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re: Morganza Spillway may or may not open for a 3rd time -- lack of clear info from ACoE
Posted on 5/23/19 at 12:39 pm to CM Tiger83
Posted on 5/23/19 at 12:39 pm to CM Tiger83
quote:
Does anyone know how much lower the BR gauge will drop if/when they open the Morganza? Any chance it could drop it below 40’?
This opening is not like the last time so.... Last time they opened just enough bays to keep the river from rising any more in BR and down stream and maintain the threshold. So it maintained height and i think maybe even dropped a half foot or so. This time is different so not sure if anyone really knows.
1
Posted on 5/23/19 at 12:41 pm to FelicianaTigerfan
How is it different? I'm just trying to catch up on the thread
Posted on 5/23/19 at 12:45 pm to LSU Tigershark
quote:
How is it different? I'm just trying to catch up on the thread
I think, from what I've read, that this time they're wanting to simply prevent the Morganza from being overtopped more than they want to lower levels downstream. The ORCS is already operating at maximum capacity diverting some to the Atchafalaya so they can't use that any more than they already are.
You see, the river is already extremely high and there's lots of rain forecast upstream. If they don't do something with the Morganza, it will be over topped and subsequently destroyed when that extra flow gets here.
Now obviously if that happens then the level in BR and NOLA would also increase to dangerous levels as well but that's only a secondary concern at this point, I believe.
Posted on 5/23/19 at 12:50 pm to slackster
quote:
They don't think ORCS is in any danger, for starters. They open Morganza WELL before there is any real threat to ORCS.
Bingo. The only people who think the ORCS may fail are the fear mongerers in this thread.
Posted on 5/23/19 at 12:50 pm to LSU Tigershark
There is a threshold of when they can open Morganza. There has to be a certain cubic feet per second of flow in the river and it has to be a certain height. They reached that last time. The river isnt flowing at that high of a rate currently, and ist as high, but its threatening to possibly top the spillway ( considering future rainfall and watershed). Last time when it reached its threshold it was close but that wasnt discussed
I have no idea if I explained that right but basically 44 is the new 47
I have no idea if I explained that right but basically 44 is the new 47
This post was edited on 5/23/19 at 12:52 pm
Posted on 5/23/19 at 1:20 pm to PhiTiger1764
quote:
The only people who think the ORCS may fail are the fear mongerers in this thread.
The general silting condition that is as at Morganza exists at ORCS as well.
The only way to fix that is to dredge- a lot. USACE doesnt have the capacity to dredge both above and below BR, so eventually this is a topic that is going to be decided either by mother nature or the corps.
Posted on 5/23/19 at 1:21 pm to FelicianaTigerfan
The real problem is that with the silting going on, the bottom of the river is higher than it was in the past, leading to higher river stages with identical flows... which is going to cause a problem for both ORCS and Morganza.
Posted on 5/23/19 at 1:30 pm to NYNolaguy1
quote:
The real problem is that with the silting going on, the bottom of the river is higher than it was in the past, leading to higher river stages with identical flows... which is going to cause a problem for both ORCS and Morganza.
My mind implodes when I try to imagine the ways dredging would take place in a river as violent and large as the Mississippi River even when it's "gentle".
Dumb question: is the sediment build-up at the bottom of the river a partial result of the levee system not allowing the river to go where it wants? In other words, would the build-up occur with or without the levee system?
Posted on 5/23/19 at 1:33 pm to NYNolaguy1
The gradient from Morganza to the atchafalaya channel is much more steep than the mississippi's normal gradient downriver. If Morganza failed to limit flow and a channel were to scour, I dont think the river could be stopped from going to the atchafalaya permanently at that point.
Something not talked about much in these discussions is that the Atchafalaya channel has scoured and become much deeper in recent decades, making the gradient problem worse. Basically the MS river wants to go down the Atchafalaya even more so now than it did in 1979 or even 2011. The difference in height between river beds is what causes the river to want to flow in that direction, and it isn't just due to sedimentation. The atchafalaya in the area from ORCS down past morganza is actually scouring and losing sediment and becoming deeper!
Something not talked about much in these discussions is that the Atchafalaya channel has scoured and become much deeper in recent decades, making the gradient problem worse. Basically the MS river wants to go down the Atchafalaya even more so now than it did in 1979 or even 2011. The difference in height between river beds is what causes the river to want to flow in that direction, and it isn't just due to sedimentation. The atchafalaya in the area from ORCS down past morganza is actually scouring and losing sediment and becoming deeper!
This post was edited on 5/23/19 at 1:35 pm
Posted on 5/23/19 at 1:34 pm to TDsngumbo
quote:
Dumb question: is the sediment build-up at the bottom of the river a partial result of the levee system not allowing the river to go where it wants?
Yes. Without the levees, the river could dump that sediment elsewhere during floods.
Posted on 5/23/19 at 1:36 pm to TDsngumbo
quote:
My mind implodes when I try to imagine the ways dredging would take place in a river as violent and large as the Mississippi River even when it's "gentle".
They dredge areas along the New Orleans riverfront all the time. I assume other places where deep draft ships need to dock as well.
I guess the scope of what is being contemplated on this other deal is much greater, though. But, logistically, it's clearly doable.
Posted on 5/23/19 at 1:40 pm to fillmoregandt
quote:
Yes. Without the levees, the river could dump that sediment elsewhere during floods.
Huh -- well I guess the levee system really did come at a cost. Saves literally trillions of dollars in flood damage over the years but eventually they must either be built higher and wider, feds must buy out everyone within 300 yards of each levee side to build a secondary higher levee, dredge silt from the bottom of the massive river for over a hundred miles or more, or eventually see the control structures fail in some way allowing for the permanent re-routing of the river.
All of those options come at an enormous cost. Which one is cheaper?
This post was edited on 5/23/19 at 1:42 pm
Posted on 5/23/19 at 1:51 pm to Y.A. Tittle
quote:
They dredge areas along the New Orleans riverfront all the time. I assume other places where deep draft ships need to dock as well. I guess the scope of what is being contemplated on this other deal is much greater, though. But, logistically, it's clearly doable.
There has been a huge dredging ship at the Head of Passes, below Venice where the mouth of the river splits into is 5 main mouths, for as long as I’ve been fishing down there. It appears to run 24/7/365, trying to keep shipping lanes open.
Every time I pass, I wonder who has that contract? Never ending contract. How much money is someone stacking up doing this?
Dredging from Simmesport to BR would be a task of such monumental proportions it would be building the pyramids level monumental.
A huge national commitment!
Posted on 5/23/19 at 1:54 pm to FelicianaTigerfan
(no message)
Posted on 5/23/19 at 1:56 pm to WoWyHi
Stop what? What does your post have to do with anything in this thread?
Posted on 5/23/19 at 1:58 pm to FelicianaTigerfan
quote:
The idea of the ORCS failing and Morganza opening arent related as I understand it. Now, if Morganza is over topped thne maybe it could erode the back side and fail
I never said anything about the ORCS failing. I said the structure at Morganza could fail if breached or if the levees of the forebay were breached. I also think opening some or all of the gates puts the integrity of the gates at risk, just due to age.
Posted on 5/23/19 at 2:04 pm to tgrbaitn08
tell you the truth i havent looked at what the water is doing right now. but from a quick google search that better be one huge barge.
I see they want to put a barge gate there on the south east side of Avoca Island.
I see they want to put a barge gate there on the south east side of Avoca Island.
Posted on 5/23/19 at 2:07 pm to BallsEleven
quote:try selling this to communities. Morgan City is just experiencing a slow death. subsidence is occurring and it is not being replenished.
If it's only a matter of time before it corrects itself any way, at least let it be on our terms and allow communities/industries to adjust accordingly over years instead of an extreme event and it happen all at once.
Posted on 5/23/19 at 2:09 pm to TDsngumbo
quote:
Dumb question: is the sediment build-up at the bottom of the river a partial result of the levee system not allowing the river to go where it wants? In other words, would the build-up occur with or without the levee system?
For me, the notion/reality that the river, left unchecked, will find the steepest path to the ocean is both mind-blowing and amazingly simple/obvious, given the implications of such an event.
Also, man vying against nature, in this way and more broadly, is something that I don’t believe we give enough thought to, given how much of our current reality depends on it.
Posted on 5/23/19 at 2:12 pm to CarRamrod
The existence of Morgan City as a viable economic entity versus the existence of everything south of Morganza on the Mississippi River as one, should not be that difficult a proposition. I'm not saying this as someone with any particular animus to Morgan City either.
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