2011 Mississippi River Spring Floods

[HelmutVII]

Only Hydrologic models take into consideration antecedent precipitation indexes. Hydraulic models do not and if they do, they probably don't handle it very well.

In any case, the Morganza water has not yet reached Morgan City, we will see what happens. In the mean time the basin is indeed acting as a basin (a hydraulic capacitance) and is doing a very good job.

You are correct in saying that the ethical thing to do is to predict the worst and hope it does not happen. Hurricane forecasters are in the same pickle. To do contrary would be a disservice to the public and border on negligence.

[HelmutVII]

_ I'll have my life vest on in the Mississippi this weekend patrolling around Angola, but I sure as hell ain't jumping in the water. I'll make sure to take pictures to post on here.


igeaux.mobi _

Please do post pics. I am planning on going to Morganza this weekend and will do the same.

I spoke to my brother this evening and he has not gone to Bonnet Carre yet but he told me they structure is working at 105% capacity WITHOUT all the gates open. He said it's really humming and is thinking of going to the structure this weekend. He also said the water is cascading out of the spillway just south of the interstate at the tree line.

He also said that none of the fresh water diversion structures are in operation. Their capacity is so small that it would make little difference. Also, the delta H on the structure would be so big that it would probably damage the structure if it was opened. It would also kill the oyster beds that were just reseeded after the BP mess last year. To open them up now would just about put an end to all oyster fishing in the area.

[jumboragncajun]

I do know that levels in a pipe of known or uniform cross sectional area and length and known fluid properties can tell you everything you need to know. That is NOT open-channel flow. Many many other variables that had been repeatedly mentioned by myself, big ed, and others that are obviously experienced and informed , contribute to create the levels......at a single particular location... why is that so effin hard to comprehend. It's just like you to turn the convo into something to a subj you might know about. ie oilfield.

When I say I don't need to study charts because I understand the science that makes the effin charts.

Can I tell you what the water level in Butte LaRose will be? No. I never said I could. There are too many unknown variables for ME to determine that. If you give me all the unknowns, it can easily be determined. All I was saying is that your approach is flat out wrong. And normally, I listen or read your spewed conjured ideas that you claim to be hard facts, and don't think a thing about it. But you get on a keyboard and start telling people with 30+ yrs exp in this field that they are wrong because you read a chart, I'm just politely telling you that your reasoning/basis is wrong. That's it. Your too dense to have a conversation with. Frankly, you lost all credibility with me in an earlier post that clearly showed your lack understanding of how this basin system works. Not worth the time arguing after that. If you asked questions, that'd be one thing, plenty here have....but you adamantly proclaim....and then condemn..... On this topic and any other.



igeaux.mobi

[phideaux]

When I say I don't need to study charts because I understand the science that makes the effin charts.
igeaux.mobi _

Rack him!

[Bandwagon King]

_ Ok this is going to be a ling one and I'm typing on my phone also hopefully I don't Repeat anything b/c I know other posts are coming in.

King,

The determination of how many gates to open is based on flow. Is flow and stage related? Yes but it's all about flow. Let's see if I can show you why in my opinion. A river is dynamic we all know that it changes in width and depth therefore the height needed to pass the water (flowline) changes. We are actually looking at some sections of river now where it appears the river bottom may actually be rising and it's not the usual shoaling in. We use flow as indicated by the project flood diagram. Here is one example of why flow is used. When we opened morganza the head on the gates were very high...let's say 20' just for discussion. Now when they opened the first gate there was about 10,000 cfs flowing thru it. Then a second was open and it was about the same thru that one. Now we've opened more gates the head has been reduced with water levels on the opposite side getting higher, therefore the flow thru each gate has been reduced. So what they do is take a measurement upstream and one downstream of the structure to make sure the flow does not exceed 1.5 mil cfs. If they did not open any more gates as the water levels on each side equalized then we would force more than 1.5 mil cfs thru the system below morganza and yes in turn make the water levels rise. But it is based on a total cfs. I hope that part is a little more clear now. Can we adjust downstream levels with the gates or in the case of bonne carre bays? Yes they are doing that now. They are trying to keep the river at the carrolton gate around 17'. So they have opened more bays there to allow less flow past new Orleans so the coast guard can keep the channel open. Can it handle the 1.25 mil south of bonne carre? Yes but to keep everything open and to try and affect industry the least we are passing more thru bonnet carre.

Now as far as Morgan city and calumet are concerned, they are not keeping up. How do I know the? 1) I've been watching water levels in the basin for a while now and today watched the water along the west basin levee again. 2) it can't handle water that is coming in but has not reached there yet. The water from morganza as of this morning had not made it to I-10 yet. So the river has yet to be affected by the water from morganza, much less the river being affected in Morgan city and calumet. Jumbo's thinking does not sound off. I don't really have the time to look over all the charts and information we have out there and make better points, just too damn busy with the water itself. I'll be honest and say from the new predictions and other things I'm seeing the crest predictions may be a little high, but I'm not going on just the charts your looking at. Let's hope that's true but I wouldn't count on it. The next few days will start to tell the story.

I know I've forgot some of the things that I wanted to say, but my mind is running in too many directions right now.

igeaux.mobi _

Once again I've misspoken. When I say the river at Morgan City & Calumet are handling it just fine, from the numbers I am seeing that between the shear volume the basin can handle plus the amount of water passing through Morgan City & Calumet, plus the fact that there is a lot of water being absorbed by the vegetation & the groundnd it looks very good for Butte Larose, Amelia, & Stephensville right now. I am also very encouraged that the Corps is working this thing in such a coordinated way, looking at all the data to make its decisions. You can see the tools such as satellite imagery, computer modelling, electronic readings up to the minute, & a host of other tools helping you guys in your information gathering & decision making.

[Bandwagon King]

_ Mathematically Q (quantity) = V (velocity) x A (area). The problem in large rivers (like the Mississippi) is how do you measure velocity? It can vary substantially from one point to another at any given section. So what you have to do is take velocity measurements at many points to get a velocity profile at a give section. The next thing to do is to determine the area. The problem is scour, how much and how is it affecting the cross section of the river. So what they are doing is making and ESTIMATE of flow rate given an ESTIMATE of the cross sectional area of the channel and using the velocity profile. This is not an exact science and it borders on an art.

If the slope of the hydraulic grade line is high then the velocity is high and will produce a higher flow rate for a given area. If the cross section is scoured then the area is greater and can also produce a higher flow rate (again in those areas not affected by tide ---generally those areas were the bottom of the channel is greater than 0.00 msl) _

This is exactly what I have been saying. The flow rate estimates are very important & are the basis for projecting flood stages as far as I would know. The river levels themselves are either the confirmation or contradiction to those flow rate estimates. The math is theory the water level is fact.

[NewsCopy]

But not everyone is as prepared as these two Cajuns to meet the rising brown waters of the Atchafalaya River. They don't need sandbags. They have a freezer full of Fudgsicles, three generators and a flat-screen TV. The brothers plan to ride out the coming ...

The rest of the story

[CajunRed]

Jumbo...I appreciate,and I am sure many other, appreciate the info you have provided. Looking forward to ongoing updates and analysis.


igeaux.mobi

[NewsCopy]

Everywhere you put a trap, you got filled up,” he said. Yet Jay Huner, 65, a marine scientist and former director of the University of Louisiana at Lafayette Crawfish Research Center, recalled a darker side to that flood. “You literally could not give ...

The rest of the story

[CharlieK]

Ok sounds like the old river structures are flowing 661,000 cfs. Originally there were only two structures (low sill and overbank) which combined were designed for 620,000 cfs. Now there are two more structures (aux. and the hydro plant) that can flow an additonal 520,000 cfs. So we are at 661,000 out of a designed 1.14 million. Does that sound right Helmut et al?

http://www.mvn.usace.army.mil/bcarre...ht-19may11.pdf

[Turbine]

That is a whole lot of H2o

igeaux.mobi

[Bandwagon King]

_ Ok sounds like the old river structures are flowing 661,000 cfs. Originally there were only two structures (low sill and overbank) which combined were designed for 620,000 cfs. Now there are two more structures (aux. and the hydro plant) that can flow an additonal 520,000 cfs. So we are at 661,000 out of a designed 1.14 million. Does that sound right Helmut et al?

http://www.mvn.usace.army.mil/bcarre...ht-19may11.pdf _

I have a question about the old river control structure. I have seen that the estimated flow through just that structure to be as high as 660,0000 CFS. which is like 110% of the capacity. How can something flow at 110% of its capacity. Isn't that like giving 110% on the field?

Is it not possible that they are talking about the OCS combined with the turbine plant?