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Science

Manmade Flood to Nourish Grand Canyon Ecosystem 56

Posted by samzenpus from the two-of-every-kind-of-tourist dept.
Dr. Eggman writes "The Associated Press brings us news of a flood in the Grand Canyon. This flood is no ordinary flood, however. This is a man-made flood released from the Glen Canyon Dam. The Dam is releasing four to five times its normal amount of water over the course of a three day artificial flood. Scientists are conducting this massive experiment in order to document and better understand the complex relation of the aquatic habitats, natural floods, and the sediment they bring. Floods no longer bring sediment to these parts of the canyon as the Dam keeps it locked up and released in small, drawn out intervals. The Dam prevents the floods from bringing the sediments in to replenish the sandbars and allow the river to maintain its warm, murky habitat rather than a cool, clear one. It is thought that this cool clear environment brought on by the dam is responsible for helping to extinguish 4 species of fish and push 2 more towards the brink. It is hoped that this terra-reformation experiment will positively impact the habitat and fish populations, warranting further artificial floods at an increased rate of every one to two years rather than the time span between the two previous floods and this one of 8 and 4 years."
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Manmade Flood to Nourish Grand Canyon Ecosystem More

Manmade Flood to Nourish Grand Canyon Ecosystem

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  • Comment removed (Score:5, Informative)

    by account_deleted ( 4530225 ) on Wednesday March 05, 2008 @09:12PM (#22658540)
    Comment removed based on user account deletion
    • Comment removed based on user account deletion

    • Re: (Score:3, Insightful)

      by E IS mC(Square) ( 721736 )
      Mod parent up. If they really want to 'restore' the earlier eco-system, the dam should be removed. How can effect of years of flow be achieved with one or two 'manmade' floods?

      • Re:enough sediment (Score:5, Insightful)

        by Dr. Eggman ( 932300 ) on Wednesday March 05, 2008 @09:51PM (#22658848)
        The natural state of the river did not, according to theory, see the average flow building up sediment, but rather from the sound of the article swept away more sediment than it deposited. It was the natural flooding of the Arizona monsoon seasons that deposited enough sediment to replenish the habitat, often enough to prevent species populations from collapsing. The artificial floods are meant to mimic those flood, every one to two YEARS (if the practice proves beneficial then on a continuing basis) and restore the habitats to a state similar to before the Dam. Removing the Dam is out of the question. Frankly, I'd be happy they're concerned enough to warrant the possibility of making this an annual event; considering the last two times this flooding occured just to flush out the sediment were in 1996 and 2004. 8 years and 4 years before they need to dump sediment for the Dam's sake, but purpose every year or two years for the environment's sake.

        • Re:enough sediment (Score:5, Informative)

          by fredrated ( 639554 ) on Thursday March 06, 2008 @10:29AM (#22663278) Journal
          The 'average' flow either deposited or removed sediment, depending on the amount of sediment already present when the flow occured. The Colorado River was named 'red' for a reason: it always carried a huge sediment load which it had picked up along the whole length of its run from the rocky mountains. The canyon and the river were in dynamic equilibrium: if the river was a little under in it's sediment load it would scour some from the canyon; if it had a little more than usual it would deposit sediment. The reason the Arizona monsoon has come to play a dominent role is because almost all of the pre-canyon sediment load is deposited at the head of lake Powell now, so now the only significant sediment is what is deposited by the Paria, the Little Colorado and other side canyons below the dam, when they flood during the monsoon. And that amount is pathetically small compared to what the river carried in the pre-dam period.

          The Arizona monsoon floods were not necessary to keep species from collapsing, the river always had a huge sediment load that was inimical to species like trout that need clear water. Thus there was basically no competition for habitat until Glen Canyon Dam turned the water clear. All that the artifical floods do is churn up the 'monsoon' deposited sediment from the bottom and move it up onto the existing and previously existing beach sites, benificial for plant and animal habitat. It does nothing for the hump-back chub because in very short order the water will run clear again. And the previous 2 floods have demonstrated that these newly deposited beach sands do not stay long. As long as the Colorado River through Grand Canyon runs clear it will scour and carry away sediment to Lake Meade.

          I am not sure what you mean in the sentence fragment "...before they need to dump sediment for the Dam's sake...", but no sediment is being removed from behind the dam. In fact, geologists estimate that it will probably be only a couple of hundred years before lake Powell is full of sediment and the dam will become a waterfall. The waterfall will then undercut the damn pretty quickly, as it has undercut lava flows in the past, and the dam will be gone.

          As for the articles comment that half the camp sites in the canyon are disappearing, this only refers to camp sites used by river runners. If you backpack in the canyon back country, the best place to go, you will find an unlimited number of camp sites.
      • Glen Canyon Dam's Life expectancy was 75 yrs, and was completed in the 60's. Why 75yrs? That's the rate that the sediment is filling up behind the dam.

        Been there, done that...

    • Re: (Score:3, Informative)

      by Dr. Eggman ( 932300 )
      Don't know if I should reiterate this or not, but the last dump was in 2004 and the one before that was 1996. It hardly seems as though they need to dump sediment again for the Dam's sake after 4 years if the previous dump span was 8 years. Furthermore, the article proposes the possibility of annual or biannual dumps, if the restoration attempt proves beneficial to the fish habitats.

    • Re:enough sediment (Score:4, Insightful)

      by Tiger4 ( 840741 ) on Wednesday March 05, 2008 @10:17PM (#22659080)
      Are they really flushing the sediment behind the dam, or just eroding the banks near the floodgates to redeposit it further downstream?

      I realize that some sediment will leave the dam. But, really most sediment from upstream drops out of the flow when the water slows as it enters Lake Powell. The sediment near the dam has been there for years, since the dam was new and the lake first filled. If you look at the released water, it is significantly clearer than the muddy stuff entering the lake upstream.

    • It looks to me like the question isn't IF they do this (they already do on a regular schedule) but the frequency.

      So perhaps they really are just trying to do the right thing?

  • And also see the other side.. (Score:2, Informative)

    by Anonymous Coward
    Not saying its all wrong, but it does not harm to consider the criticism [nytimes.com] as well.

    " Far from restoring crucial sand banks and other areas, the flows could destroy habitat, [Grand Canyon National Park Supt. Steve Martin] said. One flood was not enough, Martin said Monday. Holding off follow-up flows for months would leave endangered humpback chub fish, sandbars used by river rafting trips, and archaeological treasures at river's edge diminished "almost to the point of no return," he said."

    • Re: (Score:3, Insightful)

      by Smordnys s'regrepsA ( 1160895 )

      " Far from restoring crucial sand banks and other areas, the flows could destroy habitat, [Grand Canyon National Park Supt. Steve Martin] said. One flood was not enough, Martin said Monday. Holding off follow-up flows for months would leave endangered humpback chub fish, sandbars used by river rafting trips, and archaeological treasures at river's edge diminished "almost to the point of no return," he said."

      Those habitats survived thousands of years of flooding before we created the dam, what makes him think a single flood would destroy it? And, why does he say both that the flood will destroy the habitat and that without the flood the habitat will be destroyed? Superintendent, yes. Elegant speaker/thinker and specialist, I think not.

      • Those habitats survived thousands of years of flooding before we created the dam, what makes him think a single flood would destroy it? And, why does he say both that the flood will destroy the habitat and that without the flood the habitat will be destroyed? Superintendent, yes. Elegant speaker/thinker and specialist, I think not.

        Of course, there are probably 1800 or so different theories as to what will happen which just goes to show that the pursuit of science and truth is alive and well (also that at

      • Re: (Score:2, Insightful)

        by Geek Prophet ( 976927 )

        Those habitats survived thousands of years of flooding before we created the dam, what makes him think a single flood would destroy it?

        He doesn't think the one flood will destroy it. He thinks the one flood could excessive damage. This is in part because the canyon's habitat is already damaged, and thus vulnerable. In addition, this is a large flood, and large floods are often more damaging than beneficial.

        And, why does he say both that the flood will destroy the habitat and that without the flood the habitat will be destroyed?

        He didn't say that the flood would both destroy and prevent the destruction of habitats. He said that floods, plural, on a regular basis would build up habitats, and that one big flood every year or two would destroy them.

        Once upon a t

  • Irrigation?!

    Usually, it is a small area that gets a small amount of water 'inserted' by man... but this is a big area, so ... isn't it just irrigation on a large scale?

    • Re: (Score:3, Informative)

      by Dr. Eggman ( 932300 )
      Its not so much about the volumes of water we are trying to bring downstream, in fact the Dam does regularly release water downstream (hence its function as a dam and not a reservoir barricade.) Instead, its about the material brought along with the water flow. The amount of sediment deposited by the regular flow is not enough to offset the sediment swept from the sandbars and it is hoped that periodical flood volumes of water would deposit much more sediment, enough to offset that which it takes as well as

      • Re: (Score:2)

        by afidel ( 530433 )
        Actually the story I read the other day said that a primary aim was to remove sediment from the bottom to open up rocky spawning pools that have been filled with sediment.

  • If they had done this earlier.. (Score:3, Funny)

    by zaunuz ( 624853 ) on Wednesday March 05, 2008 @11:28PM (#22659592)
    There could have been a sequel to Thelma and Louise
  • Anyone else read this as "Manmade Food to Nourish Grand Canyon" and automatically think of that famous Charlton Heston movie?
     

    • Re: (Score:2)

      by cgenman ( 325138 )
      I actually read this as "Marmalade Flood." ...which proves that the biggest hole on earth is still British.

  • Challenge at Glen Canyon (Score:5, Interesting)

    by ElDuque ( 267493 ) <adw5@lehigh . e du> on Thursday March 06, 2008 @12:12AM (#22659882)
    The Glen Canyon Dam was almost the site of a much larger flood in 1983, when it was nearly overtopped.

    http://www.google.com/search?source=ig&hl=en&rlz=&q=%22the+1983+flood+at+glen+canyon%22&btnG=Google+Search [google.com]
    http://www.popsci.com/scitech/article/2003-03/water-vapor-almost-busts-dam [popsci.com]

    The cavitation damage to the solid rock of the spillway walls was truly incredible.

    For an exciting telling of the story, search Google Video for "Challenge at Glen Canyon". (You will be instantly reminded of every National Parks visitors center you have been in.)

    http://video.google.com/videoplay?docid=-1358563539762136744 [google.com]

  • I misread the title as "Marmite Flood to Nourish Grand Canyon Ecosystem", and started wondering whether the ecosystem would love it or hate it.

  • Just in case.. (Score:3, Funny)

    by Rob T Firefly ( 844560 ) on Thursday March 06, 2008 @09:15AM (#22662472) Homepage Journal
    Anyone have two of every animal and several billion tons of lumber I could borrow for a while?

  • Was there in '96 (Score:3, Interesting)

    by doooooosh ( 1124823 ) on Thursday March 06, 2008 @10:41AM (#22663408)
    Went on a ten day backpack through a portion of the canyon just after they did this in 1996. I've traveled extensively since then all over the world, and that trip stands out as one of the most amazing I've ever been on. The sandbars that the floods left behind were the size of football fields in places, and as our group was the first to come through after the flooding, they were untouched. (Though the muddied river was hell on our water filters). Anyone who has the opportunity really should take a trip through the canyon at some point (how I envied the rafters who would float effortlessly by!); it's truly an awe inspiring trip.
    • Hey, were you on the GCFI Grand Canyon Supergroup hike, 10 days Nankoweap to Bright Angle? Just a week or so after the '96 flood? If so then I was a fellow hiker! That hike was so awsome, I shudder to think of how hard it was.
      • That was definitely the timeframe, but a different group. I wish I could come up with the exact route. I think it was from Grandview to South Kaibab? I can't be sure. The first day, 10 miles of hiking through the desert to the river nearly killed me.
  • Why not install some sort of churning device near the dam, to stir up the sediment so it ALWAYS flows through the dam, thus achieving something closer to the natural pattern year-round??

    • Re: (Score:1)

      by k8to ( 9046 )
      I suspect this would not be popular because the dam is supossed to generate power. I haven't considered the relative amount produced and required.

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