Ice wedges are a common ground-ice feature in continuous permafrost landscapes, often identified from fields of polygonal terrain. While gradual warming of permafrost has been well-documented across Pan-Arctic landscapes, ice wedge rate of cracking and melt is uncertain, resulting in ambiguities in understanding the effects on surrounding hydrology. Especially pertinent in the western Arctic is the potential influence of ice wedge cracking and melt on “catastrophic thermokarst lake drainage” (CTLD). This process can completely drain a lake in less than a day when lake water melts a channel through massive ground ice. Mackay (1988) suggests that the primary process for CTLD is high lake level entering winter cracks through ice-wedge polygons, allowing tunnel flow. This results in wedge ice melt followed by rapid lake drainage. These CTLD events are important as they drastically alter aquatic environments, impacting fish and wildlife habitat, pose flooding risk to people and infrastructure downstream and impact the broader climate system though changes in lake surface area. Despite the impact on society, ecosystem and global climate, the controls and rate of ice wedge cracking and melt and the subsequent impacts on lake drainage are poorly understood. There is a need to integrate hydrology and permafrost science at the watershed scale through remote sensing of past changes, observations of current conditions and modeling the future of permafrost-lake systems. We have proposed an interdisciplinary research program using high resolution field data for Trail Valley Creek, a study site in the western Canadian Arctic rich in thermokarst lakes susceptible to drainage. This project will integrate field data with existing high-resolution remote sensing maps of ice wedges around lakes and test, improve and apply high-resolution mathematical models of permafrost-lake-hydrology systems. Specifically, this project aims to better understand the processes controlling CTLD, the importance of ice wedge cracking and melt on lake drainage, the factors that have impacted past lake drainage events, and future changes to ice-wedge polygon degradation and CTLD. We will outline preliminary model development and site selection of this project and upcoming activity. This work will contribute to wider efforts in understanding the impacts of climate change on permafrost and hydrology in the Northwest Territories and across the Arctic.
Mackay, J.R. 1988. Catastrophic lake drainage, Tuktoyaktuk Peninsula area, District of Mackenzie. In Current Research, Part D. Geological Survey of Canada, Ottawa, ON. Paper 88-1D: 83-90.