TEMPERATURE VARIATIONS IN THE HYPORHEIC ZONE OF RED CANYON CREEK, WIND RIVER RANGE, WYOMING

Characterizing vertical differences in pore water temperature in stream beds can be used to gauge the extent to which hyporheic interaction occurs. Simple, inexpensive data loggers, such as the iButton technology made by Dallas Semiconductor, allow long term accurate temperature observations within and adjacent to stream channels in order monitor hyporheic flow. These measured temperature fluxes can be applied to models for energy and heat transport (VS2DH) to indirectly evaluate differences in the hydraulic conductivity of the sediment in the stream channel and the adjacent stream bank.

We characterized temperature differences with depth in stream sediments in Red Canyon Creek, a small second order stream located in the semi-arid climate of the Wind River Range in Wyoming. IButtons were inserted into wooden dowels and driven into the streambed in order to monitor temperature in the stream channel and at depths of 5cm, 15cm, and 25 cm. The iButtons recorded temperature to 0.065 degrees Celsius at 1.5-hour intervals from 7/11/05 to 10/14/05. Clear diurnal patterns in temperature occurred at all depths, and lag times between installations range from 4 hours to 12 hours across the vertical profiles. Differences between selected locations mirror data gathered from piezometer readings, where the amplitude of the temperature fluctuations are directly related to the extent to which reaches were gaining or losing. For example, over a 24-hour period temperature remains a consistent 14° C at 25 cm depth in a groundwater discharge zone downstream of a tight meander. This is in contrast to readings in a surface water recharge zone located in a large gravel bar where temperature at 25 cm varies from 16° C to 19° C for the same 24-hour period.