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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Hmm, a little surprise to me... Monsoonal moisture started to flare for the first time this year in the Mountains and Deserts of Southern California today...

I think it's a little early though I haven't checked the history... Does this have any implications for the gulf and/or Mississippi Valley?
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BREAKING NEWS: The Mississippi River Commission has given U.S. Army Corp of Engineers the authority to open the Morganza Spillway in the next 24 hours, Louisiana Gov. Bobby Jindal said.

(Surprise!)
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Speaking of waters in the Gulf:

Sick fish in Gulf are alarming scientists: unusual number a 'huge red flag' to scientists, fishermen

Scientists are alarmed by the discovery of unusual numbers of fish in the Gulf of Mexico and inland waterways with skin lesions, fin rot, spots, liver blood clots and other health problems.

"It's a huge red flag," said Richard Snyder, director of the University of West Florida Center for Environmental Diagnostics and Bioremediation. "It seems abnormal, and anything we see out of the ordinary we'll try to investigate."

Are the illnesses related to the BP oil spill, the cold winter or something else? That's the big question Snyder's colleague, UWF biologist William Patterson III, and other scientists along the Gulf Coast are trying to answer. If the illnesses are related to the oil spill, it could be a warning sign of worse things to come.

In the years following the 1989 Exxon Valdez oil spill in Alaska's Prince William Sound, the herring fishery collapsed and has not recovered, according to an Exxon Valdez Oil Spill Trustee report. The herring showed similar signs of illness -- including skin lesions -- that are showing up in Gulf fish.

- - - - - - - - - -

[Scientists] say it's hard to determine just how many fish are being found sick because many commercial fishermen are reluctant to report their findings to state and federal officials out of fear fishing grounds will be closed and their livelihoods will be put at risk.

Article...
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Quoting BahaHurican:
Afternoon all...

Is this the latest forecast map?????



Just wanted to remind all that hurricane season starts in either 2 or 18 days, depending on ur basin.... LOL
Hurricane Freud seems familiar...hmmmm.
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Afternoon all...

Is this the latest forecast map?????



Just wanted to remind all that hurricane season starts in either 2 or 18 days, depending on ur basin.... LOL
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Quoting OrchidGrower:
Are any of the higher-ups considering helping the Mississippi return to one of its original benefits (to us!) of building land along the Gulf? My understanding is that, especially since all the flood-control measures, the River is forced to move at such a high speed, it is unable to dump its sediment load until it is much further out in the Gulf than where the soil would actually rebuild wetlands. Does anyone know if that's true? Certainly the silt load coming down the Mississippi this year will be astronomical.
little new wetland is built because the south and southwest passes (mouth of river) reach to the edge of the continental shelf causing the sediments to be deposited in very deep water.
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Are any of the higher-ups considering helping the Mississippi return to one of its original benefits (to us!) of building land along the Gulf? My understanding is that, especially since all the flood-control measures, the River is forced to move at such a high speed, it is unable to dump its sediment load until it is much further out in the Gulf than where the soil would actually rebuild wetlands. Does anyone know if that's true? Certainly the silt load coming down the Mississippi this year will be astronomical.
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BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE MEMPHIS TN
426 PM CDT FRI MAY 13 2011

THE NATIONAL WEATHER SERVICE IN MEMPHIS HAS ISSUED A

* TORNADO WARNING FOR...
SOUTHWESTERN CARROLL COUNTY IN NORTHWEST TENNESSEE...
EAST CENTRAL CROCKETT COUNTY IN NORTHWEST TENNESSEE...
SOUTHEASTERN GIBSON COUNTY IN NORTHWEST TENNESSEE...
NORTH CENTRAL MADISON COUNTY IN SOUTHWEST TENNESSEE...

* UNTIL 500 PM CDT

* AT 426 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM PRODUCING A TORNADO NEAR HUMBOLDT...MOVING EAST
AT 35 MPH.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO HUMBOLDT
AND MILAN.
Member Since: August 7, 2010 Posts: 0 Comments: 1933
Quoting HomoLibrarius:
the best oysters are from Apalachicola bay anyway.

The best oysters are mountain oysters.


Why am I not surprised by that assessment.

Island living perhaps?
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bad signs lowering pressures in Caribbean
Member Since: September 26, 2009 Posts: 2 Comments: 15670
Quoting SQUAWK:
Here is the part of this flood thing that I do not understand. They have been yakking about this flood for weeks. It is not like it is unexpected. Why were these flood control measures not opened last week and drop the level of the river before these huge swells came down river and lessen the impact on the whole system? Is that too simple and not doable?
If the river rises too fast, it can damage the levees. Also, there were lots of unknowns on just how high the river would get. Why divert 1.2 million cfs from the Mississippi, if you only need to divert 600k?
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Here is the part of this flood thing that I do not understand. They have been yakking about this flood for weeks. It is not like it is unexpected. Why were these flood control measures not opened last week and drop the level of the river before these huge swells came down river and lessen the impact on the whole system? Is that too simple and not doable?

It almost seems like they are playing "chicken" with the river. That seems like a bad idea to me.
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Quoting txjac:
If/when they open the floodgates will the flooding be worse then it was in the other states that opened flood gates? I'm not familiar with the layout of the land ...are we talking about ruining more crops and farmland? Or are these areas that will be flooded more of communities with housing?
Mostly farm and swampland, some communities, but nothing huge considering the size of the land to be flooded.
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If/when they open the floodgates will the flooding be worse then it was in the other states that opened flood gates? I'm not familiar with the layout of the land ...are we talking about ruining more crops and farmland? Or are these areas that will be flooded more of communities with housing?
Member Since: April 24, 2010 Posts: 1 Comments: 2511
Ike, got my fingers crossed for you ...I was in your seat yesterday and our rain pretty much fell apart
Member Since: April 24, 2010 Posts: 1 Comments: 2511
85. IKE
Come on rain...just a tad further east without dissipating and I'm in business....woohoo!


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Quoting Gearsts:
I hope that rain will soon move a little north we have a extreme drought this year
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Thanks for info Levi32,everyone have a blessed day.
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Quoting Neapolitan:
Just a brief interruption for a Fukushima update: as was mentioned earlier today and yesterday, TEPCO now admits that reactor #1 did indeed melt down, with the fuel burning a hole right through the pressure vessel. And based on radiation levels in the air and water, there's also a great chance that a similar situation is going on in reactors 2 and 3.

Because of this, leading nuclear experts now say that the only practical alternative will likely be to dig a trench around reactors 1-3 all the way down to the bedrock, which lies about 50 feet below ground level. This trench would first be filled with zeolite, which absorbs cesium. Next, the entire mess would be surrounded by a tsunami-proof concrete wall 100-feet high, then topped by a thick protective cover. If even one meltdown has happened, radiation levels would be so high that construction of this sarcophagus will likely take years, all while the reactors are belching extremely high levels of radiation.

This would, of course, also necessitate a Pripyat-like property buyout and creation of a no-admittance no-man's land covering many hundreds of square kilometers around the site.

In other Fukushima news: 1) the Fukushima prefectural government somehow failed to issue warnings to four of the six towns surrounding the Fukushima following the accident. 2) Highly radioactive ashes were detected in incinerator ashes at a sewage plant in Tokyo a few days after the accident. No word on how the radioactive substances got there, nor, more importantly, how many Japanese citizens were unknowingly irradiated by this fallout.

Nuclear power: the gift that keeps on giving. And giving. And giving. And giving...

Okay, sorry for the momentary digression. Back to the high-priority news: did you hear that Ashton Kutcher is taking Charlie Sheen's place on Two And A Half Men?


And in other news, a 3-headed glow-in-the-dark calf was found wandering a pasture 30 miles from the striken power plant. Investigators were further stunned when the calf asked, in perfect Japanese, where the nearest milk factory was, and the best way to travel there.
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Neo you are too, too funny with your last comment. I also have been reading about the NP situation in Japan. Scary stuff
Member Since: April 24, 2010 Posts: 1 Comments: 2511
Just a brief interruption for a Fukushima update: as was mentioned earlier today and yesterday, TEPCO now admits that reactor #1 did indeed melt down, with the fuel burning a hole right through the pressure vessel. And based on radiation levels in the air and water, there's also a great chance that a similar situation is going on in reactors 2 and 3.

Because of this, leading nuclear experts now say that the only practical alternative will likely be to dig a trench around reactors 1-3 all the way down to the bedrock, which lies about 50 feet below ground level. This trench would first be filled with zeolite, which absorbs cesium. Next, the entire mess would be surrounded by a tsunami-proof concrete wall 100-feet high, then topped by a thick protective cover. If even one meltdown has happened, radiation levels would be so high that construction of this sarcophagus will likely take years, all while the reactors are belching extremely high levels of radiation.

This would, of course, also necessitate a Pripyat-like property buyout and creation of a no-admittance no-man's land covering many hundreds of square kilometers around the site.

In other Fukushima news: 1) the Fukushima prefectural government somehow failed to issue warnings to four of the six towns surrounding the Fukushima following the accident. 2) Highly radioactive ashes were detected in incinerator ashes at a sewage plant in Tokyo a few days after the accident. No word on how the radioactive substances got there, nor, more importantly, how many Japanese citizens were unknowingly irradiated by this fallout.

Nuclear power: the gift that keeps on giving. And giving. And giving. And giving...

Okay, sorry for the momentary digression. Back to the high-priority news: did you hear that Ashton Kutcher is taking Charlie Sheen's place on Two And A Half Men?
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Member Since: August 2, 2010 Posts: 0 Comments: 1741
MODIS True Color images for 05/12/2011
Click any thumbnail for a full-resolution image


Atchafalaya Bay
Aqua-1 11/05/12 1900 UTC
Member Since: July 3, 2005 Posts: 423 Comments: 128240
One can see the expanding Fresh Water Plume in the Sw Lake from the Bonnet Carre on the MODIS Image

Member Since: July 3, 2005 Posts: 423 Comments: 128240
Quoting SQUAWK:


Short-term ... Pat is gonna spend more for his po' boy.
Don't worry Pat, the best oysters are from Apalachicola bay anyway.
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Quoting Patrap:
TP's Bob Marshall explains the good, bad and ugly for oysters

Posted on Thursday, May 12, 2011 4:42PM
The Times-Picayune's Outdoors editor Bob Marshall explains what it means for oysters with the opening of the Bonnet Carre spillway and the introduction of vast amounts of fresh water into Lakes Pontchartrain and Borgne and the marshes east of the Mississippi River.


Short-term ... Pat is gonna spend more for his po' boy.
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tropical troubles come soon oooh boyyy
Member Since: September 26, 2009 Posts: 2 Comments: 15670
Quoting mossyhead:
If you would look at it further, look at the time it would take to plan it, get the enviromental impact studies,taking over the land, and build the dams and water control. Businesses would have to relocate to offset the major problems. And the fresh water problems for N.O. and Baton Rouge would cause problems for industry as well as civilian.


Transform the ORCS into the Old River Canal Structure? This would complete the connection and then the "old river" channel is added to the Intracoastal Waterways along the Atlantic and Gulf Coasts. Seems like a logical fix to me.

There has to be some kind of COE plan that exists just in case the river changing deltas actually happens, right?
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Quoting jeffs713:

IMO, if they can figure out a way to do it... Let the bottom half of the water column go down the Atchafalaya River (plus any floodwaters), and *divert* enough water to keep the Mississippi a navigable river from the top half of the water column. That way, the Mississippi will continue to be a major artery, but the sediment can still be used to restore the delta.


I think there is already some question whether the sediment load in the Mississippi is suffcient enough for delta/marsh building to keep up with what is lost to impoundment (lakes), coastal subsidence, and gosh-forbid, sea level rise. Maybe a topic for another blog?
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Quoting Inyo:
RE: End of May projections... New England does not need more rain, leave Vermont alone please. Scattered thunderstorms are OK but what we have been getting we do not want or need. Send it to Texas.


Hey, we in South East Florida are in really bad shape also! at this point, as bad as Texas!

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TP's Bob Marshall explains the good, bad and ugly for oysters

Posted on Thursday, May 12, 2011 4:42PM
The Times-Picayune's Outdoors editor Bob Marshall explains what it means for oysters with the opening of the Bonnet Carre spillway and the introduction of vast amounts of fresh water into Lakes Pontchartrain and Borgne and the marshes east of the Mississippi River.
Member Since: July 3, 2005 Posts: 423 Comments: 128240
WOW, Dr Jeff, that was a very interesting article to read. Thank you for the information.

Makes you shutter to image what Mother Nature could do with that Mighty Mississippi that we have tried to "tame".

If it cuts a new path every 1000 years, I doubt man can stop it entirely.


Hello everyone,

What a nightmare unfolding here. I hope it is not as bad as some fear...


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Quoting beell:


Look at those same obstacles to relocate the entire petrochemical corridor that runs from New Orleans to Baton Rouge over to the "New Port of Morgan City". It might be possible to engineer river control that would offer a compromise and allow the lower end of the Mississippi River to carry on as always.

The dam would be faster and cheaper-opinion of course.

Some folks might be happy to see that industry go elsewhere. Overseas, perhaps?


IMO, if they can figure out a way to do it... Let the bottom half of the water column go down the Atchafalaya River (plus any floodwaters), and *divert* enough water to keep the Mississippi a navigable river from the top half of the water column. That way, the Mississippi will continue to be a major artery, but the sediment can still be used to restore the delta.
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65. 7544
Quoting Levi32:
One can see here that the 200mb equatorial ridge is still sitting way down near the equator (look for it northeast of Brazil). That ridge is forecasted by the GFS to make a significant shift northward to between 10N and 15N during the final 10 days of May, which will provide a lower wind-shear environment in the Caribbean, at least periodically, which could support tropical mischief should a disturbance develop.


thanks levi and this shows it also in may
Link
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This is a very interesting Blog,Thank you Mr. Masters,

First from the point of view that it is a man made disaster that is needing to be avoided. The river would probably by now have changed its course in the 1973 event if it had not been 'prevented,' and this is the quandary that is now being posed.
I as an engineer have a bit of experience of flatland rivers that move generally slowly and one thing that happens when they are in flood is that they can get a lot of side bank eddies, which eat up the river bank/levy from the direction of the sea backwards, they are very unpredictable and can very rapidly eat out the surrounding land then the river changes course very rapidly if this happens:-
The old course of the river still initially has flow but the flow is slow and carries a lot of what is called 'bed load,' this rapidly chokes up the old river bed to the point where it almost fills it. this would probably eliminate the easy possibility of using the old river bed as sort of a canal with locks at the ends,{in itself a massive project,} The new course of the river rapidly cuts a new lower bed than the old course,which in turn also initially contains lots of rapids.These are eaten away and smoothed rapidly normally.
The problem with this kind of flood is that a large mass of steady flowing water is more or less harmless until it speeds up, I would be and I am paying a lot of attention to bends and reverse flow eddies from now on.You are going to need a lot of luck and some very good 40 year old engineering structures to stand this one.
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This is for DestinJeff.
Member Since: July 8, 2005 Posts: 259 Comments: 24016
Quoting mossyhead:
If you would look at it further, look at the time it would take to plan it, get the enviromental impact studies,taking over the land, and build the dams and water control. Businesses would have to relocate to offset the major problems. And the fresh water problems for N.O. and Baton Rouge would cause problems for industry as well as civilian.


Look at those same obstacles to relocate the entire petrochemical corridor that runs from New Orleans to Baton Rouge over to the "New Port of Morgan City". It might be possible to engineer river control that would offer a compromise and allow the lower end of the Mississippi River to carry on as always.

The dam would be faster and cheaper-opinion of course.

Some folks might be happy to see that industry go elsewhere. Overseas, perhaps?

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Terrific entry. I became fascinated with the Old River Control Structure some years ago. Contextualizing it for readers as "America's Achilles' heel" is brilliant, and could not be more true.

One note on the name: "Old" does not mean that the structure is an old one; rather, it refers to the short waterway connecting the Mississippi to the Atchafalaya, which became known in the mid-1800s as "Old River."

Here are a couple links with some great info on ORCS, and also an interesting summary of the Army Corps' general plan for controlling river flooding from ORCS down past New Orleans, which utilizes: 1) Bonnet Carré, 2) Morganza, then, if all else fails 3) the Fuse Plug levee (a self-activating levee that is designed to destroy itself and allow water to go further west if Morganza Floodway fills!):



http://www.americaswetlandresources.com/backgroun d_facts/detailedstory/LouisianaRiverControl.html



http://www.wetmaap.org/False_River/Suppliment/fr_ background.html#The%20Great%20Raft:%20Brief%20Chro nology
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Quoting Patrap:
RIVERCAM: Angry Algiers point New Orleans seen from East bank near Jackson Square
it it panned to the right I'd almost be able to see my old house.
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Quoting Levi32:
One can see here that the 200mb equatorial ridge is still sitting way down near the equator (look for it northeast of Brazil). That ridge is forecasted by the GFS to make a significant shift northward to between 10N and 15N during the final 10 days of May, which will provide a lower wind-shear environment in the Caribbean, at least periodically, which could support tropical mischief should a disturbance develop.



"Tropical Mischief" Counter = "Tropical Mischief" Counter + 1. ;-)

Thanks for the info Levi.
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RIVERCAM: Angry Algiers point New Orleans seen from East bank near Jackson Square
Member Since: July 3, 2005 Posts: 423 Comments: 128240

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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.