opperman posted an excellent piece on the history and politics of the Birds Point-New Madrid floodway. He notes the “blowing up of Birds Point” is not the last minute, desperate plan the media have portrayed, but a well-known one going back to 1927. The floodway was operated, with some assistance from dynamite, in 1937. The farmers in the floodway live there knowing this plan exists, as recently as 1983 the COE came very close to opening it, and in 1987 local politicians, with much publicity, tried to get the COE to build a different system. All this is documented in a recent report by the Mississippi River Commission here.
The function of the Birds Point-New Madrid Floodway is well known to local residents, and farmers in the floodway were compensated by the Federal Government for flood easements. The floodway was paid for a long time ago.
Jonathan noted that state and local policy in Missouri, which somehow allowed about 100 houses to be built in the floodway, shares blame. In the 1980’s I worked as a river scientist in Missouri. I ran into strong Libertarian leanings, and some of the most hard-core of those folks farm land protected by big Federal levees. Who want government to leave them alone.
Something to address in our current national debate on budget deficits and entitlements? More on that in another post.
The Birds Point-New Madrid Floodway is part of a Lower Mississippi flood control system that includes several such floodways as an alternative to higher, more expensive, and more dangerous (when they inevitably fail) levees required to carry the design flood. The system was conceived and built after the devastating 1927 flood that made clear to engineers of the day that a “levees only” approach was unworkable.
The Birds Point – New Madrid floodway shunts about 550,000 cfs out of the Mississippi channel, and the levees that constrict it and raise river stage, onto its former floodplain. Recent analysis by the COE says this could drop stage at Cairo by seven feet. Cairo is now seeing about 900,000 cfs from the Upper Mississippi Basin 1,350,000 cfs from the Ohio.
Tonight the levees in Cairo are not in good condition, sand boils have formed and the city is under mandatory evacuation orders. Jonathan noted that 63.0 feet at Cairo – the current peak prediction – would not overtop the levees, but given their pre-flood condition and the length of the flood, would almost certainly cause them to fail.
Worst case: They might still fail after the COE opens the floodway tonight. We could see 100 houses lost in the floodway, much damage to farmland, and loose Cairo as well.
I’ll end this with a few of Dr. Remo's observations. At record stages, the discharge-stage relationship is unknowable. We can model this on smaller rivers, but a half-mile wide Mississippi at record stage is too complex. So prediction of flood elevations with increasing discharge becomes very difficult. Especially at confluences, and at Cairo now we have the mother of all confluences.
We’re witnessing the beginning of an unprecedented test of an 80-year-old flood control works on the Lower Mississippi River. Regardless of what happens at Cairo tonight, the system below it is old, not in good shape, not well understood, and about to see record flooding.