Thinking Like a Fish: Navigating Arctic Streamflow Change

This story is Part II of a two-part series on the Tanana River Watershed. See Part I here.

Melt from Alaska Range glaciers feeds lowland rivers through the year (Source: Salcha-Delta Soil and Water Conservation District).

Long-term monitoring has consistently shown that winter flow levels in Interior Alaska rivers are rising. But why? Precipitation is not systematically increasing, and most source waters are frozen in winter. According to a new paper in Geophysical Research Letters, the answer comes from far away: as mountain glaciers melt during the summer, melt water percolates into aquifers and later resurfaces downstream, making streams flow fuller in the coldest months.

For University of Alaska Fairbanks researcher Anna Lilijedahl and her coauthors, arriving at this conclusion meant uniting two different disciplines. “I came to realize by talking to colleagues and friends and reading papers that in the Arctic, the glaciology and hydrology communities are often doing the same things in parallel,” Lilijedahl told GlacierHub. “I saw an opportunity to link the two—what happens when water leaves a glacier and travels hundreds of miles to the ocean?” she wondered.

A map shows the relationships between the study areas (Source: Lilijedahl et al, 2017/Geophysical Research Letters).

As her study area, Lilijedahl chose the Jarvis Creek watershed, which she called “accessible by Alaska standards,” meaning it runs parallel to the Richardson Highway and can be reached without a helicopter. The discontinuous permafrost that underlies this basin is characteristic of Interior Alaska, and Lilijedahl considers the region a proxy of other glaciated watersheds north of the Alaska range that lack road access.

To examine the relationship between glaciers, permafrost, and streams, Lilijedahl took a trip back to an older, colder time in Interior Alaska. She examined the Tanana River winter discharge record, which began in Fairbanks in the 1970s. It shows a steady increase in wintertime flow, as do similar records of streams across the Arctic and subarctic. She also analyzed satellite data and found that glacier coverage in the Tanana River watershed (of which Jarvis Creek is part) decreased by a remarkable 12 percent between 1950 and 2010.

Armed with this historical data, Lilijedahl and her team turned toward the present conditions of Jarvis Glacier and the Tanana River watershed. Scientists from the U.S. Geological Survey (USGS), the Army’s Cold Regions Research and Engineering Laboratory, and the Salcha-Delta Soil and Water Conservation District worked together to measure how much ice and snow Jarvis Glacier lost over the summer. They placed two gauges in the outflow stream, 55 kilometers apart.

Lilijedahl’s team deployed instruments in spring to determine how much ice melted over the summer (Source: Salcha-Delta Soil and Water Conservation District).

“This is the only study that I’m aware of that put two stream gauges in front of a glacier,” USGS glaciologist Shad O’Neel told GlacierHub. This innovative method yielded interesting results: the stream lost roughly 46 percent of discharge between gauges. Such staggering loss is probably happening globally, according to O’Neel. “Around the world, glaciers turn into braided rivers with an abundance of sand and gravel that’s particularly good at soaking up water,” he said.

The scientists don’t yet know how long this water remains in the aquifer, but it clearly stays at depth long enough to be warmed by the tectonically active ground that underlies the Alaska Range. The 6 degree Celsius temperature of the groundwater is an “indicator that water has traveled pretty deep before coming back up. The deeper you go into earth, the warmer it gets,” said Lilijedahl.

From the aquifer, the water leaks into Jarvis Creek through the winter. “Everything is frozen except groundwater, so that’s definitely the source,” added O’Neel.

As glacial melt increases, the water melts the surrounding permafrost, enlarging the aquifer. Though this means that storage capacity is higher, input will ultimately decrease as the watershed’s glaciers shrink in a warming climate. Eventually, local wells may run dry, and Lilijedahl believes that lowland areas of Jarvis Creek and other similar rivers could eventually go dry in the summer.

The Richardson Highway, seen here just north of Delta Junction, parallels the Jarvis Creek watershed (Source: Rachel Kaplan).

Drying streams would threaten an animal important to Alaskan culture and economy—salmon. According to the Alaska Seafood Marketing Group, “Salmon are responsible for the greatest economic impact (jobs, income, and total value) among all species in the Alaska seafood industry.” In 2013 and 2014, this industry generated an average of 5.9 million dollars of total economic activity. Salmon is also a crucial resource for people living subsistence lifestyles. “A lot of Arctic communities rely on chum salmon for food and pet food. Some species may do well, others won’t fare so well,” said O’Neel.

The health of salmon populations depends on a complex web of factors, including water temperatures in areas where eggs develop and stream levels where adult salmon migrate. Glacial melt and groundwater reserves shape both factors. Chum salmon eggs develop faster where warm water, between 3 and 6 degrees Celsius, bleeds into rivers. Salmon lay their eggs where the 6 degree Celsius groundwater upwells in the Tanana and Yukon rivers, according to Lilijedahl.

Glacial contributions to streamflow can also help support adult salmon. Glacial melt accounted for over 15 percent of Jarvis Creek’s annual discharge. For streams in the Alaska Range that aren’t glacially fed, said Lilijedahl, flow near mountains may yield to dry river beds a few miles downstream. “Imagine that if you’re a fish!” she said.

Salmon, such as the Sockeyes shown migrating here, are essential to Alaska’s economy and culture (Source: S. Huffman/NPS).

Thinking like a fish is key to many scientists and decision-makers in Alaska. The ancient migration habits of salmon have for millennia guided them between the ocean and their freshwater birthplaces, where they spawn before dying. Favorable conditions, such as water temperature and sufficient stream flow, constitute the difference between life and death, a poor year for Alaskan fisheries and a booming one.

The findings from this study will help in management of salmon populations. It will also help with understanding the impacts of climate change on a much broader scale. “In the past, we assumed all loss from glaciers ended up in ocean. But hey, wait—at least 30 percent in this system is lost in the aquifer. It introduces more complexities into this sea-level rise thing,” said O’Neel.

Faced with the complexities of a changing climate, myriad impacts of which are already shaping Arctic and subarctic landscapes, further collaborations between the hydrology and glaciology communities will be essential. “We’ve drawn a linkage between the physical systems of glaciers and the biological system of salmon. No one would have guessed that existed, not that long ago,” said O’Neel.

Lessons in Collaboration from the Tanana Watershed

This story is Part I of a two-part series on the Tanana River Watershed. See Part II here.

The Tanana River flows toward Delta Junction, with the Alaska Range in the background (Source: Rachel Kaplan).

What do a St. Patty’s Day party and a sub-Arctic river have in common? An abundance of green dye, which acts as a festive element for the first and a scientific tool for the second.

A group of Alaskan scientists used this green dye as a tracer in studying the intersection of glaciology and hydrology in subarctic rivers, and recently published their findings in Geophysical Research Letters. They found that glacial meltwater interacts with rivers and groundwater across the landscape in complex ways, which has implications for the life the landscape supports—including humans.

I spoke with the study’s lead scientist, Anna Lilijedahl, over Skype at opposite ends of our days. Anna, who was attending a conference in Oxford, sat on her hotel room bed in a sweatshirt that read “Yukon River Camp,” and I huddled in a sweater at my desk in Fairbanks, Alaska, listening as she talked to me about the sub-arctic Interior Alaska landscape I grew up in.

Small rivers are difficult to sample in winter, she told me, because of the thickness of the ice build-up. “Little channels of water run through it like a spider web, you can hear it in the ice if you listen,” she said.

From listening to wintertime trickles to trekking across glaciers, Lilijedahl and her team have engaged intensely with the Tanana River watershed, a major tributary of the Yukon River. Internationally important to subsistence lifestyles, remote northern travel, and commercial salmon fisheries, the river flows over 2,000 miles through Alaska and Canada before draining into the Bering Sea.

The glacial headwaters of Jarvis Creek are in the Alaska Range (Source: Salcha-Delta Soil and Water Conservation District).

Lilijedahl’s study involved extensive surveys on Jarvis Glacier, snow machine travel in the mountains, and probing frozen rivers to gauge their flow. What I noticed the most about Lilijedahl during our conversation was how she uses hydrology to bring people closer to their landscape, and to one another.

“We’re really excited about her work because it has a big impact not only on our community, but also for the agency,” said Jeff Durham, program director of Salcha-Delta Soil and Water Conservation District, a state agency that works with local landowners and government agencies to manage natural resources in nearly four million acres of Interior Alaska. The project constituted a collaboration between the University of Alaska Fairbanks, where Lilijedahl is based, the Salcha-Delta Soil and Water Conservation District, which provided logistical and backcountry support, and researchers from both the U.S. Geological Survey and a research branch of the U.S. Army.

According to Durham, this collaboration has drawn both attention and funding to the project. One proposal reviewer from the National Science Foundation wrote a letter naming this partnership as a hallmark of the scientific process, emphasizing that scientists should work with local agencies, not just live in the halls of academia. “It’s a great opportunity for us to jump in with her and get a lot of information. We can look forward toward what will happen with the water table and our community,” Durham said.

Delta Junction lies at the end of the Alaska Highway, one of the major arteries linking the U.S. and Canada (Source: Author Nader Moussa/Creative Commons).

As he drove through Interior Alaska, Durham talked to me by phone about what he calls the “boom and bust town” of Delta Junction, a small community near Jarvis Creek where you can leave a chainsaw in the back of your truck at the grocery store and it won’t be stolen. As Jarvis Glacier continues to melt, and eventually disappear, Delta Junction’s aquifer may dry up. When this happens, wells, which are a major resource in an area without municipal water, will run dry. According to Lilijedahl, the watershed’s glaciers are so diminished that the amount of water in aquifer storage is already decreasing.

Lilijedahl gave a presentation about her research findings in Delta Junction, surprising its residents with the importance of far-away Jarvis Glacier to the aquifer. Lack of understanding about the connection between mountain glaciers and lowland water resources is common, says Lilijedahl. Her paper in Geophysical Research Letters concludes that “high-latitude mountain glaciers represent an overlooked source to subarctic river discharge and aquifer recharge.” She calls the Jarvis Creek watershed a “proxy watershed” and believes the relationship between glacial melt and aquifer recharge exposed by her research will hold true for other subarctic regions in Alaska, Canada, and beyond.

“The fact that she’s worked so closely with a local natural resource agency, shared information, made an effort to come into the community—that’s the key in what Anna’s doing,” said Durham. “She brings complicated information into our community and makes it palatable. It’s easy to have those conversations in the halls of academia. Having them with someone who doesn’t have the background is the real challenge.”

Colin Barnard probes the snow in Jarvis Canyon (Source: Salcha-Delta Soil and Water Conservation District).

With regards to Jarvis Glacier and Delta Junction’s water resources, the future is coming. When will the water levels drop? In Durham’s lifetime or his children’s? As water pours from Jarvis Glacier into the aquifer, it melts the permafrost and carves the aquifer deeper, increasing water storage capacity and releasing carbon stored in the permafrost. This process raises a host of future research questions for Lilijedahl. “How much permafrost have we really thawed because of this increase in glacial melt?” she wonders. “This melt brings old carbon stored for thousands and thousands of years into the river, and in contact with bacteria.” Typically, attention is focused on glacial melt’s contribution to sea level rise, she says, but there are several directions in which to explore the impact on the terrestrial ecosystem.

Alaska is ground zero for climate change, according to Durham. “It’s obvious that the Jarvis is drying, we can see that from a visual standpoint. It’s a canary in a coal mine, and that’s why this work is so important,” he said. He expects the state to see impacts from temperature rise before other places. “How will we build, and how will we deal with what has been built?” he wonders.

Lead scientist Anna Lilijedahl during winter field research (Source: Salcha-Delta Soil and Water Conservation District).

Melting permafrost has impacts all over Alaska, Durham says. Roads undulate, the ground becomes unstable, and the ultimate consequences for towns and infrastructure are still unknown. One consequence for Delta Junction’s infrastructure may actually be positive: stable through the year, Jarvis Creek discharge has a temperature of 6°C, the signature temperature of aquifer water in the watershed. Though it sounds chilly, this is actually warm, especially relative to winter temperatures in the region. Lilijedahl thinks that people in Delta Junction could use the water as heat source to warm their homes.

With major changes to life imminent in Delta Junction and other places in Alaska, partnerships between scientists and local agencies will lead the way in research and future mitigation efforts. As the landscape changes, the only choice is to draw closer to it, and to one another.

Girls Breaking Ground on Ice

As a student, I had no idea that I ever wanted to study anything related to science- much less the “hard” sciences. Often, I was pointed in the direction of social science because of my writing ability and creativity. Although my high school days weren’t long ago, this experience is common among young women due to archaic stereotypes that have yet to be dismantled. Luckily, there are some female professionals in the hard sciences, such as Dr. Erin Pettit, glaciologist and founder of the Girls on Ice Program, who are trying new approaches to open corridors in science for young ladies.

(Photo: Facebook)
Young women who participate in the program represent a variety of backgrounds and geographic locations. (Photo: Facebook)

 

Sponsored by the University of Alaska Fairbanks, Girls on Ice is a free science, mountaineering, and art wilderness program for young women ages 16-18. Each year, two teams of nine young women and three instructors spend twelve days on unforgettable expeditions: one trip explores Mount Baker, an ice-covered volcano in Washington, and the other trip allows the young women to experience the majesty of Alaska’s Gulkana Glacier. The young women selected for the teams explore these unique landscapes with professional mountaineers, ecologists, artists, and glaciologists, and all of the instructors are women.

GOI Poster

 

The program stretches the young women mentally and physically by prompting them to observe, to question, and to experiment while trekking through rough terrain. Although the focus is scientific research, the physical elements cannot be overlooked. “We don’t baby them. They have to set up tents, cook, do everything,” declared Dr. Pettit to the National Science Teachers Association. Over the course of the expedition, the girls are challenged to design and conduct a pinnacle experiment about the environment; during the 2009 expedition, one participant used time-lapse imagery to correlate local weather and glacial melt. She found that air temperature and sunshine have a direct effect on the melt rates of ice and snow cover, thus affecting the pace of water-flow in glacial streams. After the expedition, the young women are invited to synthesize their field research and present it to a public audience, which sometimes includes members from the local geoscience community.

 

The young women partner with professionals in order to gain a comprehensive understanding of their new environment. (Photo: Facebook)
The young women partner with professionals in order to gain a comprehensive understanding of their new environment. (Photo: Facebook)

 

The young women on the Girls on Ice team gain both physical and intellectual confidence, leadership skills, and inspiration for future achievement. Yet, along with stimulating the minds of the young women, the program has benefits for society as it helps to close the gap between the numbers of women and men involved in science occupations. According to National Geographic, women make up a meager 26% of the individuals devoted to science, technology, engineering, and math occupations; although that number has been increasing slightly over the years, “gender bias has affected research outcomes.” Programs like Girls on Ice help to ameliorate these injustices by providing unique opportunities for girls to experience the grandeur and marvel inherent in scientific discovery. As stated by one of the participants, “I am inspired to do anything! In the van ride back I was looking out the window at the amazing scenery and the bright blue sky and I felt so great and excited for life.”

The program allows the young women to grow as scholars, but also allows personal reflection time. (Photo: Facebook)
The program allows the young women to grow as scholars, but also allows personal reflection time. (Photo: Facebook)

 

Dr. Pettit stated in her feature in Smithsonian, “My goal is not to turn these girls into scientists. My goal is to provide the kind of critical-thinking skills that are necessary for science-and for everything else we do in life.” The aim is to inspire these young women to become not just scientists, but also “future teachers, journalists, lawyers, and businesswomen who are advocates for the scientific process.” Therefore, this program and other field science experiences for high school students offer a promising outlook on the importance of preserving glaciers and their magnificent environments. Not only are these areas important for their immediate ecosystems, but they have the potential to inspire the curiosity and achievement of many generations to come.