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September 5, 2013 — For the past year, University of Wyoming water researchers, with boots on the ground, have used more than $1 million worth of new geophysics and hydrology equipment to map groundwater aquifers in the Laramie and Snowy ranges.
Soon, they also will be able to tackle their research from the air.
A SkyTEM airborne geophysical system, provided by Aarhus University in Denmark, will be used to collect geophysical measurements in the Laramie and Snowy ranges starting either Sept. 10 or 11. Suspended from a helicopter, the system collects and delivers accurate and detailed maps of the earth’s subsurface quickly and economically. The system can identify, map and characterize -- in 3-D images -- subtle variations in electrical conductivity and magnetization from the near surface to depths of hundreds of meters.
The SkyTEM technology -- which resembles a giant loop of wire -- can take electrical conductivity readings over an area one-third the size of a football field at any given time. To cover the mountainous terrain, the helicopter will fly back and forth in rows, much like the pattern a lawnmower makes to cut grass.
The technology probes the ground with a signal. If bedrock aquifers are present, a strong signal will be sent back, explains Steve Holbrook, a professor in UW’s Department of Geology and Geophysics.
“What this helicopter research will give us is a large, but rough, map of the subsurface structure,” says Holbrook, who also is co-director of the Wyoming Center for Environmental Hydrology and Geophysics (WyCEHG). “We can use that (map) to guide our more detailed subsurface research with our ground equipment. We’ll be able to tell where the water might be, but not the source.”
Simon Ejlertsen, an electronics engineer who is part of the HydroGeophysics Group at Aarhus, will visit UW this month. He will serve as field manager during the five days of research.
“I will help with technical support on the project in case of equipment failure,” Ejlertsen says.
“The role of the field manager is to manage the field work and the operation of the instrumentation,” says Esben Auken, an associate professor in the Department of Earth Sciences at Aarhus. “Together, with his assistant, he makes sure that data meets the standards; the instruments are working; the pilot flies the way he is expected to; and has the right flight lines. There is a lot of communication with the pilot before take-off, during take-off and during landing.”
For previous research projects, Aarhus has flown the SkyTEM equipment over mountainous regions, including Mayotte Island and the Galapagos Islands, Auken says.
“It is not a problem, except that the pilot has to lower the flight speed a bit and he has to be even more aware of the terrain compared to a flat terrain,” Auken says.
An international partnership
The collaboration with Aarhus is part of the outreach component of a five-year, $20 million grant award from the National Science Foundation (NSF) to Wyoming’s Experimental Program to Stimulate Competitive Research (EPSCoR). The grant, the largest in UW’s 127-year history, provides for new physical and intellectual infrastructure that enables a comprehensive research program that links surface and subsurface watershed hydrology, geophysics, remote sensing and computational modeling.
When UW put its grant application together, it specifically included a letter of support in its grant application that would allow for the university to collaborate with Aarhus and be able to use its SkyTEM equipment, Holbrook says. Without the partnership, such technology would cost about $500,000 to purchase.
“We have been doing research, but we can only cover so much ground with our equipment,” Holbrook says of work on the ground locating aquifers in the Laramie and Snowy ranges. “We can’t characterize a large watershed effectively. We envision using airborne technology to cover a large chunk of real estate, and target spots we can go to. It makes us more efficient.”
Holbrook and Brad Carr, a UW senior research scientist in geology and geophysics, visited Aarhus in April and met with Casper Kirkegaard, a software group manager and post-doctoral student there, to learn more about the SkyTEM technology. Kirkegaard visited Laramie in May to conduct some reconnaissance of the mountainous areas to prepare for the fall research.
In late July, the SkyTEM equipment arrived in Laramie and was shipped south, where it was first used to conduct similar ground sweeps in parts of Oklahoma and Texas before it was returned to Laramie in preparation for the UW project, Holbrook says.
Ryan Armstrong, a new UW graduate student via Colorado College, will travel to Aarhus this month to learn more about the SkyTEM software and how to interpret the data gathered by SkyTEM.
“This is a very high-profile project,” Holbrook says. “This data is important to us. I’m confident Ryan will do a good job.”
Using the conductivity information gathered by the SkyTEM equipment, UW researchers and students will be taught data processing and presentation, and geological/hydrological modeling, based on the data, Auken says.
Holbrook realizes the sight of a low-flying helicopter -- carrying what looks like a large suspended net -- may alarm residents and livestock in Centennial, a town that sits at the foot of the Snowy Range. To get out the word about the research, Holbrook plans to dispense fliers to residents of the town and alert the Albany County Sheriff’s Office.
As new aquifers are located using the SkyTEM equipment, UW researchers will still have to conduct their core work. This includes taking water samples and conducting isotope tests to determine whether water comes from snowmelt, rain or deeper sources.
“Geophysics doesn’t give us the final answer,” Holbrook says. “It gives us a building block on which to base these other disciplines.”
The September visit does not mark the end of UW’s partnership with Aarhus. Holbrook says UW has begun a scientific collaboration with the Denmark university, one that will include mutual visits among researchers as well as a student exchange.
A helicopter carries SkyTEM airborne geophysical equipment over a mountain range in Greenland. SkyTEM equipment, provided by Aarhus University in Denmark, will help UW researchers locate watersheds in the Laramie and Snowy ranges during research that will begin either Sept. 10 or 11. (Lars Rasmussen Photo)