How the Mississippi River levees could fail
A levee near Tomato, Arkansas, is typical of those that line the sides of the Mississippi River. They can fail in several ways.
May 9th, 2011
09:14 PM ET

How the Mississippi River levees could fail

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Pictures can't describe the misery playing out along the Mississippi River for those unprotected by flood levees and walls. Some homes, farms and businesses will be 25 feet underwater for weeks until the water recedes.

The river is still rising from Memphis, Tennessee, to the south. In Memphis, where the river is expected to crest at a near-record 14 feet above flood stage on Tuesday morning, the water was moving at 2 million cubic feet per second on Monday. At that speed, water would fill a football field at a depth of 44 feet, according to the Army Corps of Engineers.

Earthen levees should keep most of the larger towns and cities safe as an extraordinarily high volume of water runs down the Mississippi to the Gulf of Mexico. But levees can fail, in part because moving water has tremendous force. This force will try to erode, saturate, undermine and destroy everything in the way.

Most levees are piles of dirt lined along edges of a river. In theory, vegetation and its roots will keep the dirt stable as water flows by.

Levees can fail if water runs over the top – this is called overtopping. The force of the moving water erodes the soil below, and this can cause a catastrophic breach. The erosion continues until the hole is so large that floodwaters surge into the now unprotected land.

Levees also can fail from below as the water pressure undermines the piled dirt. The water forces itself below the levee and eventually out from the bottom on the dry side of the pile. This is called a sand boil or a mud boil, because of its bubbling appearance.

Also, too many days with floodwater near the top of a levee can saturate the levee’s soil, causing a washout and breach.

The Army Corps of Engineers will be watching for signs of these potential levee failures and will try to take corrective action if it sees them.

"There's always some seepage to be expected generally in the earthen levee systems, and you manage the process by inspecting it, (looking) for the seepage, and (making) sure wherever you find it, you control it,"
retired Army Corps of Engineers Maj. Gen. Thomas Sands said on Monday.

Record or near-record crests are forecast into next week. Sands said that although this month's levels are remarkably high, the levee system has held back high water before.

"The level of degree of confidence in the levee system is basically borne based on the fact that it’s performed so reliably in the past," Sands said.


Army Corps battles rising Mississippi from Memphis to New Orleans

- Epic flooding will test levee system as never before, experts say

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Filed under: Arkansas • Louisiana • Mississippi • Tennessee • Weather
soundoff (73 Responses)
  1. Jones

    I sTrongly agree!!! whats wrong with you people...there is no judgement will die when your old and gray...thats your judgement day thats how its been and thats how its gonna be....

    May 10, 2011 at 12:39 pm | Report abuse |
  2. Jones


    May 10, 2011 at 12:42 pm | Report abuse |
  3. Mmmmm

    The Mighty Mississippi!

    May 10, 2011 at 5:50 pm | Report abuse |
  4. RealTime

    Another way that levees fail is when government bureaucrats blow them up.

    May 10, 2011 at 6:38 pm | Report abuse |
    • Vicki

      Yes, blowing them up is the answer to saving one town in ILL is the way we save lives to destory farmland and cause Americans to pay higher taxes. The American people are finding out that goverment bureacrats know what is better for the American people destory a levee to save a town. I am sure we will be dealing for years for this mistake which can not ever be reverse. I hope that the American People realise that blowing up a levee was the only thing they had Left to do which is the question was it worth it?Destory to save is the new slogan for the American people..

      May 11, 2011 at 9:04 am | Report abuse |
    • Hasher Iva

      I guess I'm missing something. 130,000 acres of farmland was flooded to save a town of 2,500. I don't have the numbers to do cost-benefit analysis, but I'm betting that 130,000 acres of farmland and the buildings and equipment on it are cheaper than the town.

      In my civics and history classes it was always talked about how the flooding of the Mississippi, while disruptive was also very vital to the life of the river and downriver. Washing out the river and depositing a layer of nutrient rich silt on the farmlands was critical to survivability. Now suddenly a silt deposit is a disaster and it will take 20 years to recover. Who came up with that analysis? Compared to arable farmland, how much is 130,000 acres? A few tenths of one percent?

      Come on folks, look at the big picture. Sure, it's going to be very inconvenient for the folks in that 130,000 acres and I'm sure the USG will spend money it doesn't have to help them recover, but in the grand scheme of life, the US and survival which is the least burdensome?

      May 11, 2011 at 12:57 pm | Report abuse |
    • Beaux

      Yes I'm sure that you thought about and analyzed it more than the people whose job it is to do.

      May 12, 2011 at 1:54 pm | Report abuse |
    • wzrd1

      Astonishing that you are so ill read that ALL you can think of is one town, NOT THE REST OF THE LEVEES.
      THAT was the reason that the levee was breached, the SECOND breach that week, one other being in Tennessee.
      But, you cry that about 220 farms got flooded, you'd rather THE ENTIRE REGION flood!
      You'd prefer catastrophic levee failures that cascade down, killing hundreds of thousands of people!
      How about you STFU and let the professionals handle this, YOU are not a civil engineer. Indeed, what IS your experience in such engineering, other than flipping burgers and denigrating the highly skilled men and women of the US Army Corps of Engineers?

      May 15, 2011 at 2:24 pm | Report abuse |
    • Army Corp of Failures

      The Army Corp of Engineers are no geniuses. This was especially evident last year in Nashville when they opened a dam WIDE OPEN and caused a lot of the flooding that would not have occurred otherwise. Add to that their failure to watch a simple weather report which predicted how much rain was supposed to fall and they could have opened the dam prior to the rains.

      May 15, 2011 at 3:56 pm | Report abuse |
  5. Taylor

    I live here in New Orleans. My main concern is them opening the morganza spill way.. But i know people who live in the morganza spill way. And then comes the thought of our levees breaking. Should we be worried about our levee breaking or will we have a warning?

    May 11, 2011 at 2:19 pm | Report abuse |
    • wzrd1

      The Corps of Engineers are out, monitoring the levees. Local authorities are monitoring them as well, you KNOW that, after all, THEY would get flooded too!
      So, yes, you should get warning before any failure.

      May 15, 2011 at 2:27 pm | Report abuse |
  6. Justy

    Speaking from experience, the worst case is an over run (they called it overtopping in this article.) Simply put if the water starts coming over a levee, run, you don't have long before the sucker is gone. Boiling is pretty rare, at least here in Tennessee, can't say that I've ever seen a lot of boiling levees. Washouts happen but usually someone from ACE is there to fill it with sand or rock. Washouts from what I've seen are slower than over runs. Biggest fear anyone has especially with dams and levees are when water starts covering what's protecting you.

    May 11, 2011 at 3:25 pm | Report abuse |
  7. ron

    old black water keep on rollin, missisippi moon keep on shining on me.

    they should never have built levees.
    They should have left the river banks alone and built thier homes on stilts. this way if the river flooded no big deal it raises a few feet and disappates.

    now with all the levees the water gets up what 30-50 feet and when it breaks I cant help but hear led zepplin jammin in the background.

    When the levee breaks... When the levee breaks Ill have no place to stay.

    ~Cryin wont help you, prayin wont do you no good,(<- cause there aint no god)
    Now, cryin wont help you, prayin wont do you no good,( <- im serious... just ask jesus to stop the flood. lol)
    When the levee breaks, mama, you got to move. ( i reccomend higher elevation out of flood zones.)

    Very true words.

    peace yall

    May 11, 2011 at 4:47 pm | Report abuse |
    • wzrd1

      Take your medication. You missed a dose.

      May 15, 2011 at 2:28 pm | Report abuse |
  8. joe

    for the latest breaking news on the mississippi flood go to,

    May 12, 2011 at 2:34 pm | Report abuse |
  9. hannah dav

    May 14, 2011 at 6:40 pm | Report abuse |
  10. Observer1290

    Obama is either a liar or insane.

    May 30, 2011 at 1:14 pm | Report abuse |
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