After talking to several concerned readers, I decided it was way past time for me to address what is going on here with the Mississippi River flooding. And of course, I expect my very well-read readers to correct me when I am wrong; but there is a LOT of information out there to be found on this topic. By now, all of you know that Memphis has flooded, and Vicksburg is flooding, as the river crest continues to flow southward.
Granted it does feel sort of strange reporting to you like this, but I want to help you understand what we are facing. Again, information is being updated constantly, and by the time you read this, there will most likely be newer numbers to report.
The opening of the Bonnet Carre Spillway just south of Lake Pontchartrain will be completed in a couple more days to relieve the pressure off the Mississippi as she rises to flood stages along her levees. The bulk of this freshwater is running into Lake Pontchartrain, north of New Orleans, and this effort lowered the Mississippi at New Orleans by one foot last night.
This spillway is about 65 miles northeast of Bayou Dularge.
Early this evening, Governor Bobby Jindal announced the Mississippi River Commission is going to open the Morganza Spillway, located 145 miles north and slightly west of Bayou DuLarge, sometime in the next 20 hours. The town of Morganza where the spillway is located is being ordered to evacuate tonight and tomorrow morning, as the La. State Troopers are closing the roads in that town at 10 a.m. Saturday.
Here is a PDF Flood Inundation map from the Army Corps of Engineers (ACOE) that I want you to open and then put at about 50%. You won’t be able to see the whole map at once, but let’s look at the upper left quadrant first. After you open it, and get to the quadrant, I would like you to find a little town named Simmesport.
Very near Simmesport is something called the Old River Structure. At this point, about 30% of the river is redirected by this structure to flow down into the Atchafalaya River. The short version is that the Mississippi River has changed course about 7 times over a period of roughly 7000 years. That is about once every 1000 years. If this control structure were to fail, the Mississippi River would alter her course and overtake the Atchafalaya, causing serious flooding as she went.
But right now, we can’t even consider that scenario, for all eyes are on the Morganza Spillway, which you will see on the map if you scroll down a little, and look southeast of Simmesport. Morganza is right there where the yellow and green colors start. If you now scroll straight across the right, you will see the legend for what colors indicate what water heights. Now, scroll back to the left and scroll down to where you can see more of the colored areas.
You will notice that to the right, there are thinner lines of color which follow the current route of the Mississippi River. Those areas of flooding are minimal and tight to the banks. However, if you look at the Atchafalaya Basin area on the left, that is where the major flooding and inundation will take place after the Morganza Spillway is opened to just 50% capacity, allowing the river to flow through at a rate of 150 thousand feet per second.
The idea is that the Bonnet Carre spillway has taken some of the pressure off the lower Mississippi now–before the crest arrives at Baton Rouge and New Orleans. The idea behind opening the second spillway, farther north, is to divert as much of the river as the spillway structure can handle, flooding rural, bayou, marsh, and swampy areas in order to spare Baton Rouge, New Orleans, and all parts in between. That is understandable since Baton Rouge is a hub of petrochemical industry, and New Orleans is a huge shipping port.
Right now, water levels at a lock at Port Allen, on the western bank of the river just opposite Baton Rouge, are as high as they can be and still allow vessels to safely navigate the locks. If the water rises one more foot tonight, the locks will be closed to navigation, costing the economy about $1 million dollars a day. All this at a time when our economy can’t take that stab.
Someone on Face Book said it best, “Can’t Louisiana get a break?” Obviously, we cannot. Let’s go back to the map, though. Go ahead and take your time and look at and get familiar with it.
Let’s go down to the bottom two thirds in the middle of the map. Locate the large purple area, and then look for the box holding the name of my parish, TERREBONNE. Now, look just below the last “E”. That is where I live. We are in the area that stands to only get 0 – 5 feet of flooding if the Morganza is opened to 50% capacity.
The Miracle Bayou Tree House is about 12 feet above sea level, so no worry there. The slab under the house is about four feet above sea level, so we should be pretty good there, too. If we park the vehicles, riding mower, and boats on the slab, they should be fine.
Now, let’s understand why the water levels decrease as they come along. This map is a little outdated already, because last report said that Morgan City (can you find it?) is going to possibly have 20 feet of water after the Morganza is opened 50%. That water will slowly make its way into the bayous and canals and then will seep through the swamps, marshes, and backwaters making its way down here to us.
That is why we will only get 0 – 5 feet of water. This is the complete opposite of the storm surges we are used to. They come rushing in from the Gulf and just slam us. This water is going to come creeping like a silent octopus with thousands of arms reaching out to grab us. The truth is, not even the expert ACOE know what is really going to happen. They are just making educated guesses because the media vultures demand they have something to report.
Take a look at the map below. This is a newer map and the colors have changed. Our bayou community is below the city of Houma, in the color blue.
Please realize that this structure has only been used once, back in 1973, at about 30% capacity, when the river reached a volume of 1.5 million cubic feet per second. Recent reports have stated that witnesses to that opening in 1973 say the volume of water made the structure shake, tremble, and vibrate so badly the onlookers thought it would collapse. The river is flowing tonight at 1.45 million CFS, and rising. It’s time to pull the trigger, and we can only hope the antiquated spillway holds up to the pressure.
Everything I said above is the “best case scenario”. The worst case scenario, which I hesitate to even mention, is that the Old River Control Structure would give out, and there would be no end to the flooding. Or the Morganza Spillway could not handle the flow, and would fall apart, and non-stop flooding would ensue.
Below is a map of the “worst case scenario” for New Orleans–not the worst case scenario for the rural areas southwest of the Crescent City. Here is a link to the map so that you can see it in its entirety and up close.
At this point, I am not worried about our community. However, I am very concerned for all my friends that live in the areas that are going to indeed flood. I am praying that their suffering will be minimal. I have a friend whose family has a farm in the northeast part of the state where flooding has begun. They have corn and cotton in the fields they cannot harvest and 1000 head of cattle that they will not be able to evacuate. These are the folks who need our prayers.
As the water gets closer, I hope to be able to keep you up to date.
Please feel free to ask questions, and I will answer them to the best of my ability, and if I can’t, one of the other readers will be able to do so. Thank you all so very much for your care and concern about our bayou communities. God knows we have had our share of catastrophe and it would be nice to “catch a break” for a change.
It is now just a game of wait and see.