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Started By
Message
re: Morganza Spillway may or may not open for a 3rd time -- lack of clear info from ACoE
Posted on 3/3/19 at 9:47 am to TDsngumbo
Posted on 3/3/19 at 9:47 am to TDsngumbo
I was looking up the Morganza spillway this morning and I was surprised that I think it has only been opened twice. I think 1973 and 2011. I’m amazed at the engineering behind this structure and similar.
I was curious how they measure gallons per minute or water flow rate to determine whether these locks are opened.
I was curious how they measure gallons per minute or water flow rate to determine whether these locks are opened.
3
Posted on 3/3/19 at 10:08 am to TDsngumbo
Just curious, what does this mean for the Amite and Tickfaw rivers?
Posted on 3/3/19 at 10:27 am to cssamerican
quote:
Just curious, what does this mean for the Amite and Tickfaw rivers?
Nothing. Those drainage basins arent flooding.
Posted on 3/3/19 at 10:47 am to Gorilla Ball
quote:
I was curious how they measure gallons per minute or water flow rate to determine whether these locks are opened.
The mathematics governing channel flow are well-known, so they do the calculations to determine what they believe it should be, given the depth of the water and geometry of the river. They can't measure the entire river or even across the width of the river at one location, but there are things like velocity, flow, and level gauges scattered all over the river the scientists use to make sure the river's behaving how the theory predicts it should at the point the gauge is located. When it doesn't behave like predicted (i.e. due to the silting below ORCS), they are able to go out to the river and find out why.
This post was edited on 3/3/19 at 10:51 am
Posted on 3/3/19 at 11:26 am to TigerstuckinMS
Thanks
Posted on 3/3/19 at 11:38 am to TigerstuckinMS
What would be the impact on Southeast Louisiana if the river did divert and go through the Basin? Would the Ports of Baton Rouge and New Orleans cease to exists? What about all points in between.
Posted on 3/3/19 at 12:34 pm to Gorilla Ball
quote:
I was curious how they measure gallons per minute or water flow rate to determine whether these locks are opened.
For most major gages, there are empirical rating curves developed off of measured flow and river stage. For most day to day flow estimates, the stage is measured and flow is calculated using this rating curve.
Here is an unofficial one using USGS Baton Rouge Data:
Flow data is collected using an ADCP mounted to a small work boat that is driven perpendicular to the flow from one bank to the other.
Flow is measured fairly often, so these rating curves are adjusted pretty frequently. During flood events, flow measurements are taken even more frequently. Rivergages.com has a table of all the flow measurements that USACE has collected since 2000, I think...but I cant get the website to work right now, which is not surprising.
Regardless, I'm sure decisions are based on actual measured flow and stage data, not calculated flow using a rating curve or any flow equations.
Posted on 3/3/19 at 12:57 pm to FutureMikeVIII
Posted on 3/3/19 at 1:12 pm to Ponchy Tiger
quote:
What would be the impact on Southeast Louisiana if the river did divert and go through the Basin? Would the Ports of Baton Rouge and New Orleans cease to exists? What about all points in between
It would be an economic and humanitarian disaster. Nobody along the Mississippi is prepared for what could happen. Salinity line would creep farther and farther north, essentially cutting off freshwater supplies to millions of citizens and industrial facilities. The Basin is in no way prepared to handle the brunt of the flow, either.
It's just shitty that this is a problem that has been very well documented and researched but there has been very very little done to prepare for the eventuality of the River changing course.
Posted on 3/3/19 at 1:16 pm to Gorilla Ball
quote:
I was looking up the Morganza spillway this morning and I was surprised that I think it has only been opened twice. I think 1973 and 2011. I’m amazed at the engineering behind this structure and similar.
I was curious how they measure gallons per minute or water flow rate to determine whether these locks are opened.
another thing to be considered when the decision comes to Morganza is the fact that there are literally neighborhoods and towns inside the Morganza floodway
the USCoE will do EVERYTHING to NOT have to open Morganza because they don't want to have to flood those people out
Posted on 3/3/19 at 1:21 pm to PipelineBaw
quote:
It's just shitty that this is a problem that has been very well documented and researched but there has been very very little done to prepare for the eventuality of the River changing course.
Yep. That study was using 1977 dollars and was based on the population and property as it existed in 1980.
A hell of a lot has changed in 40 years, which would put the price tag probably into the trillions.
The hypothetical starts on Page 10 (slightly cut off). Gauge readings are different, but damn if the set up doesn't sound eerily similar to what's shaping up this year.
Posted on 3/3/19 at 2:03 pm to rt3
quote:
the USCoE will do EVERYTHING to NOT have to open Morganza because they don't want to have to flood those people out
Eh, in 2011 it turned out to not be so bad when they opened it
Posted on 3/3/19 at 2:06 pm to Cosmo
quote:
Eh, in 2011 it turned out to not be so bad when they opened it
Part of that was because it was so dry in the basin a lot of it got absorbed.
Isn't like that these days.
Posted on 3/3/19 at 2:11 pm to udtiger
They also have ADCPs mounted on the side of the Mississippi River channel measuring currents. A side looking ADCP can measure out 100m across the river with current flow and direction every meter if that kind of detail is desired
Posted on 3/3/19 at 2:20 pm to Ponchy Tiger
quote:
What would be the impact on Southeast Louisiana if the river did divert and go through the Basin? Would the Ports of Baton Rouge and New Orleans cease to exists? What about all points in between.
Could be relatively nothing. Could be devastating economic, humanitarian, and environmental effects. It really depends on how much of the normal flow would go down the Atchafalaya and how quickly it happened.
The ports, chemical plants, refineries, manufacturing plants, and a nuclear power station all rely on the fresh water of the river for operation. Numerous cities rely on the same fresh water as their water source.
This post was edited on 3/3/19 at 4:32 pm
Posted on 3/3/19 at 2:28 pm to udtiger
quote:quote:
Eh, in 2011 it turned out to not be so bad when they opened it
Part of that was because it was so dry in the basin a lot of it got absorbed.
Isn't like that these days.
if I remember correctly... in 2011 they also ended up opening less Morganza bays than they thought they would have to
Posted on 3/3/19 at 3:02 pm to rt3
That ground was dry and cracked last Morganza opening. It will absorb only a small amount this time not to mention there is a lot of snow to melt and ice dams on rivers to release. If it opens it may stay open longer than the past.
Posted on 3/3/19 at 3:19 pm to TigerstuckinMS
The bottom of the Mississippi River south of Baton Rouge is below sea level. If river flow is reduced by 60 to 70 percent with the main channel becoming the Atchafalaya, saltwater intrusion from the Gulf of Mexico would destroy New Orlean’s source of drinking water and permanently ruin the source of fresh water for industry along the petrochemical corridor south of Baton Rouge.
Posted on 3/3/19 at 3:32 pm to Mudminnow
quote:
That ground was dry and cracked last Morganza opening. It will absorb only a small amount this time not to mention there is a lot of snow to melt and ice dams on rivers to release. If it opens it may stay open longer than the past.
This was reported, but I find it hard to believe it made a significant difference.
Posted on 3/3/19 at 3:48 pm to doubleb
I 100% agree. No way it made a significant difference.
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