Studying Hydrology from the Inside Out
Pictured above: Professor Matt Covington of the Department of Geosciences explores caving systems around the world | Photo by Matt Reynolds
Snow still blankets the ground on this 30-degree February afternoon as Matt Covington prepares to crawl through mud beneath the earth’s surface. The empty parking lot at Blowing Springs Park in Bella Vista, Arkansas, allows him to suit up without attracting attention. First he dons long underwear, followed by a neoprene wetsuit and a pair of dark green coveralls — a sacrificial layer intended to prevent the wetsuit from being shredded on sharp rocks. He tops it off with a helmet, boots and gloves. He’s ready.
Covington, an assistant professor in the University of Arkansas’ Department of Geosciences, and his assistant Alex Breeding, a senior geology major, are making a monthly visit to change batteries and download data from devices placed throughout the 8,000-foot long cave. The devices gather data on air and water temperature, as well as carbon dioxide levels for a variety of research projects Covington oversees with his undergraduate students. The cave is a laboratory you have to wriggle into.
The pair open the locked gate that keeps casual spelunkers out and hoist themselves over a flat, waist-high rock. They drop down into a running stream and belly-crawl through the muddy water. Headroom is tight at first, but the cave opens up further in, where they’ll walk through chest-high water to access their equipment.
It would be a stretch to call this just another day at the office. Like many professors, Covington spends most of his time teaching. Caves are both a profession and an avocation for him. He’s managed to do what many of us only dream about: Combine his work and his hobby.
[metaslider id=5875]Covington studies the mechanical and chemical processes of erosion and the relationship between springs and the internal structure of aquifers. Such relationships are most complex in karst topography, which is characterized by sinkholes, underground drainage systems and caves. Understanding the intricacies of karst can help municipalities manage water resources and deal with the hazards of pollution and spills.
As a caver and adventurer, he’s been on expeditions probing the world’s deepest caves in places as far flung as Mexico, Peru, Sumatra and China. He’s discovered and mapped caves, camped underground for days, scuba-dived in lakes hidden deep in the earth and put himself through physical trials only the truly obsessed would endure. In 2008, while exploring Lechuguilla Cave in New Mexico, he fell and broke his arm two days into an eight-day trip when an anchor popped loose during a climb. He set his own arm deep in that cave and passed out from the pain. When he awoke, Covington climbed for 13 hours through the cave to make it out without calling in a rescue team.
“I just like being outside,” he says. “But the thing that is particular about caves is the exploration aspect. It is really about the only thing an average person with an average budget can do and explore new places that people haven’t seen before. My other options would be going to space or the bottom of the ocean. And even the bottom of the ocean is mapped.”
Diving into Speleophysics
Covington grew up camping and hiking in Northwest Arkansas and credits his family with cultivating his love of the outdoors. He’s also a third-generation University of Arkansas faculty member; his grandfather, Jess Covington, was the chair of the journalism department, and his father, David Covington, was a professor of engineering.
With that lineage, it was almost a foregone conclusion that he would do his undergraduate work in Fayetteville. He graduated in 2002 with bachelor degrees in philosophy and physics.
While he meshed with qualitative principals of philosophy, Covington was also drawn to the quantitative nature of physics. He was good at the math and enjoyed building the predictive models physicists employ to perform research. With quantitative research in mind, he went on to the University of California, Santa Cruz, and, studying galaxy mergers, earned his Ph.D. in physics.
He was a year away from finishing that degree when a thought occurred to him: Geology can be quantitative too. It’s a field often considered qualitative because it attracts people who like science but not necessarily math. But once Covington realized that didn’t have to be the case, the light bulb clicked on.
“There was a day when I was sitting in a lecture on galaxy formation and the guy was talking about a statistical technique he was using, and somehow it hit me,” he recalls. “I wondered if I could use that technique to think about how caves form.”
That moment led to Covington becoming one of only six speleophysicists — cave physicists — in the world.
While on a break from an astrophysics conference in Germany, Covington traveled to Slovenia to find Franci Gabrovšek, a geologist he’d met at a caving conference in Texas. Gabrovšek had a background in physics.
“We talked all day about being a physicist studying caves,” Covington recalls. “He convinced me that it wasn’t crazy.”
Covington’s geology training was limited to a few classes he’d taken as a grad student, however. He was willing to head back to grad school and earn a second Ph.D., but instead landed two National Science Foundation Earth Sciences Fellowships, one studying karst hydrology in Minnesota and the other at the Karst Research Institute in Postojna, Slovenia.
When a faculty position came open in the University of Arkansas’ Department of Geosciences, Covington readily applied.
“Normally when you are getting an academic position somewhere, it’s not in your hometown,” he says. “It’s wherever you can find one. I had seen enough of the rest of the world and was happy to come back here to live close to family.”
Water on the Move
A relatively large amount of U.S. water resources, perhaps 20 percent, are found in aquifers that contain caves. That poses a water management problem.
“They are basically like pipe systems that run through an aquifer that allow water to travel very quickly over long distances possibly in difficult-to-predict directions,” says Covington.
Aquifers are underground water sources contained in porous rock and are often intersected by caverns or underground streams that move water quickly through an area. Aquifers also depend on the filtering effect of the layers of soil and porous rock above them to clean the water. But caves create pathways for water and, like a pipe, can move it and any contaminants that water may contain along too fast for filtering to take effect.
So understanding how caves form and predicting where they take water can be beneficial to resource managers.
At Blowing Springs, Covington is focused on the dynamics of carbon dioxide. He’s interested in how the cave’s airflow patterns influence the level of carbon dioxide in both the air and water. Carbon dioxide is a catalyst for dissolution of rock, and levels of it vary greatly by season. Covington’s data shows that carbon dioxide levels are up to 10 times higher in the summer than the winter.
That helps him understand how and when caves erode. It’s a line of research that hadn’t been much explored until now.
“No one has collected a dense enough data set to say much about it,” he says.
Until recently, it wasn’t easy to even collect data on carbon dioxide levels in water. Covington had to modify an air sensor by wrapping it in a waterproof membrane to get the data he wanted.
“For the first time, we have study data of Co2 concentrations in cave water,” he says.
The Thrill Isn’t Gone
Turning an avocation into a living is risky. What if you end up burned out on both?
“I wondered if it was dangerous to my hobby and my career,” he says, “like caves are just not going to be fun anymore.”
Instead, science has given him a new way of seeing the world underground, one that involves mathematical modeling rather than pushing physical boundaries. And there’s satisfaction knowing that time spent rappelling down waterfalls, squeezing through cracks and wading in knee-deep mud could have real-world implications. Being on the team that lays claim to the world’s deepest cave will be an achievement akin to conquering the world’s tallest mountain. Understanding the hydrology of karst topography could mean safer water supplies for cities around the world.
But, like a mountain climber who becomes a guide to extend his days at elevation, Covington still feels the tug that got him hooked in the first place. In 2013, on a trip to J2, a deep cave in Oaxaca, Mexico, Covington spent most of his time collecting data instead of probing for passages that would extend the cave’s known depth.
“It was a little bit sad for me,” he recalls. “I was no longer out there at the edge. I was working, measuring the sizes of potholes and trying to download data from my data loggers. It was still fun to be down there, but it was a change.”
He hasn’t given up exploration entirely. He plans to return this summer to Slovenia for another look around a cave he discovered there while on a Sunday afternoon hike.
“My relationship to caves and caving has changed,” he says. “There are good things about that. Expedition caving is hard on your body. Science is a way I can still interact with caves in a much less physical way. It is more sustainable.”