America's Achilles' heel: the Mississippi River's Old River Control Structure

By: Dr. Jeff Masters , 5:20 PM GMT on May 13, 2011

Share this Blog
20
+

America has an Achilles' heel. It lies on a quiet, unpopulated stretch of the Mississippi River in Louisiana, a few miles east of the tiny town of Simmesport. Rising up from the flat, wooded west flood plain of the Mississippi River tower four massive concrete and steel structures that would make a Pharaoh envious--the Army Corps' of Engineers greatest work, the billion-dollar Old River Control Structure. This marvel of modern civil engineering has, for fifty years, done what many thought impossible--impose man's will on the Mississippi River. Mark Twain, who captained a Mississippi river boat for many years, wrote in his book Life on the Mississippi, "ten thousand river commissions, with the mines of the world at their back, cannot tame that lawless stream, cannot curb it or define it, cannot say to it "Go here," or Go there, and make it obey; cannot save a shore which it has sentenced; cannot bar its path with an obstruction which it will not tear down, dance over, and laugh at." The great river wants to carve a new path to the Gulf of Mexico; only the Old River Control Structure keeps it at bay. Failure of the Old River Control Structure would be a severe blow to America's economy, interrupting a huge portion of our imports and exports that ship along the Mississippi River. Closure of the Mississippi to shipping would cost $295 million per day, said Gary LaGrange, executive director of the Port of New Orleans, during a news conference Thursday. The structure will receive its most severe test in its history in the coming two weeks, as the Mississippi River's greatest flood on record crests at a level never before seen.


Figure 1. Two views of the Mississippi River. Left: the meander paths of the Mississippi over time, as published in "Geological Investigation of the Alluvial Valley of the Lower Mississippi River" (Fisk, 1944). Right: The Army Corps of Engineers' view of Mississippi River peak flow rates during a maximum 1-in-500 year "Project Flood" (U.S. Army Corp of Engineers, 1958.) The places outlined in red are where the Corps has built flood control structures capable of diverting a portion of the Mississippi's flow.

A better path to the Gulf
The mighty Mississippi River keeps on rollin' along its final 300 miles to the Gulf of Mexico south of New Orleans--but unwillingly. There is a better way to the Gulf--150 miles shorter, and more than twice as steep. This path lies down the Atchafalaya River, which connects to the Mississippi at a point 45 miles north-northwest of Baton Rouge, 300 river miles from the Gulf of Mexico Delta. Each year, the path down the Atchafalaya grows more inviting. As the massive amounts of sediments the Mississippi carries--scoured from fully 41% of the U.S. land area--reach the Gulf of Mexico, the river's path grows longer. This forces it to dump large amounts of sediment hundreds of miles upstream, in order to build its bed higher and maintain the flow rates needed to flush such huge amounts of sediment to the sea. Thus the difference in elevation between the bed of the Mississippi and the Atchafalaya--currently 17 - 19 feet at typical flow rates of the rivers--grows ever steeper, and the path to the Gulf down the Atchafalaya more inviting. Floods like this year's great flood further increase the slope, as flood waters scour out the bed of the Atchafalaya. Without the Old River Control Structure, the Mississippi River would have carved a new path to the Gulf in the 1970s, leaving Baton Rouge and New Orleans stranded on a salt water estuary, with no fresh water to supply their people and industry.

History of the Old River Control Structure
The Mississippi River has been carving a path to the ocean since the time of the dinosaurs, always seeking the shortest and steepest route possible. Approximately once every 1000 years, the river jumps out of its banks and carves a new path. In John McPhee's fantastic essay, The Control of Nature, we learn:

The Mississippi's main channel of three thousand years ago is now the quiet water of Bayou Teche, which mimics the shape of the Mississippi. Along Bayou Teche, on the high ground of ancient natural levees, are Jeanerette, Breaux Bridge, Broussard, Olivier--arcuate strings of Cajun towns. Eight hundred years before the birth of Christ, the channel was captured from the east. It shifted abruptly and flowed in that direction for about a thousand years. In the second century a.d., it was captured again, and taken south, by the now unprepossessing Bayou Lafourche, which, by the year 1000, was losing its hegemony to the river's present course, through the region that would be known as Plaquemines. By the nineteen-fifties, the Mississippi River had advanced so far past New Orleans and out into the Gulf that it was about to shift again, and its offspring Atchafalaya was ready to receive it.

For the Mississippi to make such a change was completely natural, but in the interval since the last shift Europeans had settled beside the river, a nation had developed, and the nation could not afford nature. The consequences of the Atchafalaya's conquest of the Mississippi would include but not be limited to the demise of Baton Rouge and the virtual destruction of New Orleans. With its fresh water gone, its harbor a silt bar, its economy disconnected from inland commerce, New Orleans would turn into New Gomorrah. Moreover, there were so many big industries between the two cities that at night they made the river glow like a worm. As a result of settlement patterns, this reach of the Mississippi had long been known as "the German coast," and now, with B. F. Goodrich, E. I. du Pont, Union Carbide, Reynolds Metals, Shell, Mobil, Texaco, Exxon, Monsanto, Uniroyal, Georgia-Pacific, Hydrocarbon Industries, Vulcan Materials, Nalco Chemical, Freeport Chemical, Dow Chemical, Allied Chemical, Stauffer Chemical, Hooker Chemicals, Rubicon Chemicals, American Petrofina--with an infrastructural concentration equaled in few other places--it was often called "the American Ruhr." The industries were there because of the river. They had come for its navigational convenience and its fresh water. They would not, and could not, linger beside a tidal creek. For nature to take its course was simply unthinkable. The Sixth World War would do less damage to southern Louisiana. Nature, in this place, had become an enemy of the state.


The Atchafalaya steadily took more and more of the Mississippi's water to the Gulf of Mexico during the 20th Century, until by 1950, it had captured 30% of the great river's flow, becoming the 4th largest river in the U.S. by volume discharge. The Army Corps of Engineers stepped in, and in the late 1950s began construction of a massive structure that resembled a dam with gates to control the amount of water escaping from the Mississippi to the Atchafalaya. This "Low Sill Structure", completed in 1963, consisted of a dam with 11 gates, each 44 feet wide, that could be raised or lowered. The entire structure was 566 feet long. A companion "Overbank Structure" was built on dry land next to the Low Sill Structure, in order to control extreme water flows during major floods. The Overbank Structure had 73 bays, each 44 feet wide, and was 3,356 feet long. The total cost of the two structures: about $300 million.


Figure 2. Aerial view of the Mississippi River's Old River Control Structure, looking downstream (south.) Image credit: U.S. Army Corp of Engineers.

The flood of 1973: Old River Control Structure almost fails
For the first ten years after completion of the Old River Control Structure, no major floods tested it, leading the Army Corps to declare, "We harnessed it, straightened it, regularized it, shackled it." But in 1973, a series of heavy snowstorms in the Upper Midwest was followed by exceptionally heavy spring rains in the South. The Mighty Mississippi rose inexorably until the flow rate at the Old River Control Structure reached 2 million cubic feet per second--twenty times the flow of Niagara Falls--and stayed there for more almost three months. Turbulence from the unprecedented flows through the Low Sill Structure scoured the foundation and destroyed a 67-foot-high wing wall that guided water into the structure. Scour holes as big as a football field developed upstream, downstream, and underneath the structure, exposing 50 feet of the 90-foot long steel pilings supporting the structure. The structure began vibrating dangerously, so much so that it would slam open car doors of vehicles parking on top of Highway 15 that crosses over the top. Emergency repairs saved the structure, but it came every close to complete failure.

The flood of 1973 permanently damaged the Low Sill Structure, forcing the Corps to build additional structures to control future great floods. The first of these structures was the Auxilliary Control Structure. This 442-foot long structure, completed in 1986, consisted of six gates, each 62 feet wide, and cost $206 million to build. Joining the mix in the late 1980s was a 192-megawatt hydroelectric power plant, build at a cost of $520 million.


Figure 3. The flow of water in the Mississippi River as of Friday, May 13 (red line) has exceeded 2 million cubic feet per second, and was approaching the all-time record (dashed blue line.) Image credit: USACE.

The Old River Control Structure's greatest test: the flood of 2011
Flow rates of the Mississippi at the latitude of the Old River Control Structure are expected to exceed the all-time record on Saturday, giving the Old River Control Structure its greatest test since the flood of 1973. Since there are now four structures to control the flooding instead of just the two that existed in 1973, the Old River Control Structure should be able to handle a much greater flow of water. The flood of 2011 is not as large as the maximum 1-in-500 year "Project Flood" that the Old River Control Structure was designed to handle, and the Army Corps of Engineers has expressed confidence that the structure can handle the current flood. However, the system has never been tested in these conditions before. This is a dangerous flood, and very high water levels are expected for many weeks. Unexpected flaws in the design of the Old River Control Structure may give it a few percent chance of failure under these sorts of unprecedented conditions. While I expect that the Old River Control Structure will indeed hold back the great flood of 2011, we also need to be concerned about the levees on either side of the structure. The levees near Old River Control Structure range from 71 - 74 feet high, and the flood is expected to crest at 65.5 feet on May 22. This is, in theory, plenty of levee to handle such a flood, but levees subjected to long periods of pressure can and do fail sometimes, and the Corps has to be super-careful to keep all the levees under constant surveillance and quickly move to repair sand boils or piping problems that might develop. Any failure of a levee on the west bank of the Mississippi could allow the river to jump its banks permanently and carve a new path to the Gulf of Mexico. I'll say more about the potential costs of such an event in a future post.

According to the latest information from the Army Corps the Old River Control Structure is currently passing 624,000 cubic feet per second of water, which is 1% beyond what is intended in a maximum "Project Flood." The flow rate of the Mississippi at New Orleans is at 100% of the maximum Project Flood. These are dangerous flow rates, and makes it likely that the Army Corps will open the Morganza Spillway in the next few days to take pressure off of the Old River Control Structure and New Orleans levees. Neither can be allowed to fail. In theory, the Old River Control Structure can be operated at 140% of a Project Flood, since there are now four control structures instead of just the two that existed in 1973 (flows rates of 300,000 cfs, 350,000 cfs, 320,000 cfs, and 170,000 cfs can go through the Low Sill, Auxiliary, Overbank, and Hydroelectric structures, respectively.) Apparently, the Corps is considering this, as evidenced by their Scenario #3 images they posted yesterday. This is a risky proposition, as the Old River Control Structure would be pushed to its absolute limit in this scenario. It would seem a lower risk proposition to open the Morganza spillway to divert up to 600,000 cfs, unless there are concerns the Corps has they aren't telling us about.


Figure 4. Kayaking, anyone? The stilling basin downstream of the Low Sill Structure of the Old River Control Structure, as seen during major flood stage of the Mississippi River on May 10, 2011. The flow rate is 2 - 3 times that of Niagara Falls here. Video by Lee Alessi.

Recommended reading
John McPhee's fantastic essay, The Control of Nature

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 308 - 258

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17Blog Index

I am under a torrential thuunderstorm as I type this.Go to my blog and see the radar and flood advisories in Puerto Rico.

Link
Member Since: April 29, 2009 Posts: 75 Comments: 14900
306. beell
Quoting cat5hurricane:

NP. Then again, the 18Z (just out) paints an entirely different picture.


Same pieces. Cut off or closed mid level low slowly dragging a trailing frontal boundary. Pushing up the blocking ridge downstream.
Member Since: September 11, 2007 Posts: 145 Comments: 16921
News article on the proposal for an anthropocene...

The scientists note that getting that formal designation will likely be contentious. But they conclude, "However these debates will unfold, the Anthropocene represents a new phase in the history of both humankind and of the Earth, when natural forces and human forces became intertwined, so that the fate of one determines the fate of the other. Geologically, this is a remarkable episode in the history of this planet."


Thinking that Japan and Mississippi may be data points in the hypothesis.

Full article at
http://www.sciencedaily.com/releases/2010/03/1003 26101117.htm
Member Since: Posts: Comments:
303. beell
Quoting cat5hurricane:

Didn't want you to get lonely over there.


LOL. thx.
Member Since: September 11, 2007 Posts: 145 Comments: 16921
Speaking of old, where is Gother?
Member Since: Posts: Comments:
it is coming to that time of year, Epac season gets underway tomorrow 13th May
Member Since: Posts: Comments:
Round 4 coming up for the Philippines.



Member Since: September 30, 2007 Posts: 9 Comments: 15977
297. beell
Quoting cat5hurricane:

This aint gonna help matters, Pat rap for beautiful NOLAtown.



You're a believer now?
Member Since: September 11, 2007 Posts: 145 Comments: 16921
Quoting Neapolitan:

What, you're not even going to have the courtesy of properly attributing your comment to Jeff Dunetz over at BigGovernment.com?

I saw that piece earlier this afternoon, and responded in the forum. There are some real characters over there. Talk about "moonbats". ;-)

I'll go check it out. Moonbats give away great data for fiction characters for fantasy novels. I wonder what they think of the new "Anthropocene epoch". Ref post 366 yesterday's blog.
Member Since: Posts: Comments:
295. srada
Bad weather shaping up for us folks in SE NC today/tonight..also two low pressures also supposed to develop off NC/SC coast come Monday and Tuesday..

LATEST NAM IS A BIT DISCONCERTING FOR TONIGHTS FORECAST AS
THE ACTIVITY CURRENTLY MOVING ACROSS THE FLORIDA PANHANDLE VIA A MID
LEVEL VORT IS NOW SHUNTED OFF THE COAST. WILL WAIT FOR OTHER 1200
UTC GUIDANCE TO ADDRESS THIS KEEPING FOCUS ON THE EXTREME NEAR TERM.
Member Since: Posts: Comments:
jax82- don't know what area of the beach you're at, we're near ponte vedra. It's probably gonna go all north of us, airport's gonna get some good mess, tho.
Member Since: August 13, 2005 Posts: 178 Comments: 26654
WOW, only 8 comments in past hour...
I'm at work...so I can check in every now and then..but where is everyone this morning?

I guess out enjoying themself. If iwere not at work; I probably would not be here either!

Later!!!
Member Since: Posts: Comments:
Quoting aquak9:
good morning my friend gambler. Truly a day of history.

Wish the younger folks here would take advantage of this, and learn as much as they can. Remember it, carry this knowledge into their older years.


ayup

I think I represent the "old" part of that old crew remark.
Member Since: Posts: Comments:
Quoting Rbirds:
When reading Dr. Masters' quite excellent piece about controlling the Mississippi I thought of this piece of Southern humor on the subject:


Appreciating the fact that her [my mother-in-law's] life depended on being in a dry climate, I rented a house in the flood section of Louisiana, in a town called Swamp Haven. Swamp Haven is on the banks of the Mississippi river, when it's not under it….That landlord was actually imbued with the idea that Swamp Haven was the only town on the map…. I said [to him], "Don't you think it would have a tendency to check these floods if the citizens would get together to dam the water?" He said, "No, I think prayers would do more good than profanity"

William D. Hall, Diversified Drollery: A Monologue, Satirical and Reminiscent,, 2-4, 1904.


Southern humor.....just cant beat it...1904 at that, thanks for posting :)
Member Since: September 16, 2010 Posts: 0 Comments: 1496
sunny yet hazy here in Jax, but all 13 weather radios just went off.

I still have my doubts.
Member Since: August 13, 2005 Posts: 178 Comments: 26654
Quoting NOLA2005:
For anyone interested in watching, ACOE will livestream the opening of the Morganza. Last I heard this will happen sometime around or shortly after 2:30 pm CDT.
Here's the link:
Link



Thank you for that link :)...I will be watching...
Member Since: September 16, 2010 Posts: 0 Comments: 1496
For anyone interested in watching, ACOE will livestream the opening of the Morganza. Last I heard this will happen sometime around or shortly after 2:30 pm CDT.
Here's the link:
Link
Member Since: Posts: Comments:
When reading Dr. Masters' quite excellent piece about controlling the Mississippi I thought of this piece of Southern humor on the subject:


Appreciating the fact that her [my mother-in-law's] life depended on being in a dry climate, I rented a house in the flood section of Louisiana, in a town called Swamp Haven. Swamp Haven is on the banks of the Mississippi river, when it's not under it….That landlord was actually imbued with the idea that Swamp Haven was the only town on the map…. I said [to him], "Don't you think it would have a tendency to check these floods if the citizens would get together to dam the water?" He said, "No, I think prayers would do more good than profanity"

William D. Hall, Diversified Drollery: A Monologue, Satirical and Reminiscent,, 2-4, 1904.
Member Since: Posts: Comments:
Quoting Patrap:
Im bout 7 miles Upriver from there,,but the scene is quite uncomfortable to say the least,,

Im off to get some imagery and video.

Back this aft.

One Nola Roux in tow as well.


This is a pic I took about 5 river miles upriver from Pat. The Levee here is el.25.50 the River is el.17.10. The levees here are some of the highest levees around New Orleans.

Member Since: Posts: Comments:
Quoting PcolaDan:

Yea, don't think this one is for you. We were lucky this one made it this far south with moisture.


Well, like I said, at least somewhere in North Florida there will be rain..and hopefully some of it will run off to the south..

Our rainy season will come soon... I hope!
Member Since: Posts: Comments:
Quoting seflagamma:
But P'cola, they NEVER make it south of Lake O!

None of these fronts for past 6 months held together to make it thru SE Florida.

Yea, don't think this one is for you. We were lucky this one made it this far south with moisture.
Member Since: Posts: Comments:
We have a lot of "fushia" in SE Florida..(Broward and Palm Beach Counties).not good at all.




Member Since: Posts: Comments:
But P'cola, they NEVER make it south of Lake O!

None of these fronts for past 6 months held together to make it thru SE Florida.
Member Since: Posts: Comments:
Quoting PcolaDan:
Earth Observatory images
Morganza Floodway, 1973


Impresiv! Thank you for that picture.
Makes it for me - as an European - a bit easier to imagine the dimensions.

*returns to partial wintersleep until the season really lets loose*

Member Since: Posts: Comments:
Hang in there aqua, it's still holding together.

Member Since: Posts: Comments:
Good morning Aqua,
that is what I am afraid of! But at this point a TS or even easy mild Cat 1 would be worth it.


Actually Broward and Palm Beach counties, I'll bet we have not had 1" of rain for the past 3 months.. and probably not since first of year.. we are dark red and have been that way for months..

We just don't cover as large an area as Texas and have not had all the wild fires.. we have them but they are not as big...

Just thankful North and Central Fla have gotten some rainfall earlier this year...
Member Since: Posts: Comments:
hi gamma

texas in WAY worse shape than we ever dreamed of- and I haven't even seen a spit of rain since I don't know when

it will come, with a number or a name
Member Since: August 13, 2005 Posts: 178 Comments: 26654
Quoting aquak9:
I see slowly but surely the old crew is crawling out of their winter caves

Hey!! most of us aren't even using walkers yet!


Hi "old crew" LOL

All you North Fla folks bragging about your rain fall.. have mercy on us down here in SE Fla.

Last Dec - Feb you all were blue and green on the Fla Drought map while SE Fla was already red..
we have been red since the beginning of the year! While you all have had a few "green" days when you got some rain from these fronts!

But I must in fairness add, and some of my neighbors will kill me...
when the only rain Florida gets falls North of Lake Okeechobee, it makes our drought conditions better because your rain will eventually drain downward into the Lake and Everglades to raise our water tables.

A few years ago only South Fla got rain and North Fla was burning up..
our water did not flow upstream to help you all... it just got drained off into the ocean and helped no one.

now don't get me wrong, we are brittle dry and need a shower.. oh wait I forgot last week we got 0.15 " first rain we got in over a month!


Good morning my friends!
Member Since: Posts: Comments:
Earth Observatory images
Morganza Floodway, 1973
Member Since: Posts: Comments:
I can see rain clouds. could it be?
Member Since: Posts: Comments:
Im bout 7 miles Upriver from there,,but the scene is quite uncomfortable to say the least,,

Im off to get some imagery and video.

Back this aft.

One Nola Roux in tow as well.
Member Since: Posts: Comments:
Quoting Patrap:
About as much as one can be Uptown,,LoL

heya MS
As long as your out of the way of the flood, I'll pray for you on the rest....lol
Member Since: Posts: Comments:
gambler- here's a cam, I think it's near Pat.

Errr...not for the faint of heart.

Link
Member Since: August 13, 2005 Posts: 178 Comments: 26654
Quoting IKE:

For here...

Monday Night: Partly cloudy, with a low around 48.

Tuesday: A 20 percent chance of showers after 1pm. Mostly sunny, with a high near 76.

Tuesday Night: Partly cloudy, with a low around 49.


Yeah, NWS says we'll reach the low 60s in Naples on Tuesday, which would be the coolest it's been here in over a month. But we'll stay in the low 90s from Wednesday onward, so that'll be fine.
Member Since: November 8, 2009 Posts: 4 Comments: 13802
About as much as one can be Uptown,,LoL

heya MS
Member Since: Posts: Comments:
Yes, a start for the history books for sure. Pat, you are high out of harms way?
Member Since: Posts: Comments:
good morning my friend gambler. Truly a day of history.

Wish the younger folks here would take advantage of this, and learn as much as they can. Remember it, carry this knowledge into their older years.
Member Since: August 13, 2005 Posts: 178 Comments: 26654
Quoting hcubed:


And, according to the map in #131, I10 may be seeing some problems 24 hours after Morganza's opened.

Anyone know the height of I10 at that point? They may have to restrict traffic on all the bridges for a while.


I-10 is on continuous elevated bridge structure 30' above the normal basin tidal level from just east of Henderson to about 7 miles W of Grosse Tete, for a distance of around 25 miles.

And that doesn't include the height of the Whisky Bay and Atchafalaya River crossings, which are higher.

Considering that much width, there should be no problems on I-10 whatsoever, at least not the "Swamp Freeway" segments.


Anthony
Member Since: Posts: Comments:
Good morning the Beautiful water puppy, Wize and Stellar Pat, Awesome Mate Aussie, and who could forget the Radiant Atmo
Member Since: Posts: Comments:
I made a poll on my blog about when will Arlene form.If any of you wants to participate,go there.

Link
Member Since: April 29, 2009 Posts: 75 Comments: 14900
Tropical depression ONE May 28th-29th

I think we might get something like this soon.
14 hours till Epac hurricane season.

Epac Jun 2010

Who said June couldn't be busy?
Member Since: Posts: Comments:
Record Report

Statement as of 3:00 PM CDT on May 13, 2011

... Preliminary river reading record broken at Red River Landing...

This is preliminary data pending official record keeping by the U S
Army corp of engineers. Red River Landing as of 3 PM CDT has reached
a gage reading of 61.64 feet. This is greater than the crest of the
1997 river reading of 61.61 recorded on March 24th 1997. Again this
is preliminary.

Red River Landing however is not cresting and the official forecast
still calls for the Mississippi River to continue to rise with a
forecast crest of 65.5 feet on may 22nd.
Member Since: Posts: Comments:
Quoting Skyepony:
Here's someone in Terrebonne Parish, expected to get 5' of water in her house when Morganza spillway is opened. Bought & built there without ever knowing it was a flood plain.

Ow.
Member Since: Posts: Comments:

Viewing: 308 - 258

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Overcast
39 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron