This summer we deployed a fiber-optic temperature monitoring technology called Distributed Temperature Sensor (DTS) in the No-Name drainage in the Medicine Bow National Forest. DTS works on the principle that the optical properties of telecommunication-grade glass fiber cables vary with temperature. A laser sends light pulses down a protected fiber and a sensor records any changes in the character of the light pulse, then back calculates temperature at every meter along the fiber, which can be several kilometers long. This provides very high spatial resolution, unmatched by other environmental temperature sensing technologies. This stream Influxes of groundwater to the channel are identified where abrupt changes in temperature are revealed; temperature changes in the channel due to atmospheric induced warming and cooling occur gradually along the DTS system. This system can identify gains that may occur via return flow or subsurface lateral flow. Over the summer, we deployed a DTS leased from Center for Transformative Environmental Monitoring Programs (CTEMPS) in two of WyCEHG’s high-intensity study sites. In the No-Name Creek Watershed, the DTS was deployed on a steeply sloped 550 m reach of stream to look for temperature signals that indicate exchange between the surface water and groundwater. This watershed is severely effected by trees that have succumbed to the pine bark beetle, and therefore it was an arduous deployment requiring many WyCEHG volunteers to navigate the many fallen logs that crossed the stream. Once set up, the autonomous DTS system collected data every ten minutes for 16 days without a hitch. The rich temporal and spatial temperature data we collected allows us to identify zones of groundwater exchange, and investigate the stream’s response to solar radiation and the ambient environment. A second reach of stream –the Blair tributary – was also instrument with DTS to measure inflow along the channel through interpretation of small changes in bed temperature. The Blair tributary has a much shallower slope than No-Name, and it not affected by deadfall. Installation was much more straightforward, however a new challenge arose: beavers found and damaged the cables during measurement. Although the DTS instrument required quite a bit of work by many people to install, this turned out to be great benefit. We were able to involve many “volunteer” WyCEHGers including graduate students from a variety of disciplines and several Summer Research Assistantship Program (SRAP) pre-college students that were doing research apprenticeships over the summer. This was a valuable opportunity to expose students to the hydrogeophysics research that is fundamental to WyCEHGs mission and excite the next generation of scientists with hands-on field experiences.

Raw project data is available by contacting ctemps@unr.edu