Profile

Gaël Machemin
Master student
Department of Applied Geomatics
University of Sherbrooke
Gael.Machemin@usherbrooke.ca

Supervised by:

Frédéric Bouchard (Regular member)

Co-supervised by:

David Didier (Regular member)

Research project description

Characterization of Early Signs and Impacts of Permafrost Degradation on Aquatic Ecosystems in a High Arctic Site

Introduction: Accelerated climate change in the Arctic is leading to permafrost degradation, which has consequences for natural ecosystems, infrastructure, and local communities. My study site, characterized by continuous permafrost and numerous lakes, will be analyzed to identify early signs of permafrost degradation and to characterize the impacts of permafrost degradation on aquatic ecosystems. In this context, my Master's thesis, which is focused on identifying early signs of this degradation, will be carried out using geomatics tools.Objectives: My first objective is to characterize the morphology of inland and coastal water bodies and examine their hydrological connectivity to identify areas where sediment transport and erosion are predominant. The use of geospatial data and aerial photography acquired by drones will help achieve this objective. My second objective is to study hydrological connectivity and lake bathymetry (using sonar). With this information, I will be able to assess the consequences of permafrost degradation on these lake ecosystems.Study sites: The study site encompasses a series of coastal and inland lakes located west of Lake Kitigaq, approximately forty kilometers from Ikaluktutiak (Cambridge Bay) in Nunavut. These lakes exhibit a large variability in terms of physicochemical properties and morphology. Most of these lakes are very shallow (1-2 m) and turbid (suspended mineral matter), although some others, with clearer water, reach depths up to 12 m.Material and methods: We conducted an exploratory field campaign in 2023, during which we employed geomorphological and applied geomatics (remote sensing) techniques to collect data. Bathymetric mapping of the lakes from upstream to downstream will be carried out in 2024 using high-resolution sonar. In addition, aerial photographs taken by drones and satellite imagery will be used to quantify variations in erosion sensitivity surfaces and their impacts on permafrost. Laboratory monitoring and analysis of limnological properties of the lakes (temperature, conductivity, pH, nutrients, etc.) will allow us to assess the impacts on lake stability.References: Ayala-Borda P et al. (2021). Evidence of eutrophication in Arctic lakes. Arctic Science, 7, 859-871. https://doi.org/10.1139/as-2020-0033 Box JE et al. (2019). Key indicators of Arctic climate change: 1971–2017. Environ. Res. Lett., 14, 045010. https://doi.org/10.1088/1748-9326/aafc1b Tank SE et al. (2020). Landscape matters: Predicting the biogeochemical effects of permafrost thaw on aquatic networks with a state factor approach. Permafr. Periglac. Process., 31(3), 358-370. https://doi.org/10.1002/ppp.2057 Smith SL et al. (2022). The changing thermal state of permafrost. Nat. Rev. Earth Environ. 3, 10-23. https://doi.org/10.1038/s43017-021-00240-1 Tuia D et al. (2021). Toward a Collective Agenda on AI for Earth Science Data Analysis. IEEE Geosc. Rem. Sens. Mag., 9, 88-104. https://doi.org/10.1109/MGRS.2020.3043504 Walvoord MA and Kurylyk BL (2016). Hydrologic Impacts of Thawing Permafrost – A Review. Vadose Zone Journal, 15(6), 1-20. https://doi.org/10.2136/vzj2016.01.0010

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