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wcerto
Ahonui
USA
5052 Posts |
 Posted - 03/08/2008 : 01:25:52 AM
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Try read this. What do you think about this? Is it a proper attempt to right something that man has screwed up? Could there be ulterior motives? If this needs to be done, why they don't do it every year?
Manmade Flood Unleashed in Grand Canyon
By AMANDA LEE MYERS – 2 days ago
PAGE, Ariz. (AP) — Four arcs of water unleashed from a dam coursed through the Grand Canyon on Wednesday in a flood meant to mimic the natural ones that used to nourish the ecosystem by spreading sediment.
More than 300,000 gallons of water per second were released from Lake Powell above the dam near the Arizona-Utah border. That's enough water to fill the Empire State Building in 20 minutes, said Interior Secretary Dirk Kempthorne.
"This gives you a glimpse of what nature has been doing for millions of years, cutting through and creating this magnificent canyon," Kempthorne said after he pulled the lever releasing the water from Glen Canyon Dam, upstream from Grand Canyon National Park.
The water gushed from two of four giant steel tubes in parallel arcs into the Colorado River. By afternoon, water poured from all four tubes, creating a churning pool beneath the sheer, sandstone canyon walls rising hundreds of feet.
The water level in the Grand Canyon rose 2 to 15 feet in some places. After the flood ends Friday, officials hope the water will leave behind sediment and restore sandbars as it goes back to normal levels. Officials have flooded the canyon twice before, in 1996 and 2004.
Before the dam was built in 1963, the river was warm and muddy, and natural flooding built up sandbars that are essential to native plant and fish species. The river is now cool and clear, its sediment blocked by the dam.
The change helped speed the extinction of four fish species and push two others, including the endangered humpback chub, near the edge.
Shrinking beaches have led to the loss of half the camping sites in the canyon in the past decade. Since Glen Canyon Dam was built, 98 percent of the sediment carried by the Colorado River has been lost, Grand Canyon National Park Superintendent Steve Martin said.
Martin said manmade floods need to occur every time there's enough sediment to do so — about every one to two years depending on Arizona's volatile monsoon season.
"The science is really clear that's what we need to do," Martin said.
The Grand Canyon Trust, a Flagstaff-based group that has been critical of the federal Bureau of Reclamation's management of the dam, also is calling for more regular high flows.
"The power industry is driving the Bureau of Reclamation more than anything else, as opposed as to what's best for the canyon," trust spokesman Richard Mayol said.
Scientists will document habitat changes and determine how backwater habitats are used by the chub and other fish. Another study will look at how higher water flows affect the aquatic food base.
On the Net:
Grand Canyon National Park: http://www.nps.gov/grca
Bureau of Reclamation: http://www.usbr.gov
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Me ke aloha
Malama pono,
Wanda |
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ypochris
Lokahi
USA
398 Posts |
Posted - 03/08/2008 : 03:28:52 AM
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They are doing this because they are forced to by environmental and tour groups- the value of that water for electrical generation and agriculture is substantial. Normally none of the water from the Colorado river reaches the ocean, and the lack of nutrients and fresh water has destroyed what was, when I was a kid, the richest fishery in the world. But that is in Mexico, so who cares?
I remember as a child, after the dam was built, driving over a mile wide bridge over the Colorado river just above the border- and not a drop of water underneath. I understand that some water is now allowed to flow to farmers in Mexico, but nothing is left to make the connection between the sea and the upper river. Annual flooding would be very helpful from an environmental standpoint, both for the river and for the Sea of Cortez, but it is only done when a "surplus" is anticipated. Frankly some fraction of the normal flow should be allowed to reach the sea every day of the year, not three times in 45 years, but it "ain't gonna happen".
Chris
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Kapila Kane
Ha`aha`a
USA
1051 Posts |
Posted - 03/13/2008 : 12:15:09 PM
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I remember, it seems, that the first one of these heavy flow releases (in the 90's?) was necessitated by heavy run-off, Spring Storms, and (at that time) the relatively newly "discovered" El Nino dumping lots of spring snow here in Colorado.
And the benefit to the Canyon was an extra...some had predicted the gain in sandy beaches and positive habitat change...
But I don't think the first one could have happened without some intervention from the Clouds!
I'm glad to see it, what being friends with a few Colorado Rivers enthusiasts, as well claiming to be an environmental guy.
Is there live web or you-tube footage of the current high flows? Didn't see a live or recent video link on the National Park site.
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Edited by - Kapila Kane on 03/14/2008 08:04:53 AM |
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wcerto
Ahonui
USA
5052 Posts |
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kawikasurf
Aloha
USA
28 Posts |
Posted - 03/14/2008 : 08:14:46 AM
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| When they did this before, sandbars returned and riverine vegetation reestablished itself nicely upon them. Over time - a relatively short time - the sandbars eroded again and things returned pretty much to normal (i.e. abnormal). From what I've heard, in both instances, the results were fairly dramatic and uniformly positive. |
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