Modeling Drainage on the Kuskulana Glacier
Up close and personal with “chaotic surface topography.” Photo courtesy of Ryan Strickland.
By Allison Sayer
Ryan Strickland is a third year PhD student at the University of Arkansas studying glaciers. He recently turned his attention to the Kuskulana Glacier, hoping it could help him create models to better understand glacial outwash flooding. He travelled there with his advisor Dr. Matt Covington from August 21 through September 5 of this year.
McCarthy area residents are familiar with the generally annual jökulhlaup, or outwash flood, that creates flood conditions on the Kennicott River. Hidden Lake, held back for much of the summer by an ice dam, drains into the river at a catastrophic pace, leaving behind an empty basin. Locals and tourists gather at the footbridge to watch enormous icebergs cruise downstream, and to cheer on whitewater boaters enjoying the temporarily massive waves.
In the Himalaya, however, Strickland explained, an outwash flood is no party. Human lives and infrastructure can be destroyed in an instant, even hundreds of miles downstream. The floods are not typically annual, he said. Instead, a “lake builds up over decades, causing unexpected, rare, massive floods.” He added that this cycle has been going on for millenia, “the big floods are a big part of why the river channels look the way they do."
Why the Kuskulana? Looking at satellite imagery, Strickland found that the surface of the Kuskulana looked similar to the Ngozumpa Glacier and the Khumbu Glacier, which he had the opportunity to study in Nepal, and from which flooding could be devastating to downstream communities. Like them, it is “debris covered,” meaning much of the surface is covered with rock and dirt. It also has the same “chaotic surface topography.” Strickland is interested in “how drainage processes both shape that topography and are influenced by it.”
He continued, “The problem with studying that in the Himalaya is the glaciers are shorter but wider, and they have a lot more debris. To understand how the topography develops and influences drainage you need to go high on the glacier where the topography has just started.” He continued, “The elevation creates logistical problems. It’s hard to work there, not near any of the infrastructure, and just the access itself may be impossible.” He also wanted the ability to fund his own dissertation research, and accessing the Kuskulana is much less expensive because you can walk there.
Strickland hopes extremely detailed surface exploration and photography can help model and predict both the origin and drainage results of surface water features.
Strickland examined two general types of drainage structure: melting from above and melting from below. From above, solar radiation melts ice faster where it is less insulated by debris, creating a depression. This leads to a bowl that traps meltwater and expands into a pond, or eventually a surface river.
From below, a “sinkhole” can form, eventually creating cracks and openings which funnel water to the sinkhole below the surface, which also melts more ice. “We definitely observed both,” said Strickland. “I wanted to look at the morphology of those structures.”
Exploring a glacial drainage feature. Photo courtesy of Ryan Strickland.
There are several reasons it’s important to distinguish drainage types on the glacier, said Strickland, “Water entering the glacier and getting into the bed influences how fast it moves. Water stored on the surface is not getting to the terminus or the rivers.” Also, “When you have water stored on the surface it creates ice cliffs that melt really fast and make the pond grow. How the water is draining and how it’s stored are important components of how it melts.”
Strickland and Covington spent several days documenting surface drainage structures, exploring the surface and using a handheld GPS. They were looking at moulins, caves, and what looked like abandoned moulins. Strickland is “hoping we can see spatially where these features are appearing and where they may have appeared based on the rate of glacier motion. That’s typically done with repeat imagery.” He hopes to compare images between years, looking at clearly identifiable features, although cloudy conditions may make that challenging.
Ryan Strickland documents surface water surrounded by debris. Photo by Matt Covington.
Strickland continued, “After we had explored and documented a number of these features I took hundreds of pictures of individual ones from a bunch of angles so I could make 3D models.” The goal is to, “with a high level of precision, quantify shapes and get a better way to identify which structures are draining in-glacially and which are not.” This process is called “structure from motion photogrammetry.” Strickland explained, “This is a common method used to study debris covered glaciers and landscape change in general...The USGS maps that we were looking at had 50 foot contours. We’ll get less than 10 cm accuracy, every little curve.”
This winter, Strickland will compare the fine structure of features he could observe were draining in-glacially and compare them with those that were not. He hopes to find a “feature in the topography that distinguishes the two.” Can these features then be detected on high resolution aerial maps, scaling up to create a larger scale picture of glacial drainage? Strickland hopes so. There is a lot of detailed computer and mathematical work in Strickland’s future. I hope to catch up with him next year to learn more about his results.
I wanted to learn more about Strickland and Covington’s trip. It started with wandering around Chitina until he found someone who could pick them up when their journey was over. “Nobody was in the hotel,” he said, “I ran into the art gallery and there was a man named Mike working the desk. I said, ‘Mike, we are about to be on the Kuskulana Glacier for 15 days and we need a pick up in the end. Do you know somebody?’” Mike of course agreed to retrieve the two scientists. To put blind faith in a stranger to pick you up in the middle of nowhere, on the basis of a handshake, when you were likely to be out of food and certain to be exhausted only meant one thing: These guys had the personality for a successful expedition in the Wrangells.
For gear, Strickland and Covington carried camping and camera equipment along with microspikes and helmets. They walked up the Nugget Creek trail and “skirted up the west side, following a tributary of the Kuskulana. It emanates from a giant cave. That gets you access to the main glacier and then we walked up glacier from there.” They were both blown away by the “spectacular beauty” of the Wrangells.
Once on the glacier, Strickland said, “Getting around and across the glacier was a serious challenge. We’re both pretty fit and used to this sort of travel. With our 75 pound packs and the route finding, we couldn't do better than about a half mile an hour. It took us 8 or 9 hours to get across.”
Covington and Strickland high on the Kuskulana Glacier. Not pictured: Rain.
Photo courtesy of Ryan Strickland.
For much of the trip, the two “basecamped up in a beautiful hanging valley on the south side of the glacier. “We found Dall sheep skeletons, skulls and horns, and an old food cache I suspect was an airdrop a long time ago; the remnants of a parachute and dented out, rusted out cans. One had 20 lbs of coffee, at least that was what was labelled. I have no idea what was going on up there, but that food drop didn’t work out; those cans were destroyed.”
For the imagery portion of the trip, the two spent three nights bivvied under a tarp high on the glacier, at the confluence of glaciers coming from Mt. Blackburn and Castle Peak. “Castle Peak was dropping avalanches all day, multiple times an hour,” he said, “We would watch it in the evenings- massive slabs of ice and snow dropping 500 feet... I’m always ranking my most spectacular sleeping places, and this was probably the top one or two.”
Another highlight for Strickland was exploring caves towards the end of the trip. “We found a number of impressive caves that were safe enough to walk into. One was a marvelous passage, maybe 10 yards wide and 6-20 feet tall, with structures on the wall that you see normally in caves but made of water.” They donned helmets to enter the caves, a precaution against rockfall, particularly at the mouth. He said the way to enter is to observe first, “watch where they’re falling, put on the helmet, and then run in.”
The two did get to experience some of the Wrangell Mountains sufferfest that all adventurers endure. Although they had good weather at their high camp, “Most of our exploration days were in rain or intermittent rain. A lot of time being wet and a lot of effort keeping our stuff dry back at camp, particularly our sleeping bags. I had a bit of a leaky tent issue. Our boots were falling apart, particularly mine. I had what I thought were a great pair of boots that were not designed for the amount of abuse.” By the end, they were “tied together with paracord and partially sewn together with a speedy stitcher.” Still, Strickland says he and Covington are “already talking about our next trip.”
Strickland’s research is funded by a Geological Society of America (GAS) Graduate Student Research Grant and the Department of Geosciences at the University of Arkansas. You can read about a related project in the Himalaya at: https://www.nytimes.com/2021/09/13/travel/glacier-caves.html.
More Copper River Record coverage of research in the Wrangells:
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