America's Achilles Heel

May 17, 2019 12:39 PM

Rising up from the flat, wooded west flood plain of the Mississippi River are four massive concrete and steel structures that would make a pharaoh envious: the U.S. Army Corps of Engineers’ greatest work, the two billion-dollar Old River Control Structure (ORCS). The ORCS saw its second highest flood on record in March 2019, and flood levels have risen again this week to their fifth highest level on record. While the structure is built to handle the unusual stress this year's floods have subjected it to, there is reason for concern for its long-term survival, since failure of the Old RIver Control Structure would be a catastrophe with global impact.

Failure of the ORCS and the resulting loss of barge shipping that might result could well trigger a global food emergency. The U.S. is one of the world’s largest exporters of grain, and 60% of that grain is transported to market by barges travelling on the Lower Mississippi River. A multi-month interruption in the supplies of more than half of U.S. grain to the rest of the world can be expected to cause a spike in global food prices, and potentially create dangerous food shortages in vulnerable food-insecure nations.

Dr. Jeff Masters writes a three-part series on the Old River Control Structure (previously) for Weather Underground:

1. America's Achilles' Heel: the Mississippi River's Old River Control Structure
2. Escalating Floods Putting Mississippi River’s Old River Control Structure at Risk
3. If the Old River Control Structure Fails: A Catastrophe With Global Impact

posted by ragtag (15 comments total)

This graphic on the Wikipedia page is especially helpful for understanding why the Red River wasn't, then was, and now isn't a tributary of the Mississippi and why this is where the Old River Control Structure was built.

An interesting mention in the articles is the 700 year old logjam on the Atchafalaya River that was cleared in the mid 1800s. Once gone, the Atchafalaya became a more attractive route for the Mississippi.
posted by theory at 1:01 PM on May 17, 2019 [11 favorites]

Background on USACE (the river control people) and their past obvious failures. Now, off to TFA...
posted by j_curiouser at 1:03 PM on May 17, 2019 [2 favorites]

There was a docu on how the Army Corps built a 200 acre hydraulic scale model of the Mississippi Basin as part of the lock works. Interesting stuff.
posted by msbutah at 1:06 PM on May 17, 2019 [4 favorites]

The previously links to the relevant John McPhee article (which became one-third of Control of Nature).
posted by Quasirandom at 1:21 PM on May 17, 2019 [13 favorites]

I’m a local that moved back to New Orleans and brought my girl with me and it’s fun to take her to see real “behold the power of engineering!” Stuff like the Bonnet Carre. You can read that the gate structure is a mile and a half long but it’s only when you stand there and watch them open the gates that you really get a feel for it. Just the audacity of binding one of the world’s great rivers just a relative few decades ago and now we can’t even agree to fix highways or roads. It’s a spectacle.

Likewise the entire citywide/regional feeling of “we know this place can’t possibly stand against nature”—because people do know! We’re not stupid!—combined with “but it’s been here 300 years, we’ll figure something out” is a trip.
posted by Ghostride The Whip at 1:23 PM on May 17, 2019 [16 favorites]

There was a docu on how the Army Corps built a 200 acre hydraulic scale model of the Mississippi Basin as part of the lock works. Interesting stuff.
posted by msbutah at

Crucially, that model did not include the lower half of Louisiana, so the ecological impacts of cutting off sediment to the lower half Louisiana were never evaluated by the corps.

There was just posted and reposted to the blue in article on how Louisiana's map has changed which is very incorrect, and it's these kinds of mistakes and omissions tthat prevent people from getting a clearer idea how exactly the Lower Mississippi River Delta works.

That said I really like Jeff Masters' article because he refers to the most up-to-date climatology and its impact to the river, as well as the most up to date geomorphology from LSU.

Shreve's cut inevitably lead to all of this.

But it is solvable, and more than that it is worth solving because of the tremendous ecological benefits of the Mississippi River delta and the Atchafalaya basin. There are trillions of dollars of natural capital in these systems. (and maybe even ivory-billed woodpeckers) But because the corps and the United States continually refuse incorporating any kind of ecological economics into any of their cost-benefit decisions, correcting these problems and maintaining the M R and T is always a struggle when they have to go to Congress.

But we also keep missing the opportunity to talk about the grand hubris of engineering. Authors like Jeff Masters and Elizabeth kolbert bring up the fragile nature of even these mighty structures but neither of them are talking about the fragile nature of the massive petrochemical infrastructure just a few miles south. That petrochemical infrastructure is also highly vulnerable to fresh water shortages, temperature changes, River levee breaches, and hurricane surges, as well as the new Gulf deluges, the massive rains that come from an overheated Gulf of Mexico.

The USA is building, with taiwan's help, another huge Plastics facility in St James Parish, when St James Parish has been under flood alert 3 times this year alone.

It's like that TV series True Detective, where there everyone is just talking past the biggest issues and the biggest culprits and killers on the landscape.

I can't tell if it's horribly ironic or just horribly stupid that the petrochemical plants that are causing most of the climate problem are creating and increasing their own risk exponentially with every passing year.
posted by eustatic at 1:48 PM on May 17, 2019 [28 favorites]

I recall reading John McPhee about 30 years ago, regarding the control of the Mississippi. This was in conjunction with driving through Louisiana, and over the Atchafalaya and Mississippi rivers. The impression I got at the time was that the task was impossible, and absolutely necessary. Since then I have learned a lot about the ecology of Louisiana, and how the powerful are allowed to do what they want by the corrupt. There is a huge potential for good outcomes, but the chance of complete disaster is so high, too. All that it would take would be a Havey size hurricane in the Delta, and nothing that man has built could keep the river from moving.

If the highways and pipelines that cross the rivers were cut by the failure of the control structure, then the economic impact would be huge. The big question is how to move the silt to the places that absolutely need it, such as the lower delta.
posted by Midnight Skulker at 2:05 PM on May 17, 2019 [4 favorites]

There was a docu on how the Army Corps built a 200 acre hydraulic scale model of the Mississippi Basin as part of the lock works. Interesting stuff.
posted by msbutah at

Crucially, that model did not include the lower half of Louisiana, so the ecological impacts of cutting off sediment to the lower half Louisiana were never evaluated by the corps.

They still quite casually do this kind of stuff today. I run past an example of it, every couple of days, on the Chicago lakefront where the Fullerton park extension out into the lake was done in conjunction with the Army Corp of Engineers two years ago and is now leading to the erosion of two of the neighboring beach sections and near constant flooding of the pedestrian footpath every time the wind is from the north (no matter how feeble it is - it used to take real storms for this). Fortunately, there are several more sections of but still seems like really sloppy thoughtless work.
posted by srboisvert at 2:53 PM on May 17, 2019 [2 favorites]

Thanks for posting this. the mil engineers do some useful research but these one-hit interventions... there's no redundancy in this.

In a few hours I'll lead a workshop on the intersection of stormwater and climate change and how we little people can respond and do stuff. It's based on small things scaling up and linked as much as possible with lots of redundancy - pretty standard low-impact design ... but

engineers I meet know almost nothing of such and dismiss them as; too small for effect; dislike of soft systems; bias against natural solutions; the necessity of working with other disciplines. Of course it's hard to monetise lots of small things.
posted by unearthed at 3:37 PM on May 17, 2019 [4 favorites]

The previously links to the relevant John McPhee article (which became one-third of Control of Nature).

Highly recommended reading for anyone who enjoyed the links in this FPP. Set some time aside for it.
posted by TrialByMedia at 7:50 PM on May 17, 2019 [3 favorites]

on April 14, 1973, the Old River Control Structure foreman walked out on the Low Sill Structure for an inspection, and witnessed the collapse of a 67-foot-long wall along the south side of the intake channel ... In the end, the Low Sill Structure was saved but was permanently damaged, and can now only handle 60% of the flow it once could.

So, in 45 years, nobody's been willing to throw the necessary money at this to bring it back to the original capacity? Or it was damaged in an unfixable way? Not that it should be fixed; it sounds like the change is happening no matter what, and the option is between "we control the speed and some direction of change" or "it happens catastrophically overnight when we're not expecting it."

The weird part is, the science behind the changes doesn't seem to directly connect to the global warming that the R's are so devoted to denying. River runs through channel, hauls dirt down channel, channel gets clogged up, river jumps to new channel. There may be more flooding now because of (ahem) The Topic That Shall Not Be Named In Government Reports, but the basic principles say it's just a matter of time.
posted by ErisLordFreedom at 10:59 PM on May 17, 2019

So, in 45 years, nobody's been willing to throw the necessary money at this to bring it back to the original capacity? Or it was damaged in an unfixable way?

My understanding of it is that the structure was significantly undermined, and it was shored up by pumping mortar and rocks into the cavity below the structure. Repairing it would probably involve demolishing the entire structure and rebuilding it. Building other nearby structures allowed them to relieve enough pressure on the existing structure to prevent further damage while simultaneously increasing the handling capacity of the system.
posted by TrialByMedia at 7:10 AM on May 18, 2019 [1 favorite]

I have to wonder what thought has been put to the possibility of an 8+ quake on the New Madrid fault? the river was thrown 30 miles out of its bed 200 years ago by the quakes there. the scale of the destruction could be unbelievable...
posted by supermedusa at 10:01 AM on May 18, 2019

With New Orleans needing the Mississippi ORCS to cover its back, while to the front, storm-force strength is rising, while it's also under sea level while oceans rise, it seems like it's at significant risk of becoming an early example of a major city becoming partly untenable in the changing climate. The article mentions there are supporters of an orderly transition of the Mississippi, giving people and infrastructure time to adapt. I suspect the ORCS isn't the only reason for doing that.
posted by anonymisc at 12:58 PM on May 18, 2019

Thanks! This is such a great story.
posted by sneebler at 7:42 PM on May 18, 2019