Thermal Regime of Stream Channels in Continuous Permafrost, Western Canadian Arctic

In permafrost regions, the movement of water during winter has important implications for hydrology, land use, and infrastructure. Knowledge of winter hydrothermal dynamics in small, extensive tundra stream networks is limited. Climate warming, changing precipitation regimes, and increases in tundra vegetation coverage may delay active layer freeze-back, potentially increasing winter water movement. The primary goals of this research are to improve knowledge of the thermal regime of small stream channels in continuous permafrost, explore the implications of a changing climate and runoff, and describe the influence of infrastructure on channel thermal regime. A program of temperature monitoring in stream channel beds and riparian margins between Inuvik and Tuktoyaktuk is presented here. Preliminary results, if representative of several years, suggest that permafrost is not present at depths shallower than 3.5 m below the bed of a small stream with a contributing area of <30 km², and that this layer does not likely re-freeze during winter. This thermal regime may be modified by highway crossings that reduce or eliminate stream snow cover, and the degree of thermal disturbance may be a function of contributing watershed size. This research and further related work have the potential to provide new insight on channel thermal regime and winter hydrology in permafrost regions, offer projections of change in the context of a warming climate, and help inform the design, operation, and mitigation of hydrological issues associated with linear infrastructure in permafrost.