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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sigh...ok, maybe I'd best start craving crawfish instead. Or are they gonna get wiped out from the flood?
Member Since: August 13, 2005 Posts: 163 Comments: 25704
Oh yes, Carp are eaten by many...in some parts of Ms they are called buffalo carp. My grandpa always said, when there were no more fish to be eaten, then you'd have buffalo carp, gar, or the lowly scavenger mud-cat. I personally have never eaten any of these, but grandpa did. I can remember him saying, the more ya chew carp, the bigger it gets, kinda like cotton in your mouth......now Aqua, are ya still hungry for some fish??? LOL..
Member Since: September 16, 2010 Posts: 0 Comments: 1492
gamma- that photo of the jumping carp is from the Morganza spillway today!

Rainman- I will NOT eat the fish out of the pond. You're just using that as an excuse to buy a motorboat.
Member Since: August 13, 2005 Posts: 163 Comments: 25704
Quoting seflagamma:
rolf, Aqua, my Dad tells me a lot of folks eat carp.. but we don't they are really bony.

#497 that is a great photo of a jumping carp!

Our local canals lost all our carp last winter to the cold temps....I guess we had tropical carp.. that were all put in our canals to eat grasses that are not suppose to grow here but do....nananananan whatever....
Someone had that bright idea for our pond out back, killed off practically everything else in it.
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Quoting goosegirl1:


My dad used to say carp taste like what they eat. Of course, this led to a young child asking "what do they eat?" His answer was "mud", but in retrospect... I'm sure that wasn't really what he meant ;)


I have never eaten carp but would be willing to try it. I am told that part of the problem is the way that North Americans are used to preparing fish is not appropriate for carp. Eastern Europeans tend to use it in hearty soups mixes where it is cooked long enough that the small bones break down and can be eaten. Asians have special ways of fixing it and I am told that there are those in the African-American community that have family recipes are likely based on practices from their land of origin. Googled carp recipes and they are myriad. The main concern with carp is that they are a long lived bottom feeder which will also opportunistically eat smaller fish. Therefore they tend to bioaccumulate any toxins in the stream. Therefore point of origin is very important. (may indeed affect flavor)
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Quoting ShenValleyFlyFish:


Despised by others ;)

That is Freekin Awesome B^)

Oh Hon, we need a couple of motor boats and some nets for the pond out back
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501. xcool
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rolf, Aqua, my Dad tells me a lot of folks eat carp.. but we don't they are really bony.

#497 that is a great photo of a jumping carp!

Our local canals lost all our carp last winter to the cold temps....I guess we had tropical carp.. that were all put in our canals to eat grasses that are not suppose to grow here but do....nananananan whatever....
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A decent disturbance in the African Easterly Jet is currently along ~4W, but likely not well-enough defined to be analyzed as a tropical wave by the NHC.

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Quoting ShenValleyFlyFish:


Despised by others ;)



Kind of like mullet. Despised by most, but a staple here. Difference is the bottom upon which they feed (mullet I mean), sandy here.
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from post 469, the link had a lotta pics

Member Since: August 13, 2005 Posts: 163 Comments: 25704
Quoting FirstCoastMan:
hey levi32...Does any of the models show anything forming towards the end of may?


Nothing consistent or significant yet.
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Quoting ShenValleyFlyFish:
I've been told the best way to fix carp is to bake it on an oak board, then throw out the carp and eat the board.


My dad used to say carp taste like what they eat. Of course, this led to a young child asking "what do they eat?" His answer was "mud", but in retrospect... I'm sure that wasn't really what he meant ;)
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Quoting aquak9:
they just looked so huge and lively in the pics, coming thru the spillway


where are the pics of the carp?
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Quoting Chicklit:

They are boney but eaten by some cultures.
Here's the scoop: Cyprinus carpio
Link


Despised by others ;)

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now I am hungry for seafood. Water water everywhere, and nary a fishie to eat.
Member Since: August 13, 2005 Posts: 163 Comments: 25704
Quoting txjac:
Pat, quick question please ...
Why does Houma not show to flood but all around it does? Is Houma at a higher sea level?
As Pat seems to not be on, atm...

Houma is protected by levees, and a recently improved one, IIRC. (But I cannot seem to find a map of them to share.)
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Quoting aquak9:
Are carp edible?


You be the judge.
(from Wikipedia)

Carp meat:
is rich in zinc, which boosts the immune system and slows the aging process;[citation needed]
accelerates the healing of wounds, is involved in bone formation;[citation needed]
contains a lot of sulfur that is indispensable to cartilage, skin, hair, nails, assimilation of nutrients;[citation needed]
clear the body of chemical waste;[citation needed]
has a beneficial effect on the digestive and nervous systems;[citation needed]
supports the body's oxygen balance necessary for normal brain function;[citation needed]
prevents the development and exacerbation of arthritis;[citation needed]
regulates blood sugar.[citation needed
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They are boney but eaten by some cultures.
Here's the scoop: Cyprinus carpio
Link
Member Since: July 11, 2006 Posts: 14 Comments: 11143
hey levi32...Does any of the models show anything forming towards the end of may?
Member Since: August 7, 2009 Posts: 0 Comments: 251
they just looked so huge and lively in the pics, coming thru the spillway
Member Since: August 13, 2005 Posts: 163 Comments: 25704
More wikipedia:

Although initially the carp was an important aquatic food item, as more fish species have become readily available for the table, the importance of carp culture in Western Europe has become less important because of declining demand, partly due to the appearance of more desirable table fish such as trout and salmon through intensive farming, and environmental constraints. However, fish production in ponds is still a major form of aquaculture in Central/Eastern Europe, including the Russian Federation where most of the production comes from low intensity or semi-intensive ponds. In Asia, the farming of carp continues to surpass the total amount of farmed fish volume of intensively sea-farmed species such as salmon and tuna.
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Yes, carp are edible. I've seen them in certain grocery stores. Wikipedia:

Various species of carp have been domesticated and reared as food fish across Europe and Asia for thousands of years.
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Quoting aquak9:
Are carp edible?
I've been told the best way to fix carp is to bake it on an oak board, then throw out the carp and eat the board.
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Quoting aquak9:
Are carp edible?


Aren't they a sport fish? I think they may put up a really good fight but not sure.
Yes, Baha, they are staggering the flow openings to give wildlife and people an opportunity to get out of the way, although one wonders where they will go!
Waking up at 4:30 or 5 a.m. these days so off to get some rest.
Member Since: July 11, 2006 Posts: 14 Comments: 11143
Quoting aquak9:
Are carp edible?


LOL, Aqua, I've never eaten one and I'm from Arkansas....

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Are carp edible?
Member Since: August 13, 2005 Posts: 163 Comments: 25704
Seems the plan to open a few gates at a time at Morganza makes a lot of sense. It means the flooding happens slower, which to my mind suggests that the impact of the water flow as it moves over the flood plain is likely to be less damaging. Also the slower flood rate gives people / animals more time to get away, I'd think.

It may sound a bit callous, but it's a good thing there IS an alternative in the first place. However, I'm sure that doesn't assauge the feelings of those who get flooded.....

Also watching the increased activity across the SE US and CAR with interest. It seems so quiet in the tropical ATL so far.... I keep wondering if it's the "calm before the storm".... lol
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Evening, folks. Finally some rain fell in Central Florida today. Now it's 68 degrees. The AP press release this afternoon said they would open one gate today and two tomorrow.



DailyMailOnlineLink
Member Since: July 11, 2006 Posts: 14 Comments: 11143
Quoting BahaHurican:
Evening all.

I'm watching that line of weather coming through S FL with interest.



While there's no rain in our forecast for tonight, I think that line looks likely to hold together until it gets to Nassau, eh?
'


We are getting rain in Broward County!!

After almost 6 months with very little rainfall and in severe drought for over 4 months..

We are getting rain..

My house has received over 1 1/2" in the past 2 hrs!!!

my pool is almost overflowing and the streets are flooded...but our canals can take the "drain off" tonight.


This is so good..and we have 40-50% chance of rain the next 5 days... this should "catch us up" if we really get rain the next 5 days.



Hi everyone, been watching the flooding situation....

so sad so many will be harmed but understood.


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477. txjac
Pat, quick question please ...
Why does Houma not show to flood but all around it does? Is Houma at a higher sea level?
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Quoting Tropicsweatherpr:
Yeah Levi,a very active day unfolded today in Puerto Rico that included Hail and a small tornado.See my blog about that.Looks like more rain on tap?

Has the upper high located NE of Brazil moved?


Oh wow, that's crazy.

Regarding the upper high, based on my animation in #472, it doesn't appear to have really moved yet. It will move north once the upper troughs lift out of the Caribbean area, which won't be for several days yet.
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Yeah Levi,a very active day unfolded today in Puerto Rico that included Hail and a small tornado.See my blog about that.Looks like more rain on tap?

Has the upper high located NE of Brazil moved?

Link
Member Since: April 29, 2009 Posts: 75 Comments: 13931
Evening all.

I'm watching that line of weather coming through S FL with interest.



While there's no rain in our forecast for tonight, I think that line looks likely to hold together until it gets to Nassau, eh?
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473. Skyepony (Mod)
Crew finds body of man stuck in snow for months... In OR, been in the woods about a week. Got buried with his tuck on Feb 14, lived til April 15th..lack of food.

The husband of the couple that got stuck out there too hasn't been found.
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Quoting CybrTeddy:
Interesting solutions from the NOGAPS and CMC now, possibly associated with the area of disturbed weather just south of Puerto Rico. Both take a disturbance from the Eastern Caribbean north of Puerto Rico and begin developing it once it passes north of Puerto Rico. I'd like to see consistency and the ECMWF and GFS get on with them before I seriously consider this as our possible first tropical mischief of the season - but its interesting to see.


Interesting. Although pressures will continue to be impressively low in the Caribbean and SW Atlantic, the models don't seem to show any real break in the subtropical jet screaming right across that area, which makes me doubt what the CMC and NOGAPS are saying. We shall see. For now, the pattern supports a lot of wetness for the lesser Antilles and Puerto Rico.

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471. Skyepony (Mod)
Situation Update No. 8
On 11.05.2011 at 16:27 GMT+2

The weather bureau has reported that tropical storm “Bebeng” (AERE) is out of the Philippine area of responsibility yesterday, but left 24 persons dead and more than P200-million worth of damage. The National Disaster Risk Reduction and Management Council (NDRRMC) yesterday said Albay and Camarines Sur have been placed under a state of calamity due to heavy damage caused by the storm.
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Interesting solutions from the NOGAPS and CMC now, possibly associated with the area of disturbed weather just south of Puerto Rico. Both take a disturbance from the Eastern Caribbean north of Puerto Rico and begin developing it once it passes north of Puerto Rico. I'd like to see consistency and the ECMWF and GFS get on with them before I seriously consider this as our possible first tropical mischief of the season - but its interesting to see.
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Hopefully, the National Guard is carefully watching the Mississippi upstream from and near the Old River Control structure & Morganza Spillway.

All we would need is an "Allahu Akhbar" BOOM! That would be bad news. They should have boats, including a tug boat in the water and ready to move out upstream of the Morganza and Old River Control. Anything floating downstream including loose barges, unidentified boats, etc... that even looks suspicious needs to be checked out.

I'm not trying to brighten anyone's day... just saying.
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CMC and ngp show something south of PRLink
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Alabama tornado victims begin moving into FEMA trailers
Published: Saturday, May 14, 2011, 5:00 PM



Jim Hannon, The Times Daily, via The Associated PressCharles Crisp of M&M Mobile Homes secures the tie-down straps to FEMA disaster-relief housing units at a site in Franklin County near Phil Campbell, Ala. on Monday.
Member Since: July 3, 2005 Posts: 419 Comments: 127371
464. beell
461. WatchingThisOne 11:44 PM GMT on May 14, 2011

The video mentioned using 25 bays of the Morganza structure. There are 125. Far as I know, only one opened today.

Everything seems to be going according to plan from my limited perspective (this laptop, lol!)
Member Since: September 11, 2007 Posts: 141 Comments: 16131
About 2 hours ago...I went with my dad and friend to chase a thunderstorm near Wellington which sparked the severe T-Storm Warning. We caught very heavy rainfall, excessive lightning and wind gusts of up toward 40 MPH at one point. But no damage was sighted except minor flooding on some streets.
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Only one gate open today.
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Quoting beell:


Still just over 100% of the Project Design but probably a good ways from the theoretical limit mentioned in Dr. M's post.

USACE Current High Water Flows
Saturday, May 14th

click for full size graphic


Thanks, beell. Here's hoping that the changes made post-1973 will be sufficient.

It's going to be a long swell. Consequences of a failure are pretty much unthinkable, but that is a large and powerful river. If it gets a foothold somewhere, things could go downhill quite quickly, with huge consequences.

Edit: ok I found a larger picture of that, and I can see where my eyes went astray. The largest wave is a rooster tail kinda thing. One gate.

WTO

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NOAA NWS National Hurricane Center
Only a few more hours until the eastern North Pacific hurricane season officially begins. Tomorrow morning at 5 am PDT NHC will issue the first Tropical Weather Outlook of the season.
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Hey everybody so what's up with the tropics.
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Quoting PcolaDan:


Still just one gate. You can see in the video this picture came from.

That's the plan. They announced at the press conference that they would open one gate that would be least susceptible to scouring. Tomorrow they will open another. Scouring should be less an issue as the water level on the low side rises.

Chicklit had a link to a pre-opening news conference in post 368 going over these details. The news conference at that link has been replaced with video of the opening of the first gate. The news conference is still available on that web page as another link, though.
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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.

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