Audrey Veillette presents: Stabilisation post-dégradation et modification à long terme du pergélisol

February 19, 2016 in Conference, post

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Me and my poster at the Center for Northern Studies annual colloquium. Photo credit : Daniel Fortier

It is at the annual colloquium of the Center for Northern Studies (CNS), that took place in Trois-Rivières, that I presented for the first time the preliminary results of my masters’ research to a scientific public! My poster focuses on the morphological traits of a stabilized permafrost following perturbation by thermo erosion. On Bylot Island, many thermo erosion gullies incise the studied valley; the gullies remain in the landscape once stabilized, after a few decades. This stabilization generates new characteristics for surface permafrost; hence it is important to understand better the new state of permafrost. Preliminary results indicate an increased presence of ice if the upper permafrost, which modifies the quantity of latent heat in the soil, having effects on its thermal stability! For the next few weeks, I will be working in the lab to quantify this latent heat.

During the colloquim, I also had the chance to discuss about thermo erosion with the passionate François Costard, as well as learn about a variety of ongoing Nordic research work. Thanks to the CNS 🙂

 

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Contrasting patterns of thermo-erosion gullies formed in syngenetic ice wedge polygonal terrains on Bylot Island, eastern Canadian Arctic: case studies from three different sedimentary environments

November 3, 2015 in Conference

During the GeoQuebec2015 conference in Quebec city, I had to chance to present my bachelor thesis. It was my first time in a national conference and I was very happy and apprehensive to break the ice – no pun intended! The presentation was set on Monday 21st of September (15:45) during a session chaired by Sharon Smith called Characterization of Permafrost State and Variability II (205A). Here is the main abstract of the presentation: Ice wedge polygonal terrains, typical of Arctic permafrost geosystems, are vulnerable to thermo-erosional gullying and thermokarst. Gullies located on Bylot Island (NU) have distinct shapes and dynamics on factors such as their age, alluvial activity level, water balance and nature of the sedimentary environment. In this paper we focus on the contrasts differencing gullies observed in aeolian sands, colluvium/alluvium and peaty-loess deposits. Polygons areas, ice wedges size and consequently gully shapes were distinct for each environment: the peaty-loess-zone had medium-sized polygons and generally larger ice wedges, which erosion resulted in well-developed multi-channel gullies. The aeolian sands-zone had smaller polygons and thinner ice wedges, where quasi-linear gullies were formed. The colluvium/alluvium-zone had large polygons with large primary ice wedges. The erosion was concentrated, very active, and essentially restricted to the primary ice wedges. The role of the ice wedges geometry and size in the evolution of the gullies was major, putting thermo-erosion gullies as distinct landforms from gullies found in warmer, non-permafrost zones.

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Figure 1: Example of ice-wedge and surrounding permafrost degradation through thermo-erosion. Bylot island, summer of 2013. 

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Table 1: Morphologic characteristics of 4 gullies and their erosion activity pattern

 

 

If you want to know more, you can find my presentation and article on Research Gate, here are the links, enjoy!

Presentation (slideshow)

Paper (PDF)

 

 

Blog- by Audrey Veillette

August 27, 2015 in post

August 10, 2015

Two weeks after coming back from Bylot Island, it’s already time to leave for another adventure but this time, in Northern Quebec with the course UQAM NORD! We will travel on the road through Abitibi-Témiscamingue up to Radisson and then fly to Kuujjuarapik. On the schedule are a few field visits (mining site of Malarctic, La Grande hydroelectric complex), conferences and testimonials concerning diverse themes such as energy, mining, northern ecosystems, society and culture and tourism. When I will be back in September, it will finally be time to process all the data collected in Bylot Island this summer!

Myself walking in the snowy valley in May 2015 at Bylot Island

Blog – Georadar and permafrost coring (summer 2015): – by Audrey Veillette

August 20, 2015 in post

My fieldwork this summer could be described by two essential elements : a georadar and a permafrost coredrill (oh, and not to forget Vilmantas Preskienis, my precious collegue who helped me all summer to collect the data!).

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Daniel Fortier (Director of Geocryolab) and Étienne Godin (PhD candidate) are performing the firsts cores of the summer at my study site. We are looking for aggradational ice, reflecting the uplift of the permafrost table after a perturbation like thermo erosion gullying.

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Vilmantas Preskienis (PhD candidate) assembling the georadar and getting ready for a day where we will make 25 cm steps in the tundra!

Our patience was put to the test when using georadar. Over a few hundreds of meters, we surveyed the ground, making steps as small as 10 to 50 cm (depending on the antennas). The data will give us information on the morphology and cryostratigraphy of permafrost at my study site, a stabilized thermo-erosion gully.

To calibrate our georadar data and allow us to precisely characterise permafrost at my study site, a lot of coring was required this summer. Thanks to the coredrill that had its engine purring all summer and worked beautifully. Two big filled coolers were brought back to Montreal!