Hydrothermal Regime of Stream Channels – Tuktoyaktuk Coastlands and Anderson PlainThursday, November 22, 2018 - 11:00 to 11:19 Theatre 3
In permafrost regions, the movement of water and extent of winter freezing in streams have important implications for hydrology, terrestrial and aquatic ecology, land use, and infrastructure. Although the hydrology and thermal characteristics of large Arctic streams and rivers have been investigated, knowledge of contemporary winter hydrothermal dynamics in smaller, more extensive tundra stream networks is limited. Climate warming, changing precipitation regimes and increases in tundra vegetation height and coverage may combine to delay active layer freeze-back, increasing the potential for winter water movement. This could influence stream hydrothermal regime, with significant hydrological and ecological consequences.
The primary goal of this research is to improve our understanding of the hydrothermal regime of small stream channels in continuous permafrost in the Tuktoyaktuk Coastlands and Anderson Plain, NWT, and to explore the implications of a changing climate. It is hypothesized that insulation from snow cover in combination with adequate watershed storage capacity can permit flow to continue through winter in small stream channels. To test this hypothesis, water and ground temperature in, beneath, and adjacent to streams of varying catchment size across treeline is being monitored. Morphological and ecological parameters of contributing watersheds are being compared, and the hydrological activity, thermal conditions and the distribution, timing, and magnitude of stream icings indicative of winter water movement are being described for several streams intersected by the 130-km Inuvik to Tuktoyaktuk Highway (ITH).
The ITH has likely increased the surface expression of winter water movement in regional streams, and has facilitated logistics and field observations. An additional research objective is to describe the causes of the icings and ground injection ice occurring at stream crossings along the highway. It is hypothesized that changes to the stream thermal regime caused by bridge structures or culverts contribute to the upstream development of icings. Concurrent continuous monitoring of streambed temperatures, hydrostatic water level upstream and downstream of highway crossings, snow accumulation and icing size is intended to aid the investigation of causes and processes of formation. The development of icings is a concern because of the potential for unsafe road conditions, highway blockages, or highway damage.
This research provides new insight on winter hydrology in permafrost areas, and demonstrates that significant mass and heat continues to move through small hydrological systems in winter. The results will inform hydrological modeling, understanding the evolution of stream chemistry and will help inform the design, operation and mitigation of hydrological issues associated with linear infrastructure in permafrost.