Department of Geology and Geological Engineering
Jean-Michel Lemieux (Regular member)
John Molson (Regular member)
Introduction: In northern regions, permafrost degrades due to climate change, resulting in several impacts on civilian infrastructure and natural environments. Thawing permafrost can change the water cycle from a predominantly summer surface flow regime to a perennial flow regime supported by groundwater flow following permafrost degradation. In order to anticipate these impacts, it is important to predict the permafrost dynamics. Numerical modeling studies of permafrost degradation generally conceptualize heat transfer as occurring exclusively by conduction. However, it has recently been suggested that groundwater flow in permafrost zones can increase thawing rates due to heat advection. The impact of additional groundwater flow in cold environments could have a profound impact on the rate of permafrost degradation. Objectives: The objective of the project is to validate the hypothesis that groundwater flow can play an important role in permafrost dynamics from long-term observations of temperature and groundwater flow for an instrumented study site located near Umiujaq, in Nunavik (Quebec), in the discontinuous permafrost zone. By instrumenting this site with high spatial and temporal resolution, and using a numerical simulation model of groundwater flow and heat transmission, more accurate predictions of permafrost thaw in the context of climate change will be carried out considering heat transmission by conduction and advection. As a result, the role of groundwater flow and advective heat transport in permafrost dynamics will be better understood.Study sites: The chosen study site is a permafrost mound located near the community of Umiujaq in Nunavik (Quebec). This site is chosen because it has been the subject of several investigation campaigns to document the spatial extent of permafrost and deploy monitoring instrumentation. This exceptional instrumentation includes thermistor cables, groundwater observation wells, temperature and water content sensors in the active layer, heat flux plates and a snow cover monitoring system. Material and methods: As part of this project, new groundwater observation wells were installed on the periphery of the mound to document spatial variations in groundwater flow and to improve existing instrumentation as well as to carry out a 3D cryohydrogeological characterization. Geophysical surveys were also conducted to obtain a 3D image of the permafrost mound and map the depth of the water table. The available data will then be incorporated into the SUTRA-Ice numerical model, developed by the United States Geological Survey (USGS), which simulates conductive and advective heat transmission, while also including groundwater flow and phase change.Expected results: Heat transmission simulations will be performed in the model to quantify the role of groundwater flow on permafrost dynamics. Predictions of permafrost thaw in the mound will then be made considering climate change. At the end of these simulations, the expected results are a more realistic prediction of permafrost degradation, in a context of climate change, which will be representative of a large portion of the subarctic territory.
Fortier, P., Young, N., Lemieux, J.-M., Walvoord, M., Fortier, R., 2023. Long-term, high-resolution permafrost monitoring reveals coupled energy balance and hydrogeologic controls on talik dynamics near Umiujaq (Nunavik, Québec, Canada). Water Resources Research(59). DOI: https:// 10.1029/2022WR032456.
Germain, A., Young, N., Lemieux, J.-M., Locat, A., Delottier, H., Fortier, P., Leroueil, S., Locat, P., Demers, D., Locat, J., Cloutier, C., 2021. Hydrogeology of a complex Champlain Sea deposit (Quebec, Canada): Implications for slope stability. Canadian Geotechnical Journal, 58(11): 1611-1626. DOI: 10.1139/cgj-2020-0500.
Young, N., Lemieux, J.-M., Delottier, H., Fortier, R., Fortier, P., 2020. A conceptual model for anticipating the impact of landscape evolution on groundwater recharge in degrading permafrost environments. Geophysical Research Letters, 47(11), e2020GL087695. DOI: 10.1029/2020GL087695.
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