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SELAWIK: Research Continues on Continent’s Largest “Thaw Slump”
Alaska Region, September 25, 2009
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A 2009 aerial view of the Selawik River thaw slump, the largest of its kind known in North America.
A 2009 aerial view of the Selawik River thaw slump, the largest of its kind known in North America. - Photo Credit: n/a

In 2004, a large permafrost thaw slump (or “mudslide” in common language) occurred on the upper Selawik River in the Selawik National Wildlife Refuge in northwest Alaska. Since that time the slump has transformed the once clear river into a turbid one for more than 80 downstream river miles. Critical spawning habitat for sheefish—a large whitefish prized by subsistence and sport fishermen—lies 25 miles downriver from the slump, generating concern that the heavy sediment might interfere with successful spawning and egg survival.   

Two research projects took place this summer to continue investigating and documenting this 9-acre thaw slump, the largest of its kind known in North America. One study, led by Dr. Benjamin Crosby of Idaho State University, quantified the slump’s growth and sediment production using water quality sensors and remote interval photography among its techniques. A second study, headed by Chris Zimmerman of USGS, mapped sheefish spawning activity, egg settlement patterns, and substrate characteristics to develop a model comparing settlement patterns of eggs and fine sediments. Both projects are expected to continue in subsequent years.

In the past 50 years, Alaska has warmed at more than twice the rate of the rest of the United States’ average. These higher temperatures contribute to permafrost warming, which can create dramatic changes in both hillslope stability and river dynamics. Scientists at this point see no end to the Selawik River slump. Thaw activity of this sort has occurred in the Arctic for thousands of years, but its frequency is increasing. For this reason, it is critical to gain a better understanding of the impacts of thawing permafrost on human and natural systems. Stay tuned for future research updates!


Contact Info: Susan Georgette, 907-442-3799 ext 16, susan_georgette@fws.gov



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