Profile

Adèle Joyeux
Ph.D. student
Department of Applied Geomatics
University of Sherbrooke
Adele.Joyeux@USherbrooke.ca

Supervised by:

Frédéric Bouchard (Regular member)

Co-supervised by:

Alexandre Langlois (Regular member)

Research project description

Multi-scale study of active layer freeze/thaw cycles and permafrost dynamics in a limno-scape context, near Cambridge-Bay, NU

Introduction: High Arctic regions are very sensitive to current climate change. Permafrost is intimately linked to the hydrological network, therefore a change in one will affect the other. Thus, the destabilization of permafrost due to the increase in temperature will impact the hydrological network. What are the spatial and temporal patterns of the freeze/thaw cycles of the water circulating in the active layer and how do they interact with the hydrological network, especially with the lakes? In the field, the manifestations of freeze/thaw cycles can be observed at a meter or even centimeter scale. How can this signal be characterized by remote sensing with pluri-metric to pluri-kilometric resolutions? How to link regional observations in remote sensing with specific localized field data?Objectives: Propose a multi-scale approach to map lakes and freeze/thaw patterns. Characterize their links by carrying out a morphometric study. Use passive and active microwaves to characterize freeze/thaw cycle patterns. Collect in situ data on soils and lakes in the field to validate remote sensing results.Study sites: Iqaluktuuttiaq (Cambridge Bay) literally translates to: “place where it is good to fish”, the local populations are directly dependent on water resources and fish because of their traditional way of life. The landscape around the village has been sculpted by the retreat of the Laurentian continental ice sheet, formed during the last glacial maximum, around 21–18 ka BP. This has created a very complex landscape with diverse periglacial structures. The tundra type vegetation presents sub-hydric communities, marsh and bog sedges, riparian mosses, as well as dwarf shrubs such as willow.Material and methods: The first step will consist in carrying out a multi-criteria analysis with different spectral indices. This will make it possible to determine the sampling plan for the field campaigns. A morphometric analysis will make it possible to study the shapes of the lakes. Active and passive microwaves are sensitive to soil water content through the dielectric constant. In summer, water is detected but in winter, water in its frozen form is no longer detected. To produce the freeze or thaw maps, it is first necessary to determine the DOY (day of the year) on which the phase change of the water contained in the active layer occurs. The maps produced will be compared with the data collected in the field. Then, the production of time series of the different maps will reveal the evolution of the analyzed parameters.Expected results: The expected results will mainly take the form of maps: 1) maps of freeze/thaw dynamics and lakes, 2) maps of evolution of freeze/thaw dynamics (time series: seasonal, then multi-year), 3) map of geolocated field measurements and their interpolation.

Research Site Coordinates

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