2011 Mississippi River Spring Floods

[Bandwagon King]

_ A little change of subject---BUT there is an expectation of huge flooding due to the incredible amount of snow now melting in Colorado----Will we get any of this or does the cont. divide send it only to the West???? _

I believe the Colorado river travels through Texas to the GOM. There are a lot of thirsty rivers & dry country between us & them.

[biged05]

King,

Where are you seeing the one foot drop? At morganza the staff Gage was 59.2 the morning we opened and it was 59.3 yesterday morning. Or are you referring to somewhere in the river?


igeaux.mobi

[HelmutVII]

_ Once again, I'm going to post the the link to the river gauges. I suggest anyone who wants to understand what is actually going on with the Mississippi & the Atchafalay & it's outlets to check these level charts. They tell a very specific story. The story is that the Corps has everything well in hand like it is now & should have the river where Mr. Helmut took his pictures to the top of the gates within the next 3-4 days if they are not there now. I have been to the gates also & they start about 2 -2 1/2' below the surface of the road. I also have pictures form when we went last Saturday when they opened the first gates & I can say that the water is down almost a foot from where it was when they first opened. The level actualy went up another quarter to a half a foot after the first two gates were open then crested. & is now where Helmut took his pics.
http://www2.mvr.usace.army.mil/Water...new/layout.cfm _

Yes they do tell a story and that story is every station north of Baton Rouge is above flood stage. Some of them by over 10 to 12 feet. That water has to go someplace and that is the lower Mississippi or Atachafalaya basin. No matter what there is a significant amount of water YET to come down here. If that means using the Morganza floodway then so be it. After all, it is a floodway and people that have an interest there do so at their own risk. Also, any station upstream of Red river landing is referenced to a local zero NOT NAVD88.

Granted the river levels are going down and the trend is down in most areas (some predictions at a few stations in the upper reaches of the Mississippi have it going up a little bit in the next week or so). But, the whole thing is based on flow rates and if the flow increases at Red River landing go over 1.5 million cfs then they will have to open more gates. I'm not saying this is going to happen, but it could.

[Bandwagon King]

_ Yes they do tell a story and that story is every station north of Baton Rouge is above flood stage. Some of them by over 10 to 12 feet. That water has to go someplace and that is the lower Mississippi or Atachafalaya basin. No matter what there is a significant amount of water YET to come down here. If that means using the Morganza floodway then so be it. After all, it is a floodway and people that have an interest there do so at their own risk. Also, any station upstream of Red river landing is referenced to a local zero NOT NAVD88.

Granted the river levels are going down and the trend is down in most areas (some predictions at a few stations in the upper reaches of the Mississippi have it going up a little bit in the next week or so). But, the whole thing is based on flow rates and if the flow increases at Red River landing go over 1.5 million cfs then they will have to open more gates. I'm not saying this is going to happen, but it could. _

Is your scenario possible? Possibly, but I doubt it highly. Why, because they waited so long to open Morganza to begin with. Why? Probably because the rise in the river did not coincide completely with the estimated flow rates. The river in New Orleans, Baton Rouge, & all points north has been above flood stage for days & days. That is what the levee system is for, to keep the river in its banks even if it goes above flood stage. Where the problems occur is when the river goes over the levees or they have to blow levees up to get the land to take on extra water in some spots.

The river is only rising locally again well up the Mississippi where there has been some large amounts of precipitation falling over the weekend. I don't knlow for sure how those will affect the overall process untill they get down to Arkansas City, but that is going to 4 or 5 days & we will see that as it comes. This is a totally different matter. According to the charts the river in Natchez & Vicksburg is going to start dropping big time. In a few days it will be dropping by as much as a foot a day. How do I know? becuase that is wat it is doing all up & down the river farther north. As long as there are no major stalled fronts this will continue to happen.

You have to give this thing a few days to see the effects. I just wish this crazy Southerly wind would quit. If this wind keeps up, it will be the people in lower Iberia, West St. Mary, & points west of there that could experience local flooding. Why? because the natural current of the river flows westerly.

I'm gonna mention this & people can take it for what its worth, But I seem to remember the floods of 73'. The thing I remember that spring is there was a ton of rain locally. I mean, I remember crawfish were all over the road all over Terrebonne parish. people were able to take sacks & pick all the crawfish they could eat off the shoulders of the road. That isn't happening now. I don't know what will happen if this wind continues, but that is something no one has mentioned that could come into affect.

[Bandwagon King]

_ King,

Where are you seeing the one foot drop? At morganza the staff Gage was 59.2 the morning we opened and it was 59.3 yesterday morning. Or are you referring to somewhere in the river?


igeaux.mobi _

Big Ed, I am seeing the drops all up & down the river. I went to the very spot where Helmut took the pics he posted. We were one of the first vehicles they allowed over the structure after they opened the gates last week. I can assure you the water was higher then & went up even further after they opened the first two gates then it is form the picture Helmut took yesterday. I have the pics in my phone & on my computer, but I don't remember the site my nephew went to change the images to a small enough file to download them on this thread. You can plainly see the water about 3-4' closer to the shoulder of the road in the pics we took. that road is a levee road & has a slope of what 2-1 or 3-1? that means if the pictures show a 3-4' difference in distance from the shoulder the depth level would be what 8"-1'. Possibly alittle more. The gauge data at Red River landing shows this. The gauge data at Knox Landing shows this. The gauge data @ Baton Rouge shows this. You can't have a decrease up the river from you & down the river from you & you not be going down also. It is a physical impossibility.

Give this thing a little time. The levels will be going down by 1/2' a day within 3 days. By Wednesday evening the level in Baton Rouge will be at or below 43.5' unless it rains, guaranteed. The level in Natchez will drop by almost 2' within the next three days. The lower the river the less square footage at the surface. This means every time it goes down an inch the volume change differs immensely. Especially if you are dealing with an area that has had back water flooding due to the river topping its banks. The good thing about it for us is a lot of that water will never be put back into its banks & will stay in back water sloughs for months. Likewise, every time the water goes up in the basin the more area you have to cover to make it go up another inch. I just don't want to see the corps raise the level to the point in the basin above necessary. every inch the water goes up in the basin now, squeezes the room the mamals have to get away from it by huge amounts of acreage. If it gets up to even 24' the devestation to wild life will phenominal.

I believe in what the corps has done so far & I believe they will do the best thing throughout the rest of this. The ball is totally in their court because they have the river totally under control from here. How do I know? because the level in Baton Rouge has been going down now Since Wednesday night. To open anymore flood gates right now would be totally unnecessary from what I see.

[HelmutVII]

_ Is your scenario possible? Possibly, but I doubt it highly. Why, because they waited so long to open Morganza to begin with. Why? Probably because the rise in the river did not coincide completely with the estimated flow rates.

The trigger point for opening Morganza is not river stage, it's flow rate. That flow rate is 1.5 million CFS in the Mississippi River at Red River Landing. What is of concern now is volume of water not elevation. There is still plenty of water out of banks in the upper reaches of the river and it will take some time to get here. So water levels will be high for some time to come.

Flow rates in open channel regimes are dependent upon many things one of the most important is the slope of the hydraulic grade line. That is, in general terms, the slope of the water surface. Given that the crest has already happened and the water surface at Red River landing is lowering it is resulting in an increased slope in the HGL. The increase in slope of the HGL could cause an increase in flow in the Mississippi.

What I'm saying is, don't count your chickens before they hatch. We have seen the high point of the water but possibly not the high point in flow rate. Flow rate is the controlling factor in the operation of Morganza. Open channel flow is very unpredictable because we are dealing with variable flow areas, variable flow velocities and variable HGL slopes. In addition to variable winds and tides as we get closer to the coast. That's why we have to wait and see. If they don't have to open any more Moganza gates then that's fine. But if they do I won't be surprised. If they do, it will be based on being able to maintain no more than 1.5 million CFS of flow in the Mississippi River at Red River Landing. (Unless there is some other circumstance like a problem at ORCS)

[Bandwagon King]

_ The trigger point for opening Morganza is not river stage, it's flow rate. That flow rate is 1.5 million CFS in the Mississippi River at Red River Landing. What is of concern now is volume of water not elevation. There is still plenty of water out of banks in the upper reaches of the river and it will take some time to get here. So water levels will be high for some time to come.

Flow rates in open channel regimes are dependent upon many things one of the most important is the slope of the hydraulic grade line. That is, in general terms, the slope of the water surface. Given that the crest has already happened and the water surface at Red River landing is lowering it is resulting in an increased slope in the HGL. The increase in slope of the HGL could cause an increase in flow in the Mississippi.

What I'm saying is, don't count your chickens before they hatch. We have seen the high point of the water but possibly not the high point in flow rate. Flow rate is the controlling factor in the operation of Morganza. Open channel flow is very unpredictable because we are dealing with variable flow areas, variable flow velocities and variable HGL slopes. In addition to variable winds and tides as we get closer to the coast. That's why we have to wait and see. If they don't have to open any more Moganza gates then that's fine. But if they do I won't be surprised. If they do, it will be based on being able to maintain no more than 1.5 million CFS of flow in the Mississippi River at Red River Landing. (Unless there is some other circumstance like a problem at ORCS) _

Once again, I hate to continue this but above flood stage does not mean out of its banks. The Mississippi has a massive levee system that is used to keep the river in check even when it goes above flood stage. The river has been above flood stage in Baton rouge for weeks now, yet ther are people working in downtown Baton Rouge this morning in buildings that would be inundated without the levees.

What is the point of ESTIMATING flow rates? to determine what the level of the river will be ahead of time. The level of the river is either proof or disproof of those flow rates. That is why I have said before & will say again, the charts don't lie. If the river is going down then why do you need to open the gates? The only possible reason for opening more gates now would be to cause the basin to take on even more water faster than it is now. WHY? The river is going down in Baton Rouge as well as New Orleans. The river is below 17.00' consistently for the first time in weeks in New Orleans. This is proof that the flow rates down stream are greater than they are upstream.

I will say this also about flow rates. Its impossible for a structure, any structure to allow more than 100% capacity though it. Unless you have a positive displacement meter you cannot estimate flow rates to more than 90% of accuracy. In this case that is millions & millions, & millions of gallons of water per day. How do I know this? I have pumped hundreds of thousands of barrels of water in my life & I can tell you for a fact that nothing compares with tank levels when figuring volumes. In this case the river upstream is one tank. The river down stream is another. The levels in those tanks are telling me which one is winning. If the levels rise the river upstream is giving more water than the river downstream can handle. time to open gates. If the river downstream & the river upstrem are going down then it is time to start thinking about closing gates. It is that simple. Otherwise the corps would have already opened the extra gates.

[Turbine]

_ I will say this also about flow rates. Its impossible for a structure, any structure to allow more than 100% capacity though it.

I thought there was something called structural design capacity. This is not to say it couldn’t handle more than its STC, only that the results of going over, could not be sustained indefinitely.

What am I missing here?

[Bandwagon King]

_ I thought there was something called structural design capacity. This is not to say it couldn’t handle more than its STC, only that the results of going over, could not be sustained indefinitely.

What am I missing here? _

When a structure like that is designed the area of the structure is the basis for figuring the amount of fluid that will go through it. The hydraulic head will have a small effect, but you can't put more than the square footage of the of openeing will allow per second. Factors that are not take into account, but have a definite affect on calculating flow rates through that structure are friction & oxidation of the water as it passes through.

The reason the water foams up when it is coming through a differential structure like that is from the water oxidizing. The greater the pressure the more the oxidation. There is also friction tension which takes place as water passes through the control structure. These account for small percentages of the overall flow , but take away from the CFS the structure is handling to begin with. The greater the head, the higher the differential, & the greater the area of flow, the more these factors are present.

That is why the only true way to figure volumes is by positive displacement. There is no controlled way to figure either of these since the factors change every second. You can make an educated guess & its a darn good one about what will happen by these calculations, but the levels tell you if you are overcoming the feed from upstream or not, better than anything else. That is why they are so important. They provide with certainty that you are either getting rid of water faster than it is coming to you or not.

I didn't want to get into this stuff & left it alone although I knew this days ago. It is part of every engineering equation for my industry as much as Velocity X Area would be.

[CharlieK]

_ When a structure like that is designed the area of the structure is the basis for figuring the amount of fluid that will go through it. The hydraulic head will have a small effect, but you can't put more than the square footage of the of openeing will allow per second. Factors that are not take into account, but have a definite affect on calculating flow rates through that structure are friction & oxidation of the water as it passes through.

The reason the water foams up when it is coming through a differential structure like that is from the water oxidizing. The greater the pressure the more the oxidation. There is also friction tension which takes place as water passes through the control structure. These account for small percentages of the overall flow , but take away from the CFS the structure is handling to begin with. The greater the head, the higher the differential, & the greater the area of flow, the more these factors are present.

That is why the only true way to figure volumes is by positive displacement. There is no controlled way to figure either of these since the factors change every second. You can make an educated guess & its a darn good one about what will happen by these calculations, but the levels tell you if you are overcoming the feed from upstream or not, better than anything else. That is why they are so important. They provide with certainty that you are either getting rid of water faster than it is coming to you or not.

I didn't want to get into this stuff & left it alone although I knew this days ago. It is part of every engineering equation for my industry as much as Velocity X Area would be. _

You are simply wrong. The old river control structure flowed more than it's design capacity during the 1973 flood. That is a not my opinion, it happened. This damaged the structure, almost to the point of failure. This is not my opinon, it is published fact. You can choose to believe the sky is not blue, but that doesn't make it so.

Read page 5 of this report (page 11 of the PDF file).

http://www.lwrri.lsu.edu/downloads/L..._B12B_1980.pdf

The structure flowed 500,000 cfs instead of the designed 325,000 during the 1973 flood.

YOU ARE WRONG.

[Bandwagon King]

_ You are simply wrong. The old river control structure flowed more than it's design capacity during the 1973 flood. That is a not my opinion, it happened. This damaged the structure, almost to the point of failure. This is not my opinon, it is published fact. You can choose to believe the sky is not blue, but that doesn't make it so.

Read page 5 of this report (page 11 of the PDF file).

http://www.lwrri.lsu.edu/downloads/L..._B12B_1980.pdf

The structure flowed 500,000 cfs instead of the designed 320,000 during the 1973 flood.

YOU ARE WRONG. _

If it was flowing more than its design capacity, then the water was either going under over or around the calculated opening of the gates of the structure. I understand that you are saying that the calculated flow rates were above what it was designed to handle, however the given area of flow will only allow so much water through it. This will change slightly based upon the hydrostatic, hydraulic, or hydrodynamic head, "slightly", but once you are putting 10'X10' or 1000' X 1000' of solid fluid through a structure at a certain point you can't put anymore. That's it, cetu' fine'. I can't say I have seen the ORCS, although I have seen the power plant at Simmsport. I can say that structure is set up so that no more than a certain amount of water can flow through it no matter what. It appears as though it is about 30' thick of concrete & reenforced steel as I recall.

[CharlieK]

_ If it was flowing more than its design capacity, then the water was either going under over or around the calculated opening of the gates of the structure. I understand that you are saying that the calculated flow rates were above what it was designed to handle, however the given area of flow will only allow so much water through it. This will change slightly based upon the hydrostatic, hydraulic, or hydrodynamic head, "slightly", but once you are putting 10'X10' or 1000' X 1000' of solid fluid through a structure at a certain point you can't put anymore. That's it, cetu' fine'. I can't say I have seen the ORCS, although I have seen the power plant at Simmsport. I can say that structure is set up so that no more than a certain amount of water can flow through it no matter what. It appears as though it is about 30' thick of concrete & reenforced steel as I recall. _

Read the report, educate yourself, and stop thinking the river is a drilling rig. It is goverened by the rules of open channel flow which are different. The river has the power to make the path bigger.

And it WAS flowing more than it's capacity, it is not an IF. Again this is not my opinion it is a fact. Go ahead admit you were wrong, it will feel good.