2011 Mississippi River Spring Floods

[Turbine]

I have sympathy for anyone who experiences unfortunate/unforeseen occurrences.

At some point in time they befall us all.

If those who live and conduct business in the Basin should have known better, then they are no the only one who should have known better. Perhaps the area should have been made off limits for human habitation.

[HelmutVII]

_ http://www.mvn.usace.army.mil/bcarre/morganza.asp

Helumt, why if gates are closed did discharge rate go up? _

I read this article

http://www.2theadvocate.com/news/lat...-cut-flow.html

in the Advocate this morning saying they were passing 172K CFS. Everything I read prior to that said they were passing 114K CFS. (I always thought that that figure was kind of low. a big gate like they have up there should pass more than 6700 CFS) I went to your link and noticed the numbers didn't make sense and I figured an error was made. They closed two more today and are still passing 120K CFS. through 12 gates or 10,000 CFS per gate which is more like it.

The second page of the article gives a good explaination of how they measure velocity and get cross sections. The last two paragraphs gloss over the 1.5 Million CFS limit. If you go back to post 381 where I gave a link to Mannings equation you will see a reference to "n" in the equation. That is the roughness coefficient. The "n" for the grass on the levees is different than the "n' for the mud in the river. With the water moving faster for higher flow rates the interaction with the grass on the levees would cause a shear at the interface between the water and the levee. The river would literally tear the grass off the levees that could cause scour damage. This along with several other factors is the reason for the 1.5 million CFS limit.

[CharlieK]

_ I read this article

http://www.2theadvocate.com/news/lat...-cut-flow.html

in the Advocate this morning saying they were passing 172K CFS. Everything I read prior to that said they were passing 114K CFS. (I always thought that that figure was kind of low. a big gate like they have up there should pass more than 6700 CFS) I went to your link and noticed the numbers didn't make sense and I figured an error was made. They closed two more today and are still passing 120K CFS. through 12 gates or 10,000 CFS per gate which is more like it.

The second page of the article gives a good explaination of how they measure velocity and get cross sections. The last two paragraphs gloss over the 1.5 Million CFS limit. If you go back to post 381 where I gave a link to Mannings equation you will see a reference to "n" in the equation. That is the roughness coefficient. The "n" for the grass on the levees is different than the "n' for the mud in the river. With the water moving faster for higher flow rates the interaction with the grass on the levees would cause a shear at the interface between the water and the levee. The river would literally tear the grass off the levees that could cause scour damage. This along with several other factors is the reason for the 1.5 million CFS limit. _

Thanks helmut and jumbo.....makes sense now.

[Chop]

This is one of those subjects that I have no knowledge about.
So it would be foolish of me to take sides on who is right and who is wrong.

I know Kyle is a pretty smart guy, but I would never go against someone who does this for a living unless I really knew what I was talking about.

So im not picking sides on this.

I will say kyle's predictions on what was going to happen were pretty much 100% accurate.

But I dont have the knowledge to know if it was because Kyle knows what he is talking about or if its just a wild coincidence.


Kyle may be on to something on one hand, but on the other hand maybe not.

It may be like saying three 4th of July's ago I was popping fireworks and it started raining, so this must mean that popping fireworks causes rain. LOL

Or maybe Kyle really is onto something. I am not willing to go to school for four years to give an educated opinion on this subject.


One thing is for sure, a lot of people learned a lot info because of the questions and statements made by Kyle.

I learned a few things in this thread, but not enough to give insight on who is wrong or right.

[jumboragncajun]

One thing I have maintained throughout this discussion is that the reduction of stage level did not automatically mean reduction in flow. It possibly COULD, but other things needed to be checked before making that definitive statement. Attached to this link are hydrographs for the Stage, Velocity, and Discharge of the Vermilion River at Surrey St for the last 3 days. In this particular case, when the stage lowers, the concurrent velocity hydrograph is almost perfectly INVERSELY related. Then, it is very obvious that the velocity and Discharge Hydrographs are DIRECTLY related. So, as you can see, where the river dropped a half foot, in that EXACT TIME, the flow rate has nearly doubled. Yes, twice the amount of water flowing under the Surrey St Bridge as the river has dropped.


http://nwis.waterdata.usgs.gov/la/nw...te_no=07386880

[CharlieK]

_ This is one of those subjects that I have no knowledge about.
So it would be foolish of me to take sides on who is right and who is wrong.

I know Kyle is a pretty smart guy, but I would never go against someone who does this for a living unless I really knew what I was talking about.

So im not picking sides on this.

I will say kyle's predictions on what was going to happen were pretty much 100% accurate.

But I dont have the knowledge to know if it was because Kyle knows what he is talking about or if its just a wild coincidence.


Kyle may be on to something on one hand, but on the other hand maybe not.

It may be like saying three 4th of July's ago I was popping fireworks and it started raining, so this must mean that popping fireworks causes rain. LOL

Or maybe Kyle really is onto something. I am not willing to go to school for four years to give an educated opinion on this subject.


One thing is for sure, a lot of people learned a lot info because of the questions and statements made by Kyle.

I learned a few things in this thread, but not enough to give insight on who is wrong or right. _

BWK made a bunch of completely incorrect statements as well. If you throw enough crap against the wall some will stick.

[NewsCopy]

  The Army Corps of Engineers has closed five bays at Morganza since Tuesday as the river’s flow rate drops, corps spokeswoman Rachel Rodi said Thursday.

No bays have been closed on the Bonnet Carre Spillway because “the water is slowing down on its own,” said Rodi, although she declined to rule out the possibility of closings there.

The rest of the story

[NewsCopy]

Satellite images show large amounts of sediment throughout coastal Louisiana as a result of flooding on the ... to a request by the USGS National Wetlands Research Center in Lafayette, La. This is part of an ongoing commitment by NASA’s Applied Science ...

The rest of the story

[MC Cajun]

_ One thing I have maintained throughout this discussion is that the reduction of stage level did not automatically mean reduction in flow. It possibly COULD, but other things needed to be checked before making that definitive statement. Attached to this link are hydrographs for the Stage, Velocity, and Discharge of the Vermilion River at Surrey St for the last 3 days. In this particular case, when the stage lowers, the concurrent velocity hydrograph is almost perfectly INVERSELY related. Then, it is very obvious that the velocity and Discharge Hydrographs are DIRECTLY related. So, as you can see, where the river dropped a half foot, in that EXACT TIME, the flow rate has nearly doubled. Yes, twice the amount of water flowing under the Surrey St Bridge as the river has dropped.


http://nwis.waterdata.usgs.gov/la/nw...te_no=07386880 _

http://waterdata.usgs.gov/la/nwis/uv...te_no=07374000

http://waterdata.usgs.gov/ms/nwis/uv...te_no=07289000


http://waterdata.usgs.gov/la/nwis/uv...te_no=07381600

Wouldn't these be more relevant ?

[HelmutVII]

_ http://waterdata.usgs.gov/la/nwis/uv...te_no=07374000

http://waterdata.usgs.gov/ms/nwis/uv...te_no=07289000


http://waterdata.usgs.gov/la/nwis/uv...te_no=07381600

Wouldn't these be more relevant ? _

Yes those discharge hydrographs do tell a very interesting story I have been watching those for the last week now. I did notice that the Average discharge for the Vermilion river to be only 951 cfs with a maximum of 4650 in 2004. I would have thought that the average would be a little bit more.

I always like to use discharge hydrographs, when I can, to get a better handle on volume developed over time. They are very useful when doing retention basin design. I like hydrographs, you can get a very good picture of the situation at a glance.

If you go here

http://www.srh.noaa.gov/lmrfc/?n=lmr...oriverforecast

you will notice some plus differentials in the upper reaches of the Mississippi. I didn't think that was much - until I clicked on "Mississippi River Hydrographs" link and saw the predicted stages for a station like Cape Girardeau where they are predicting 40.5 (roughly) on June 1 or about 1.5' below a major flood stage and about 5.0 feet higher than it is today. It looks like it may be trending to an inflection point but it will take a couple of more days before we can tell. Lets hope we can keep the stages down here on a continued down trend so we can take this new bump without major problems. If things hold true to form, then this new bump should make it down here by late second or early third week in June. Only then, will we be able to be looking back at this event. Lets also hope there is not any more rain up there either and let them send it down here because we really need it.

[CajunRed]

Thanks for the update, Helmut.


igeaux.mobi

[NewsCopy]

How much water and sediment enters the area, where it ends up, and what that means to the future of the Atchafalaya Basin are questions that U.S. Geological Survey researchers at the Louisiana Water ... Research Center in Lafayette. "It'll be a cleansing ...

The rest of the story