2011 Mississippi River Spring Floods

[biged05]

Ok guys...I've been busy riding all day and this is a lot if info to process on a cell phone as I wait to see if our col. Is coming in my area.

Jumbo,
Not sure where you got 660,000 from but you're close as of the readings this morning.. Not sure if it's available to the public so I'll just say it's less than that but the max so far that I know of In this event was almost there.

King,

As much as stages make sense the determination of gate openings is almost 100% on flow in cfs. Sometimes I'd wish they would go a little more on stage readings, but when they talk about trigger points it's all about cfs.

igeaux.mobi

[jumboragncajun]

_ Come back when you have better data than the river levels. Obviously this is the most important piece of information the Corps uses or they wouldn't spend so much time collecting it. _

One more thing. Between the Wax and Atchafalaya outlets, 632,000 cfs is currently being discharged out of the basin.

Coming into the basin is 660k at Old River, 114k at Morganza, 11k from Red River. That is more than what is being discharged. If we assume no more bays are opened, the old river is at max flow, the Red River alone is projected to dump 350k into the basin. That is 492,000 MORE cfs going into basin than what is dumping out of it. To put that in perspective, that is nearly 221 MILLION gallons EVERY MINUTE going in the basin to be stored.

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[HelmutVII]

_ As much as stages make sense the determination of gate openings is almost 100% on flow in cfs. Sometimes I'd wish they would go a little more on stage readings, but when they talk about trigger points it's all about cfs.

igeaux.mobi _

I think that's because the original congressional act referenced flow rates and percentages of the flow rate that is split between the Atchafalaya and Mississippi. I could be wrong though. If that is the case and IF they do it any other way YOU KNOW somebody is going to catch them on it and there will be hell to pay.

It could be a good thing too. Given that hydrologic and hydraulic conditions could vary over time, you could have a different flow rate at the same stage at a given point. It certainly is a model that not only is complex but varies.

[LsuULfan]

_ I think that's because the original congressional act referenced flow rates and percentages of the flow rate that is split between the Atchafalaya and Mississippi. I could be wrong though. If that is the case and IF they do it any other way YOU KNOW somebody is going to catch them on it and there will be hell to pay.

It could be a good thing too. Given that hydrologic and hydraulic conditions could vary over time, you could have a different flow rate at the same stage at a given point. It certainly is a model that not only is complex but varies. _

Seems to be based upon the Project Design Flood

http://en.wikipedia.org/wiki/Project_design_flood

[CajunRed]

That was a helluva chart to the right. I got a little nauseated just looking at it.


igeaux.mobi

[sportsfanatic21]

Is there a RaginPagin dictionary so I can figure out what the hell y'all are talking about?!!!

Seriously, this is the most educational outlet I've seen regarding this situation. Thanks to all that are contributing, and keep it rolling!!!

igeaux.mobi

[HelmutVII]

_ Seems to be based upon the Project Design Flood

http://en.wikipedia.org/wiki/Project_design_flood _

You are correct but they define what a "project design flood" is by flow rate and not stage. And I think that was established in the original 1928 act. I could be wrong though.

However, all of the spliways and flood gates are rated in flow rate. One of the things that defines rate of flow is "Delta H" (difference in head) which can be measured as "Delta stage" (difference in stage). (trying to explain without being too technical. After doing this for over thirty years it's like knowing 2 + 2 is four)

[LsuULfan]

_ You are correct but they define what a "project design flood" is by flow rate and not stage. And I think that was established in the original 1928 act. I could be wrong though.

However, all of the spliways and flood gates are rated in flow rate. One of the things that defines rate of flow is "Delta H" (difference in head) which can be measured as "Delta stage" (difference in stage). (trying to explain without being too technical. After doing this for over thirty years it's like knowing 2 + 2 is four) _

Have not read it yet-but the Wiki footnotes an information paper from the MRC which seems to explain how they came up with the project design flood over the years

http://www.mvd.usace.army.mil/mrc/mr...fo%20paper.pdf

[CharlieK]

The problem for the control structures is they won't flow only what they were designed for. They will flow what they will flow based upon the head (elevation difference) between the two rivers along with other factors. Now if the structures are designed to move 620,000 cfs of water, but the head and flow rate of the rivers forces more than that through the structure there is nothing to stop the water. If this happens they are exceeding the design rating of the structure and it could be damaged. I think this actually happened during the 73 flood. Even though the river was no where near the Project Flood flow rate in 73, the increased head between the two rivers (due to the natural deeping of the Atchafalya channel and rise of the Mississippi) caused the flow through the low sill to exceed the capabilites of the structure. Morganza was opened to relieve this pressure (reduce the head) and the structure survived....barely. It was badly undermined, lost one of the inlet retaining walls, etc. This is why the aux. structure was built.

I'm not saying this IS happening, I'm asking how close we are. There are two issues here one is flooding Baton Rouge, New Orleans, etc., the other is stopping the river from changing course into the Atchafalaya. Honestly the second scares me far more than the first, as it would change life as we know it in Louisiana, and would be a terrible blow to the economy of the country at a time we can ill afford it.