Hydrology and Geology Researchers Assess Critical Zone Observatories

Hydrology and Geology Researchers Assess Critical Zone Observatories
Danielle Gerrard, a UW undergraduate student from Evanston, collects electromagnetic induction (EMI) data in the Reynolds Creek CZO in Idaho earlier this summer. The EMI instrument provides an estimate of soil moisture content. (Brady Flinchum Photo)

LARAMIE WYOMING — For the price of gas, food and lodging, University of Wyoming hydrology and geology researchers have traveled across the country the past two summers to examine Critical Zone Observatories (CZOs), projects that have created significant use of UW’s hydrology instrumentation and built important collaborations with scientists from major universities.

These sites encompass watersheds where groups of scientists can collaborate and work across disciplines to develop a more complete understanding of the biological, chemical, geological, hydrological and physical processes that operate in the Critical Zone, which is defined as the region from treetop to bedrock that supports most life on Earth.

“I think of it (Critical Zone) as the breathing skin of planet Earth. It’s like this membrane tens of meters thick,” says Steve Holbrook, a UW professor in the Department of Geology and Geophysics, and co-director of the Wyoming Center for Hydrology and Geophysics (WyCEHG). “Across this membrane is the transfer of things impactful for life — water, chemical compounds and nutrients.”

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To understand the complex cycles of carbon, nitrogen, oxygen and water that run through these Critical Zones, research has to be conducted in an integrated way, Holbrook says. This includes using the combined expertise of atmospheric scientists, botanists, geologists, geophysicists, hydrologists and soil scientists.

Six years ago, the National Science Foundation (NSF) established a network of five CZOs stretching from Puerto Rico to California. Today, there are 10, ranging in size from “as small as a little catchment or as long as a watershed,” Holbrook says.

During the past year, WyCEHG’s geophysics team has worked at six of the 10 CZOs. These include Calhoun, S.C.; Boulder Creek, Colo.; Reynolds Creek, Idaho; Eel River, Northern California; Southern Sierra, Southern California; and Jemez-Catalina in Arizona and N.M. This summer, Holbrook had 13 UW students available to accompany him to these sites.

“I think we’re the only group that’s worked at this many sites,” he says. “We get to collaborate with great scientists from other universities. It’s been a huge benefit and source of pride for us.”

The UW group has worked with researchers from nearly 15 universities, including Duke, Johns Hopkins, MIT and UC-Berkeley. These universities have secured grants to conduct the field research. In exchange, Holbrook, through the WyCEHG grant, pays for his student crew and the equipment.

“We ask that they (universities) pay for expenses,” which includes gas, food and lodging, he says.man using slegdehammer with mud flying around

During these stops, Holbrook and a number of UW graduate and undergraduate students are able to collect large amounts of data quickly with WYCEHG equipment, which includes seismic, electrical resistivity, electromagnetic induction, ground penetrating radar and magnetic instrumentation.

“All people working at CZOs are coming to the realization that, in order to succeed in their scientific goals, they needed to dig deeper,” Holbrook explains. “Most of them didn’t have a geophysicist. They were missing that part. We provided a unique component that they needed. Most universities don’t have a lot of the equipment we have.”

During visits to multiple Critical Zones, Holbrook says the most interesting discovery was that, at watershed sites that were compared, a new physical insight into what controls the distribution of the porosity in the subsurface was realized. He says the work, conducted with researchers from MIT, is expected to be published in a well-known science journal this fall.

“It’s been a fantastic experience for our graduate and undergraduate students,” Holbrook says. “I’m proud of this team. At every one of these sites we go to and work at, when we pack up our site to leave, they (other university researchers) say you have a terrific team.

“This provides lots of benefit to UW. It’s putting us in a position to write more grant proposals and secure future funding once the WYCEHG grant expires.”