Canadian river vanishes in 4 days
Scientists have witnessed the first modern case of what they call "river piracy" and they blame global warming. Most of the water gushing from a large glacier in northwest Canada last year suddenly switched from one river to another.
That changed the Slims River from a 10-foot (3 meters) deep, raging river to something so shallow that it barely was above a scientist's high top sneakers at midstream. The melt from the Yukon's Kaskawulsh glacier now flows mostly into the Alsek River and ends up in the Pacific Ocean instead of the Arctic's Bering Sea.
It seemed to all happen over a period of four days from 26 to 29 May last year based on river gauge data, said Dan Shugar, a University of Washington Tacoma professor. A 100-foot (30-meter) tall canyon formed at the end of the glacier, rerouting the melting water, Shugar and his colleagues wrote in a study published in Monday's journal Nature Geoscience.
The scientists had been to the edge of the Kaskawulsh glacier in 2013. Then the Slims River was "swift, cold and deep" and flowing fast enough that it could be dangerous to wade through, Shugar said. They returned last year to find the river shallow and as still as a lake, while the Alsek, was deeper and flowing faster.
"We were really surprised when we got there and there was basically no water in the river," Shugar said of the Slims. "We could walk across it and we wouldn't get our shirts wet. It was like a snake-shaped lake rather than a river."
The lack of water in the Slims wasn't because of changes in rainfall, Shugar said. They know that because it's a river fed mostly by glacial melt, not rain, and the Alsek increased in amounts similar to what disappeared from the Slims.
The Kaskawulsh glacier covers about 9,650 square miles (25,000 square kilometers), about the size of Vermont. The front of the glacier has retreated nearly 1.2 miles (1.9 kilometers) since 1899, Shugar said.
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