Since the floodwaters retreated, sandy beaches have transformed more than 200 miles (320 kilometers) downstream of Glen Canyon Dam, an early measure of success. The massive floods are designed to help create beaches and back eddies for campers, rafters and native fish.
The U.S. Geological Survey recorded the canyon's transformation with remote cameras. The images shown here illustrate the variability of the flood's effects, from adding massive piles of sand to eating away at bushes and rocks.
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On the right, is an image shot at 4 p.m. on Nov. 26, 2012, from the same camera. The sandbar present in both images appears bigger after the flood.
The U.S. Geological Survey plans to measure the sand bars each October, as part of the long-term high-flow plan. "We know they all erode over the course of the next year, what we're most interested in is whether the bar in October 2013 is back to exactly the same as it was in October 2012, or if it's smaller or larger," said Paul Grams, a hydrologist with the U.S. Geological Survey's Grand Canyon Monitoring and Research Center in Flagstaff, Ariz. "It's really the long-term monitoring that is our main focus. The photos add in details of what each individual event does."
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On the right, an image captured at 9 a.m. on Nov. 29, 2012, from the camera. In it, the campsite appears to have more sand than before the flood.
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On the right, an image snapped at 12 p.m. on Nov. 27, 2012.
The flood appears to have deposited sand along the bar during the flood.
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On the right, an image shot at 10 a.m. on Nov. 28, 2012, from the camera. The beach extends farther into the river than before the flood.
Scientists plan to report initial results in January of whether the six days of high flows realized the Department of the Interior's goals of moving more than 500,000 metric tons of sediment down the canyon.
An image of the Colorado River during the flood, captured at 3:56 p.m. on Nov. 22, 2012, is in the middle.
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The high-flow release plan was announced in May by Secretary of the Interior Ken Salazar. Developed after more than 16 years of planning and testing, the strategy allows Grand Canyon flood releases on short notice, without extensive environmental review or planning, through 2020. The order calls for flows from 31,500 to 45,000 cubic feet (892 to 1,274 cubic meters) per second for up to 96 hours in March through April and October through November. Floods during the March through April period are delayed until 2015 to reduce the population of the invasive rainbow trout, which spawn in the spring, and can benefit from the floods.
On the right, an image recorded at 4 p.m. on Nov. 28, 2012, by the camera after the flood. This is Carbon camp, popular with rafters camping on the river. There is more sand at the campsite than before the flood.
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On the right, an image snapped at 1 p.m. on Nov. 25, 2012, from the same spot. The flood appears to have removed sand from part of the camp. Such variability is consistent with previous floods, Grams said.
"Some sites respond differently to the same flow," he said. "There will be certain places that tend to build big bars during the high flows, and others tend not to do too much."
An image of the Colorado River during the flood, captured at 7:28 a.m. on Nov. 22, 2012, shows the flood in progress.
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Since the dam was built in 1966, the only sediment sources for the Grand Canyon are the naturally flowing Little Colorado and Paria rivers, which feed into the Colorado River below the dam. A popular tourist destination, the canyon's beaches and wildlife depend on sand and mud carried by the Colorado River.
On the right, an image shot at 8 a.m. on Nov. 26, 2012, from the same camera. Some rocks appear more exposed than before the flood.
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On the right, an image snapped at 12 p.m. on Nov. 26, 2012, after the flood. The sandbar appears longer than before the flood.
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On the right, an image shot at 8 a.m. on Nov. 27, 2012, from the camera. The flood appears to have reshaped the sandbar, removing some sand.
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