Manmade Flood to Nourish Grand Canyon Ecosystem

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."

Comments

enough sediment

[peektwice]

So there's enough sediment behind the dam to be a problem, and in the process of flushing it, they also can claim to be helping the canyon's ecosystem. Not to be a pessimist, but it looks to me like they're just flushing the sediment. They've done this twice before, according to TFA.

Re:enough sediment

[E IS mC(Square)]

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

[Dr. Eggman]

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

[Dr. Eggman]

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

[Dr. Eggman]

The flood is a three-day event, and "The water level in the canyon will only rise a few feet." Water flows regularly in the area, but its a flood event when an abnormally high volume of water is released over a period of time. Think of the Nile river floods of ancient Egypt; they weren't sweeping away everything in their path, but gently raising the water levels to consume the banks, depositing sediment before receding and leaving revitalized agricultural grounds to the Egyptian farmers.

Re:enough sediment

[Tiger4]

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.

Re:enough sediment

[fredrated]

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.

And also see the other side..

[Anonymous Coward]

Not saying its all wrong, but it does not harm to consider the criticism 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:And also see the other side..

[Smordnys s'regrepsA]

" 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.

Re:And also see the other side..

[Geek Prophet]

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 time, the Colorado ("Colored") River was famous for being filled with red silt. Species of fish that evolved in this environment lived in the Canyon. Sand bars were created almost continuously due to the silt that built up. Silt replenished the shores. Moderately frequent light floods would replenish the banks near the river further, and drag more silt into the river in other areas to supply more silt for maintaining the river's muddy quality. Very occasional large floods would both replenish and clear away some of this silt, preventing the river from being clogged while "spreading around" some of the silt to places where it was thin.

Today, the Colorado river runs clear. The fish that naturally evolved there are almost wiped out. Sand bars are disappearing. The shores that used to be replenished by the river are scoured clean by the clear water. The floods that built up the flood plains don't happen any more, and there is some question as to whether big floods are good or not anymore, with a river already cleaning itself too well.

The dissenting view is that the large floods without the small floods is bad.

Small floods frequently leave the water muddy for long periods of time, much more like the natural state of the Colorado ("Colored") River, and thus protecting the fish that naturally find this to be their habitat. Small floods leave deposits that create sandbars, which are normal for the Colorado, and are disappearing in the current conditions. Small floods rebuild shoreline habitats, which evolved to have frequent small quantities of mud deposited on them. Thus "without the flood(s) the habitat will be destroyed."

Big floods run muddy for days, then run clear again. This does not help with the problem of clear water which is killing those species of fish that evolved to live in the muddy Colorado. Big floods wash away sandbars. Big floods wash away shoreline habitats. Big floods wash away archaeological treasures that are above the high water mark for small floods. Thus "the flood will destroy the habitat."

His speaking may not have been elegant, but his thinking may be better than those in favor of this flood.

Re:Don't worry about it

[AngelofDeath-02]

And of course, then there's the theory that global warming affects the ocean currents, that distribute the warm and cold climates, causing winters to be milder, and summers cooler ...

Thats why here in AZ I wore a t-shirt Clear till Mid January. Oh ya.. I'm wearing a T-shirt now, too =)

Anyway, I think its too early to dismiss global warming like you are doing. I agree that the earth is robust, but seasonal extremes is one predicted outcome of this scenario.

Re:How is this different from ....

[Dr. Eggman]

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 the regular flow takes. As you'll notice, although a larger volume of water is released in the artificial flood, the flow does not reach much farther up the sandbars than the regular flow.

Re:I have a better idea!

[Gay for Linux]

Screw civilization, it's time to go back to being hunters and gatherers. Man things were awesome then, what with all the hunting and the gathering. And the even more hunting and the gathering. And life sucking.

Re:Don't worry about it

[thestuckmud]

Nature isn't easily effected by man.

On the contrary, most biologists believe we are in the beginning of a period of primarily anthropogenic mass extinction, called the Holocene extinction event. Whether or not we choose to say this effect was achieved "easily", it is already substantial.

If they had done this earlier..

[zaunuz]

There could have been a sequel to Thelma and Louise

Challenge at Glen Canyon

[ElDuque]

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
http://www.popsci.com/scitech/article/2003-03/water-vapor-almost-busts-dam

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

Re:I have a better idea!

[wamerocity]

Great idea, except for that damn follows along the path to Lake Tahoe, and eventually to many thousands and thousands of residents of California who rely on Lake Powell to get their drinking water. I had a professor who was the president of the Glen Canyon Institute (a group that wants to drain Lake Powell and 'restore' Glen Canyon) and I've read all the arguments of why they think the dam is a bad idea, but they can never come up with a better solution on how to store all the millions of gallons of water for California as well as the 1.3 Megawatts of power it produces for many of the people in northern Arizona (especially since hydroelectric is the most 'green' source of power on the planet tied with solar power.)

Just in case..

[Rob T Firefly]

Anyone have two of every animal and several billion tons of lumber I could borrow for a while?

Was there in '96

[doooooosh]

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.

Re:Don't worry about it

[hellergood]

HA! GODWIN'S-- Oh, wait. Nevermind.

Re:I have a better idea!

[Maint_Pgmr_3]

Then where is Las Vegas going to get all of its electrical power?

hydroelectric is the most 'green' source of power

It may be green, but so Las Vegas, in the middle of no where.