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Looks like the magic 1.5 million cfs point at red river guage
Posted on 5/13/11 at 9:17 am
Posted on 5/13/11 at 9:17 am
will be reached overnight tonite. Its decision time on Morganza. Based on what I've seen they are only planning on opening enough gates to keep the 1.5 mil cfs rate heading toward B.R. It looks like in the next week the top amount of water diverted will be somewhere around 150,000 cfs through the spillway. Anybody know how much water can go through each gate?
4
Posted on 5/13/11 at 9:19 am to lctiger
I guess they don't want to drown the basin too badly but man that is going to be a delicate dance trying to regulate how much is going through.
Posted on 5/13/11 at 9:25 am to lctiger
quote:
Anybody know how much water can go through each gate?
i think the structure can do 600,000cfs through its 125 gates, so do the math
Posted on 5/13/11 at 9:27 am to Croacka
31.25 gates
Posted on 5/13/11 at 9:27 am to Croacka
quote:
i think the structure can do 600,000cfs through its 125 gates, so do the math
Is the math on that that simple?
Posted on 5/13/11 at 9:28 am to Croacka
4,800cfs/gate
Posted on 5/13/11 at 9:29 am to Chad504boy
quote:
Is the math on that that simple?
No. There are a bunch more factors.
Posted on 5/13/11 at 9:29 am to Chad504boy
probably not that simple as I would imagine the pressure head of water is greater with the first gate opened than the last gate to open, but I guess as a rough estimate they will eventually have to open about 30 gates.
Posted on 5/13/11 at 9:30 am to lctiger
31.25 is the rough estimate I came up with 
So somewhere around there seems about right.
So somewhere around there seems about right.
Posted on 5/13/11 at 9:31 am to lctiger
quote:
open about 30 gates.
Thats not 50%....all the inundation maps show the BC open at 100% and the Ganza at 50%...
So now what does this mean as far as those maps go?
Posted on 5/13/11 at 9:31 am to Chad504boy
Given an area A, and a fluid flowing through it with uniform velocity C with an angle ? away from the perpendicular direction to A, the flow rate is:
Q = A x C x cos(theta)
Q = A x C x cos(theta)
Posted on 5/13/11 at 9:33 am to bayoudude
You DO realize that your angle theta is negligible, and the Q just equals VA, right?
This post was edited on 5/13/11 at 9:35 am
Posted on 5/13/11 at 9:34 am to lctiger
quote:
I would imagine the pressure head of water is greater with the first gate opened than the last gate to open
head is simply the difference in elevation
if the first 124 gates havent lowered the level significantly, than it should be near the same flow
Posted on 5/13/11 at 9:36 am to LSUJuice
quote:
You DO realize that your angle theta is negligible, and the Q just equals VA, right?
Negligible or not it is still in the equation don't see why you think it is a big deal.
Posted on 5/13/11 at 9:40 am to tgrbaitn08
the data I looked at only showed estimated cfs at red river through 5/17. at that point the estimate was 1.61 million cfs. If the crest is predicted on 5/22, I guess on that day they will be close to 1.8 million cfs which would be 300,000 cfs through the spillway or 50% capacity.
Posted on 5/13/11 at 9:42 am to bayoudude
And why did you use a C for velocity?
Posted on 5/13/11 at 9:43 am to bayoudude
quote:
Given an area A, and a fluid flowing through it with uniform velocity C with an angle ?
You don't know the velocity, and no you would not use any type of angle to calculate the flow at each gate. It depends on the elevation head (the velocity head will be negligible), the shape and material of the gate, whether there is any tailwater.
Posted on 5/13/11 at 9:46 am to LSUJuice
quote:
And why did you use a C for velocity?
Ask Wiki
Too lazy to leave my desk and grab my fluids book off the shelf. Use your own damn equation if you don't like mine.Posted on 5/13/11 at 9:49 am to bayoudude
quote:
And why did you use a C for velocity?
C normally represents a type of loss coefficient.
Posted on 5/13/11 at 9:50 am to lctiger
I think that they are afraid that if they open it up too much too quickly they will endanger levees below the floodway. I was told that rapidly dropping water will exert a suction type pressure that could cause weak spots to collapse, and that a slow and gradual fall is better. A delicate dance indeed.
Problem with the deal is that with more water pushing on the structure, more water goes through the gate when it opens, so they will likely open a little at a time and try to gauge how much is flowing out before they go on to open more. I think they have a rough idea of quantity but will elect a slow and careful approach.
Problem with the deal is that with more water pushing on the structure, more water goes through the gate when it opens, so they will likely open a little at a time and try to gauge how much is flowing out before they go on to open more. I think they have a rough idea of quantity but will elect a slow and careful approach.
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