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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."
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.
Demented But Determined.
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