Supervised by:

Richard Fortier (Regular member)

Co-supervised by:

John Molson (Regular member)

Research project description

Monitoring and numerical modelling of thaw consolidation and settlement of ice-rich permafrost in Umiujaq, Nunavik (Québec), Canada

IntroductionGlobal warming in excess of 3°C observed in Nunavik (Québec), Canada, since the beginning of the 1990s has had major impacts on permafrost degradation. The main evidence of this degradation is the thaw settlement of permafrost. This natural hazard affects not only northern ecosystems but also man-made infrastructures. Moreover, among the few positive impacts of permafrost degradation, melting water from ice-rich permafrost can infiltrate and migrate into the soil, and ultimately recharger the aquifers at depth. Therefore, groundwater could now be considered as a source of fresh water for Inuit communities. Groundwater is known to be more secure and less vulnerable to contamination than surface water, currently used by most of the Inuit communities as a supply of fresh water. ObjectivesIn order to answer to the previous problematic, the objectives of the research project are: 1) to study thaw settlements of permafrost in the Tasiapik Valley, 2) to conduct numerical modelling of thaw consolidation according to the recent climatic variability in Nunavik, and 3) to understand the physical processes behind the thaw settlements observed. Study sitesThe Tasiapik Valley is located near the Inuit community of Umiujaq in Nunavik (Québec, Canada) in the discontinuous permafrost zone. Degrading ice-rich permafrost mounds are found in the Tasiapik Valley. Material and methodsAnnual monitoring of thaw settlement of permafrost mounds in the Tasiapik Valley has been conducted since 2004 with a high-resolution laser-based remote sensing method for producing digital elevation models (DEMs) called LiDAR (Light Detection and Ranging). In addition to pursuing this monitoring in 2022 and 2023, DEM data already acquired will be processed to assess the spatial distribution of differential thaw settlement. Moreover, the numerical code HEAT FLOW/SMOKER will be slightly modified and then used to achieve numerical modelling of coupled physical processes of groundwater flow, heat transfer, and thaw consolidation. Simulated thaw settlement will be compared to the ones observed to constrain the numerical modelling. Future thaw settlements will also be predicted according to different scenarios of climate warming. Expected resultsA better understanding of impacts of climate warming on permafrost and physical processes controlling permafrost dynamics will be obtained through both the monitoring and numerical modelling of thaw settlement of ice-rich permafrost in Umiujaq. This knowledge could be used for man-made infrastructures in the North built on permafrost whose performance, maintenance costs, and service life are affected by thaw settlement. The study of this natural hazard and its impacts is fundamental to ensure the sustainable development of Inuit communities in Nunavik by adapting construction methods to this changing Nordic environment.

Scientific Communications

St-Cyr, M., 2023..