2011 Mississippi River Spring Floods

[HelmutVII]

_ So you're saying the ORCS is always channeling water? _

Well Yes it is actually.

[NewsCopy]

MEMPHIS, Tenn. – The Mississippi River crest has passed through the South, but the misery caused by flooding is far from over. As water recedes, residents from Tennessee to Louisiana face the task of gutting houses soaked in polluted water. Farmers will ...

The rest of the story

[HelmutVII]

_ This has probably been asked aleady, but have they used the overbank structure? Also, wouldn't it be fair to say that now that the Atchafalaya has crested & is receding in Simmsport above the Morganza & the river is still going down in Baton Rouge that the Atchafalaya & lower Mississippi are capable of handling the flow rate & they can now start looking at closing the gates on the Morganza? _

I don't know the exact operating plan but I would suspect that they wouldn't think of closure until the total flow through all structures results in less than 1.5 million cfs at Red river landing including the normal 70/30 split at ORCS. There is an operational plan and it has been reviewed and approved. I'm sure there are people out there watching very closely for any deviation. If they deviate then there will be hell to pay.

What's the hurry to close? They have a spillway and a floodway, so why not use it? The water is behaving better than expected. Even if they close Morganza, ORCS will still be  ing large amounts of water into the Atchafalaya probably into late June or early July.

Bonnet Carre is still open and operating above design flow will probably stay open for a good while longer. At least until such time that they can safely put the pins in place.

[CajunRed]

BigEd...for anyone out there who doesn't know or understand the full history of the three rivers and the structures that regulate them, THIS is the best piece I've ever seen. I thought I knew much of the above. Turns out that I knew way less than I thought. This should be read by all south Louisianians.

Orcs keeps the 70-30 split. This article is a pretty good one.

http://www.americaswetlandresources....erControl.html

igeaux.mobi

igeaux.mobi

[biged05]

_ BigEd...for anyone out there who doesn't know or understand the full history of the three rivers and the structures that regulate them, THIS is the best piece I've ever seen. I thought I knew much of the above. Turns out that I knew way less than I thought. This should be read by all south Louisianians.
igeaux.mobi _

It was a great read. It reminded me about things I had forgotten about.

[biged05]

_ I don't know the exact operating plan but I would suspect that they wouldn't think of closure until the total flow through all structures results in less than 1.5 million cfs at Red river landing including the normal 70/30 split at ORCS. There is an operational plan and it has been reviewed and approved. I'm sure there are people out there watching very closely for any deviation. If they deviate then there will be hell to pay.

What's the hurry to close? They have a spillway and a floodway, so why not use it? The water is behaving better than expected. Even if they close Morganza, ORCS will still be  ing large amounts of water into the Atchafalaya probably into late June or early July.

Bonnet Carre is still open and operating above design flow will probably stay open for a good while longer. At least until such time that they can safely put the pins in place. _

You're right, there is an OP plan and if we want to change it we have to get a deveation granted, and if we don't there are enough people looking and hell would be paid!!

I'm not sure what the OP plan actually states, but it is tied in to the 1.5 mil cfs flowing past Red River landing.

Also, the overbank structure is not being used at this time. There is leakage through the needles, but it is not being operated.

[CharlieK]

_ You're right, there is an OP plan and if we want to change it we have to get a deveation granted, and if we don't there are enough people looking and hell would be paid!!

I'm not sure what the OP plan actually states, but it is tied in to the 1.5 mil cfs flowing past Red River landing.

Also, the overbank structure is not being used at this time. There is leakage through the needles, but it is not being operated. _

Biged, Helmut, Civil.....I had heard somewhere but can't find it that it is some engineers opinion that the structure (the original low sill and overbank) were put in a less than optimum spot in the river. They stated that this was done for economic reasons. Not much else was explained. Is this based on it being on the inside bend of the river and if so why would this be less than optimum?

[NewsCopy]

Government inspections must take place before many homeowners can return, a process that could take a week. Story: Cajuns to blame for their own flood misery? Not so fast State officials say 1,664 primary residences have been evacuated, but it's not clear ...

The rest of the story

[HelmutVII]

_ BigEd...for anyone out there who doesn't know or understand the full history of the three rivers and the structures that regulate them, THIS is the best piece I've ever seen. I thought I knew much of the above. Turns out that I knew way less than I thought. This should be read by all south Louisianians.






igeaux.mobi _

I always thought if they built a stadium there they could call it "Three Rivers Stadium".

[HelmutVII]

_ Biged, Helmut, Civil.....I had heard somewhere but can't find it that it is some engineers opinion that the structure (the original low sill and overbank) were put in a less than optimum spot in the river. They stated that this was done for economic reasons. Not much else was explained. Is this based on it being on the inside bend of the river and if so why would this be less than optimum? _

I'm thinking if they put it on an outside curve it would have been lost many years ago. Putting it on an inside curve makes it prone to silt build up.

As usual, there is optimum design, and the design you can afford to build. Usually, the design you can afford to build wins out. The trick is to make the design you can afford to build work for its intended purpose. This is where the ingenuity part of being an Engineer comes into play. The most important thing they teach you in Engineering school is to not teach you how to think, but teach you how to think critically. A fine line to be sure but there is indeed a line.

[CharlieK]

_ I'm thinking if they put it on an outside curve it would have been lost many years ago. Putting it on an inside curve makes it prone to silt build up.

As usual, there is optimum design, and the design you can afford to build. Usually, the design you can afford to build wins out. The trick is to make the design you can afford to build work for its intended purpose. This is where the ingenuity part of being an Engineer comes into play. The most important thing they teach you in Engineering school is to not teach you how to think, but teach you how to think critically. A fine line to be sure but there is indeed a line. _

As a mechanical design engineer I understand what you are saying about the fine line and the need for engineering ingenuity to overcome more than just the techincal challenges but also the economic. What I am asking was specifically what was the limitation of the spot they ended up settling on, and what would have beena better spot. I understand it was a compromise, and I am by no means saying it wasn't done properly, I'm just interested in the technical aspects of this.

Thanks again for your insights.

[Bandwagon King]

_ Well Yes it is actually. _

I knew they were flowing through the power plant. The low sill still operates 24/7 ?