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

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

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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

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408. msgambler
8:42 PM GMT on May 14, 2011
Your to kind Ally. Us Bama folk gotta stick together
Member Since: February 27, 2010 Posts: 0 Comments: 1125
407. AllyBama
8:42 PM GMT on May 14, 2011
Quoting emcf30:
scouring

Removal of soil or fill material by the flow of floodwaters. The term is frequently used to describe storm-induced, localized conical erosion around pilings and other foundation supports where the obstruction of flow increases turbulence. See Erosion.

www.csc.noaa.gov/rvat/glossary.html


thank you...now I feel so smart - lol
Member Since: August 3, 2006 Posts: 133 Comments: 20639
406. Patrap
8:41 PM GMT on May 14, 2011
lol..

no video ,,well dat just bites
Member Since: July 3, 2005 Posts: 427 Comments: 129444
405. AllyBama
8:41 PM GMT on May 14, 2011
gambles - thanks!...and even if it is wrong (which I doubt) - sounds great to me!..lol
Member Since: August 3, 2006 Posts: 133 Comments: 20639
404. emcf30
8:40 PM GMT on May 14, 2011
scouring

Removal of soil or fill material by the flow of floodwaters. The term is frequently used to describe storm-induced, localized conical erosion around pilings and other foundation supports where the obstruction of flow increases turbulence. See Erosion.

www.csc.noaa.gov/rvat/glossary.html
Member Since: August 7, 2010 Posts: 0 Comments: 1957
403. msgambler
8:40 PM GMT on May 14, 2011
Sorry to hear about arm Pat, I told you to quit mouthing of to her.
Member Since: February 27, 2010 Posts: 0 Comments: 1125
402. msgambler
8:38 PM GMT on May 14, 2011
Quoting AllyBama:
entropy101 - thanks for the info..I can understand - now just need to go look up "scouring"..lol
Quoting AllyBama:
entropy101 - thanks for the info..I can understand - now just need to go look up "scouring"..lol
It's what a tornado does to land, water does to concrete at high travel rates, what wind does to trees in a hurricane.....I think!!!! Not the sharpest knife in the drawer here.
Member Since: February 27, 2010 Posts: 0 Comments: 1125
401. Patrap
8:38 PM GMT on May 14, 2011
kitchen closed ms,,right arm in sling.
cool,,was 13 last time they opened morganza,I-10 was`still new.
Member Since: July 3, 2005 Posts: 427 Comments: 129444
confound it- I can't get chik's feed or the other one

grrrr
Member Since: August 13, 2005 Posts: 175 Comments: 26506
entropy101 - thanks for the info..I can understand - now just need to go look up "scouring"..lol
Member Since: August 3, 2006 Posts: 133 Comments: 20639
Quoting entropy101:
If they designed the spillway correctly: No.

The biggest issue is scouring at the backside of the spillway. If I understood right, they opened the door that had the best scouring protection behind it. So if that one holds and the water rises, they open the next one. Because at that point the difference in water height is less than with the first door, the scouring should theoretically be less.


That what they said during the press conference prior to the opening of the gate
Member Since: August 7, 2010 Posts: 0 Comments: 1957
Quoting Patrap:
Im no engineer,,more a sous Chef,cher
Ohh, can I place my order then?
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Yes it does
Quoting Tazmanian:
dont the Mississippi River go in too the gulf of mx at some point in time?

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Im no engineer,,more a sous Chef,cher
Member Since: July 3, 2005 Posts: 427 Comments: 129444
ok, I got feed again...work internet not the best...but I HAD to be a witness to this.
Member Since: August 13, 2005 Posts: 175 Comments: 26506

Quoting Tazmanian:
dont the Mississippi River go in too the gulf of mx at some point in time?

Member Since: Posts: Comments:
NP, but I do not know the answer. For that we will have to rely on the all popular, most loved, Patrap.
Member Since: February 27, 2010 Posts: 0 Comments: 1125
Quoting AllyBama:
Stupid question of the day:

until they open up another bay, won't this put too much pressure on bay #1 which could create other issues?
If they designed the spillway correctly: No.

The biggest issue is scouring at the backside of the spillway. If I understood right, they opened the door that had the best scouring protection behind it. So if that one holds and the water rises, they open the next one. Because at that point the difference in water height is less than with the first door, the scouring should theoretically be less.
Member Since: May 13, 2011 Posts: 0 Comments: 4
dont the Mississippi River go in too the gulf of mx at some point in time?
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Quoting msgambler:
Now Ally, you know that the only stupid question is the one not asked......lol


lol..thanks for the reassurance gambler!
Member Since: August 3, 2006 Posts: 133 Comments: 20639

Saturday marked the first time in history that all three floodways built by corps after 1927 flood -- the Morganza Floodway, the Bonnet Carre Spillway and the Birds Point floodway in Missouri -- have been in operation at the same time, according to the corps.




Morganza Floodway opens to divert Mississippi River away from Baton Rouge, New Orleans
Published: Saturday, May 14, 2011, 3:00 PM Updated: Saturday, May 14, 2011, 3:19 PM
Member Since: July 3, 2005 Posts: 427 Comments: 129444
Now Ally, you know that the only stupid question is the one not asked......lol
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from helicopter

Link
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Stupid question of the day:

until they open up another bay, won't this put too much pressure on bay #1 which could create other issues?
Member Since: August 3, 2006 Posts: 133 Comments: 20639
Man that is CRAZY how fast that area filled up with just only 1 bay open........
Member Since: August 7, 2010 Posts: 0 Comments: 1957
streaming here aquak9
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Quoting aquak9:
anyone else lose the live feed?

Yup, but it came back.
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Quoting aquak9:
anyone else lose the live feed?


This one's good.
WAFBCH9
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Today's Word Logic 'Winna'


"One of the big issues that we're facing is motor vessles, barges in particular, we need to keep them off the levees," Susan Macclay of the West Bank levee authority said Thursday during a news conference.
Member Since: July 3, 2005 Posts: 427 Comments: 129444
anyone else lose the live feed?
Member Since: August 13, 2005 Posts: 175 Comments: 26506
"Cajun Rodeo Rogue Barge Round-Up",,


Tugboats, UP!!!




Member Since: July 3, 2005 Posts: 427 Comments: 129444
I keep humming an old song, "The mighty Mississippi is the father of the waters." It goes on to something about "his sons and daughters," but I can't remember the rest of the words, and couldn't find it on Google. Anyone else know that one?
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Quoting aquak9:
told ya'll I was worried about them barges...

I hear ya
Member Since: August 7, 2010 Posts: 0 Comments: 1957
told ya'll I was worried about them barges...
Member Since: August 13, 2005 Posts: 175 Comments: 26506
Live link to Morganza.Link
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There she goes, First bay opening
Member Since: August 7, 2010 Posts: 0 Comments: 1957
Opening of Morganza has begun.
Member Since: July 3, 2005 Posts: 427 Comments: 129444
I guess they are going to be opening up that floodgate any time now.

I hope it is not too bad on those people and their homes.
Member Since: August 29, 2005 Posts: 301 Comments: 40945
Neither the national news networks nor TWC covering the Morganza Spillway opening.
There we go, headline news at 4 p.m.
Here's live feed from WAFB

Link

I would not want to be standing over that bay.
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Mississippi River floodgate to open at 3 p.m. CDT
By MARY FOSTER and MELINDA DESLATTE Associated Press 2011 The Associated Press
May 14, 2011, 2:35PM


MORGANZA, La. %u2014 Engineers made final preparations Saturday afternoon to slowly open a 10-ton, steel emergency floodgate for the first time in nearly four decades, purposefully inundating farmlands and homes in Louisiana's Cajun country to drain the swelling Mississippi River.


http://www.chron.com/disp/story.mpl/ap/nation/756 4902.html
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Two barges strike Mississippi River bridge in Baton Rouge
Published: Saturday, May 14, 2011, 2:16 PM


A pair of barges loose on the Mississippi River in Baton Rouge have struck the U.S. 190 bridge, forcing the bridge to close as a precaution, according to WAFB.

Authorities say 25 barges that had dislodged along the river in and near the capital city -- all of them north of the bridge -- have been contained and don't threaten levees, the station reports.

Meanwhile, the Louisiana Department of Transportation and Development is inspecting the U.S. 190 bridge, which is named for former Louisiana Gov. Huey P. Long. The structure is not the same Huey P. Long Bridge that crosses the Mississippi in Jefferson Parish.

The U.S. Coast Guard also has dispatched a team to inspect the bridge. It is not clear when the bridge will reopen.

Officials keeping watch over New Orleans levees have not reported any errant vessels on the river, though the matter is a top priority.

"One of the big issues that we're facing is motor vessles, barges in particular, we need to keep them off the levees," Susan Macclay of the West Bank levee authority said Thursday during a news conference.

All vessels are supposed to stay 180 feet away from the slope pavement, she said.

City Councilwoman Jackie Clarkson on Thursday barge owners and operators who don't moor their vessels that the city will sink all untethered vesselsA pair of barges loose on the Mississippi River in Baton Rouge have struck the U.S. 190 bridge, forcing the bridge to close as a precaution, according to WAFB.

Authorities say 25 barges that had dislodged along the river in and near the capital city -- all of them north of the bridge -- have been contained and don't threaten levees, the station reports.

Meanwhile, the Louisiana Department of Transportation and Development is inspecting the U.S. 190 bridge, which is named for former Louisiana Gov. Huey P. Long. The structure is not the same Huey P. Long Bridge that crosses the Mississippi in Jefferson Parish.

The U.S. Coast Guard also has dispatched a team to inspect the bridge. It is not clear when the bridge will reopen.

Officials keeping watch over New Orleans levees have not reported any errant vessels on the river, though the matter is a top priority.

"One of the big issues that we're facing is motor vessles, barges in particular, we need to keep them off the levees," Susan Macclay of the West Bank levee authority said Thursday during a news conference.

All vessels are supposed to stay 180 feet away from the slope pavement, she said.

City Councilwoman Jackie Clarkson on Thursday barge owners and operators who don't moor their vessels that the city will sink all untethered vessles.

"We can't afford to have barges breaking loose, breaking levees," she said. .

"We can't afford to have barges breaking loose, breaking levees," she said.
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Thanks Beell, makes more sense
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363. beell
Quoting msgambler:
Which bridge did they hit? Not the HPL, that is many miles from Baton Rouge


The old bridge. US 190. Going into the N side of Baton Rouge.

Popular name for a bridge in LA.
Member Since: September 11, 2007 Posts: 145 Comments: 16919
Apparently UStream has problems/isn't doing press conference.

WWLTV
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Which bridge did they hit? Not the HPL, that is many miles from Baton Rouge
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Thanks beell, I was on the Morganza chat and someone posted that.
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359. beell
Had not heard that until now, emcf30.

Barges get loose on river, two hit bridge
Posted: May 14, 2011 1:36 PM CDT
Updated: May 14, 2011 2:04 PM CDT
By Joshua Auzenne, Web Staff - email

BATON ROUGE, LA (WAFB) - Authorities said 25 barges dislodged in Baton Rouge north of the Huey P. Long Bridge (old bridge) Saturday afternoon.

Officials said two of the barges hit the bridge. The bridge has been closed in both directions as a precaution. Officials added all 25 barges have been contained and no longer pose a threat. The Louisiana Department of Transportation and Development is inspecting the bridge to find out if it has been damaged. The US Coast Guard is sending a team to the site to inspect the bridge as well. It is unknown when the bridge will be re-opened.
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Morganza on ustream will go live at 2:30 Link

Sorry, did not realize shoreacres already posted link
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.