2011 Mississippi River Spring Floods

[HelmutVII]

_ I know zero about any of this (other than what I've read here), but does any of this discussion take into account the "back up" flooding that ive heard mentioned? And if so, how does that work? And what are the projections as to how much and where? Thanks for all the info guys.

igeaux.mobi _

Backwater flooding is flooding that approaches you from the downstream direction. This happens when the traditional downstream of the river you are on has a higher water level then the traditional upstream locations (traditional upstream and downstream are reversed). This can happen when two rivers are in confluence and one is is a flood state while the other is not. It can also happen with storm surge (the most common form of flooding on the coast). Both cases cause water to flow opposite to the traditional flow direction. Backwater flooding is common in this part of the country because the land is relatively flat.

Given the unpredictability of this flood it pretty hard to tell what the backwater flooding will be. I do suspect that there will be some.

they are now lowering the predicted flood at Butte La rose to 24.5 instead of 27.0. It's still a flood but not as bad. Probably all the new camps will be OK. I know none of the elevations we set in the area were less than 25.0 with most at 27.0. Looks like the older camps will have 3 to 4 feet of water. After this, there won't be any less than elevation 24.0 (depending on where you are) .

[HelmutVII]

_ I am not hating on the math I am just saying that the river & the spillway ceratinly are not rising at the levels that they were projected to according to the dates & levels projected. I understand that we're not out of the woods yet, but its been almost 36 hours since the last argument started & Butte Larose is still at 21.00' & Morgan City is is still well below 9.00' as well as Calumet cut. _

Once the Morganza spillway was opened it was predestined that any level seen downstream (on the Mississippi) of that was not going to get higher and all levels downstream were soon to be labeled as "Cresting" or "Crested". The intention was to operate Morganza so that downstream levels (on the Mississippi) did not rise. As it turns out they are able to do this (so far) with only 17 bays open.

If you go here

http://www.mvn.usace.army.mil/bcarre/morganza.asp

you will see that when they opened the 11 bays the flow rate actually went down because the downstream water elevation had risen reducing the delta H across the structure. As the water levels in the basin rise it will continue to reduce the delta H necessitating more bays to be opened.

Opening Bonnet Carre did the same thing for points downstream of it.

[Bandwagon King]

_ Once the Morganza spillway was opened it was predestined that any level seen downstream (on the Mississippi) of that was not going to get higher and all levels downstream were soon to be labeled as "Cresting" or "Crested". The intention was to operate Morganza so that downstream levels (on the Mississippi) did not rise. As it turns out they are able to do this (so far) with only 17 bays open.

If you go here

http://www.mvn.usace.army.mil/bcarre/morganza.asp

you will see that when they opened the 11 bays the flow rate actually went down because the downstream water elevation had risen reducing the delta H across the structure. As the water levels in the basin rise it will continue to reduce the delta H necessitating more bays to be opened.

Opening Bonnet Carre did the same thing for points downstream of it. _

Not as long as the river downstream on the Mississippi can handle the flow. As long as the Bonnie Carrie remains open, the river will continue to seek the point of least resistance which is straight down stream. The river doesn't know as it goes straight down stream whether it will be diverted to the spillway or down the river channel. The river down stream has begun to outrun the river upstream therefore opening any more bays should be unnecessary. That is what the charts were saying when the river crested @ Knox landing & St. francisville before it crested at Natchez.

The only thing I was worried about in making my call was how much water was strored between Greenville & Vicksburg. I saw the river crested in Vicksburg, but I knew until I saw it make a turn downward there was potential for exteneded enough high flow rate to cause the bays in the basin to have to be open for an extended period of like four weeks. This would cause some problems & could potentially hang us out to dry in a major weather event.

As I have seen the turn downward in Vicksburg I am most confident in saying the river will not see 25' in Butte Larose & won't see 10.5' in Morgan City. I am looking for a crest in the neighborhood of 23.5-24.25 feet in Larose, which is high & it will stay pretty high for about three weeks. I am also looking for the river in Morgan City to top out between 9.80' - 10.25'. This should not cause any flooding of a serious nature at all. I mean if you live in a house 3' from Bayou Boeuf or Bayou Shane on a 6" slab, you may get water in your house, but anyone who has sense enough to have their house at a reasonable base flood elevation should fair fine. MAJOR weather events not withstanding.

[NewsCopy]

BATON ROUGE, La. – Barges broke free from a towboat and the swift Mississippi River current carried them into a bridge as America's busiest inland waterway became even more challenging to traverse. The Coast Guard shut down a 5-mile stretch of the river ...

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[CajunRed]

Kyle...you've had some off the wall predictions over the years...your calls and posts can drive me nuts at times...and (well...you get my point). BUT...on this point of the 2011 flood and what will happen...including how and why...I have to give it to you.

SO FAR, you are correct, sir. For the sake of all those who are directly impacted by this, may you continue to be correct.

igeaux.mobi

[Bandwagon King]

_ Kyle...you've had some off the wall predictions over the years...your calls and posts can drive me nuts at times...and (well...you get my point). BUT...on this point of the 2011 flood and what will happen...including how and why...I have to give it to you.

SO FAR, you are correct, sir. For the sake of all those who are directly impacted by this, may you continue to be correct.

igeaux.mobi _

I appreciate your acknowledgement Cajunred. I also want to thank Big Ed & Mr. Helmut & even some of those whom I may have argued with aliitle bit during this thread. I have great respect for the people who had a part in designing this system & the people who maintain it just like any other person that's out on the front lines & trenches protecting the public safety & property many times with no recognition of the great work they do.

I respect the math & the science that goes into figuring & forecasting flood probabilities & those who are in potentially affected areas would always do well to follow the advice of these people when planning for these types of potentially life changing events.

I also understand the science of flow charts. As I said before, I read them everyday & just because this is a river & not an oil or gas well does not change the characteristics much. As a matter of fact it makes them eerily similar. Water is a fluid just like drilling mud, completion fluid, oil & even natural gas. As such it has specific characteristics which make it behave a certain way.

Charts are the primary indicators of the behavior of any body of fluid & as such DO NOT LIE. I mentioned this before in an earlier post, but many times my safety & the safety of the people who work for me & the ability to control wells depends on the ability to read these flow charts & understand what they are saying. Had the people in charge of the Macondo project understood that those flow charts are the law, because they DO NOT LIE, they would most likely all be alive today.

[NewsCopy]

The couple moved here last summer for a change of pace from their native Lafayette, a city of about 120,000 some ... McInnis, 37, was living in Sulphur, in southwest Louisiana, when Hurricane Rita wiped out her home in 2005. In some ways, she said, the ...

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[NewsCopy]

The final wave of holdouts has mostly packed up and left this Louisiana town as water from the swollen Atchafalaya ... The couple moved here last summer for a change of pace from their native Lafayette, a city of about 120,000 some 60 miles west of Baton ...

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[Bandwagon King]

_ _

It looks like there is more good news ahead. The river levels are starting to break over pretty good & should start dropping more quickly tomorrow & into Monday. The lower the levels get the more quickly they should drop. This is my own take & is not associated with anyone else, but I do believe they will be able to start closing bays on the Morganza pretty soon. Possibly as early as Thursday? They may wait until the river at Baton Rouge gets below a certain level, but Baton Rouge is definitely out of the woods for flooding & this should dictate that no more bays have to be open. They may have some kind of rule of thumb for how many close & how fast, but if the Corps handles the closing like they did the opening, they could likely use the reverse order they had for the openings I imagine.

Let's pray that the upper Mississippi valley doesn't get a whole bunch of rain in the next week.

[Turbine]

The south wind of the last couple days has canals south of Abbeville full to the brim, with flooding in some low lying cattle pastures.

With all the extra water in the gulf I wonder how long it takes to dissipate. If it takes days for the water to get from the locks to Morgan City, it must take weeks and weeks to get out of the Gulf.

I hope we get a late hurricane season, I could see an early hurricane creating a serious storm surge pushing all that water back on land.

[Bandwagon King]

_ The south wind of the last couple days has canals south of Abbeville full to the brim, with flooding in some low lying cattle pastures.

With all the extra water in the gulf I wonder how long it takes to dissipate. If it takes days for the water to get from the locks to Morgan City, it must take weeks and weeks to get out of the Gulf.

I hope we get a late hurricane season, I could see an early hurricane creating a serious storm surge pushing all that water back on land. _

Once again, IMO, we won't be getting a major storm this year. With the amount of cold water coming down these rivers from the north that should cool the GOM surface water sufficiently to not feed any major storms. If history is any kind of indicator, we had Camille in 69' then the 73' flood, then no major storms for a long time. We had Katrina in 05', this flood in 11' hopefully we don't have a major storm for a while.

[NewsCopy]

Their pier already was underwater. The couple moved here last summer for a change of pace from their native Lafayette, a city of about 120,000 some 60 miles west of Baton Rouge. The Bacquets savored their final hours before evacuating by lounging on the ...

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[NewsCopy]

The final wave of holdouts has mostly packed up and left this Louisiana town as water from the swollen Atchafalaya ... The couple moved here last summer for a change of pace from their native Lafayette, a city of about 120,000 some 60 miles west of Baton ...

The rest of the story

[NewsCopy]

We picked up the name "Cajuns" and settled along the rivers, bayous and marshes that provided us a living. We understood and tolerated the high waters and winds, and occasionally, voluntarily, moved away for a short period of time until the wind and waters ...

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[Chop]

You dont need a major storm to cause major problems with storm surge under current conditions.

You dont even need a C 1 hurricane.

A decent tropical storm could cause problems if we get one in the early part of July.
I think by late July everything will be close to normal concerning storm surge.


Dont think conditions exist for anything more then a Cat 2 for the next several years.
Hurricane severity runs in cycles. We have finally hit the quite cycle for about the next 30 years.
Cat 4 and 5 will be rare if ever for many years.