Yukon – evolution of a drainage ditch near the road (Michel Sliger)

November 28, 2016 in @en, focus-en by Sliger.M

A drainage ditch was 75 cm wide right after its excavation in October 2010. Two years later, it’s almost stabilized at 4 m wide. Few rivulets continue to lead some sediments movements building micro fluvial deltas. Pioneer vegetation colonized the bottom where the water doesn’t stand still or the sediment doesn’t accumulate (Figure 1).

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Mass movement monitoring using a VX station (by Michel Paquette)

November 22, 2016 in post by Davesne.G

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Precision work. This photo was taken looking through the targeting lense of the Geocryolab Trimble VX spatial station, which has the capacity to automatically follow the prism Gautier is holding. This allows him to work alone while performing measurements at a great degree of precision (~1 mm). On this photo, Gautier is recording the position of mass movement markers, a task performed every year, in order to measure downslope displacement of material of only a few centimeters. Such a precise task requires patience, which is particularly easier to have when the weather is calm and sunny. Luckily for Gautier and Michel, the final two weeks of their 2016 field season on Ward Hunt was blessed beautiful and warm (Ward Hunt standard !) weather, perfect for long and delicate work such as this.

What is the impact of subsurface water flow on the thermal regime of the ground? (Daniel Fortier)

November 15, 2016 in @en, post by Davesne.G

In response to climate changes, permafrost thaw and active layer deepening shall favor the increase of subsurface water flow. Geocryolab designed experimental cells to evaluate the thermal ipact of groundwater on the ground thermal regime. Why? Because very few information is currently available about this topic and because laboratory study allows for a simplification of the parameters influencing the temperature and a better control of these parameters.

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Thermistor cables (left) fabricated at Geocryolab which will be linked to a datalogger (Campbell Scienific).

Influence of urbanization on permafrost (Lin Chen)

November 14, 2016 in post by Davesne.G

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The urbanization has significant influence on permafrost degradation. The degradation of permafrost in the urban area in turn has been affecting the residents’ lives, such as water supply and stability of buildings. In 2008, ground penetration radar (GPR) was conducted by Lin Chen and his teammates to investigate the influence of urbanization on permafrost.

The periglacial environment of the high summits of the Chic-Chocs Mountains (Gautier Davesne)

November 10, 2016 in post by Davesne.G

On the summits of the Chic-Chocs Mountains (North of Appalachians Range, Gaspé Peninsula) exceeding 1100 to 1200 m a.s.l., a typical periglacial environment is present. Above this elevation, only various alpine tundra species as lichens, herbs and mosses can grow on the blocky materials which characterize the ground surface (fig. 1). At Mont Jacques-Cartier (1273 m a.s.l.), the block fields, or felsenmeers, mantle a large part of the summit where the slope angle is lower than 21° (fig. 1). Over the flat surface, the blocky materials are reworked by the periglacial processes producing sorted polygons in patches where an abundant matrix of fine-grained material exists (fig. 1). On the margins of the plateau, the sorted polygons tend to stretch as the slope angle exceeds 3 to 4° to form block streams (fig. 1). Gelifluxion lobes are observable on the slopes of Mont Jacques-Cartier and Mont Albert as a result of the freeze-thaw cycle and the abundance of snowmelt water in spring (e.g. snowbed on the SE slope of Mont Jacques-Cartier). Finally, the highest summits of the Chic-Chocs Mountains present marginal contemporary permafrost bodies due to favourable azonal topoclimate conditions.

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Figure 1: Periglacial landforms observed over the Mont Jacques-Cartier plateau : A) blockstreams ; B)block fields or felsenmeers ; C) Sorted polygons.

More information in the following papiers:

Gray, J.T., Godin, E., Masse, J., and Fortier, D. (2009) Trois décennies d’observation des fluctuations du régime thermique du pergélisol dans le parc national de la Gaspésie, Le Naturaliste Canadien, 133, 69-77.

Davesne, G., Fortier, D., Dominé, F., Gray, J. (2016) Wind driven snow conditions control the occurrence of contemporary marginal mountain permafrost in the Chic-Chocs Mountains, south-eastern Canada – a case study from Mont Jacques-Cartier. The Cryosphere Discussion, doi: 10.5194/tc-2016-211.

Gray, J.T., Davesne, G., Godin, E. and Fortier, D. (2016) The Thermal Regime of Mountain Permafrost at the Summit of Mont Jacques-Cartier in the Gaspé Peninsula, Québec, Canada: A 37 Year Record of Fluctuations showing an Overall Warming Trend, Permafrost and Periglacial Processes. doi: 10.1002/ppp.1903.

 

 

Yukon – Ecological gradation (Michel Sliger)

November 8, 2016 in Article, focus-en, post by Sliger.M

The limit separating the site’s different ecosystems is generally gradual at the Beaver Creek study site (Yukon). From the ground, they are definitely unperceivable. The 6m high road embankment is a better point of view but the best one would be the neighbour hill. According to the local knowledge, the 8km walk across the muskeg to the plateau on the left of the picture take two days. The St-Elias range (the white mountains in the background) are 23km south-westward (Figure 1).

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Figure 1: Succession of ecosystem, view from the road

Differential Scanning Calorimetry (Karine Rioux)

November 4, 2016 in post by Davesne.G

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Differential Scanning Calorimetry is an advanced technology used to define the heat capacity, conductivity and thermal diffusivity of different materials.This is an essential tool to improve the understanding of heat transfer processes in soils.

Imagery by tomodensitometry (CT-Scan) of permafrost cores: a useful tool for geomorphologists (Audrey Veillette)

November 1, 2016 in post by Davesne.G

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on the left: CT-Scan Source : http://ctscan.ete.inrs.ca/; on the right: Imagery of a permafrost core obtained by tomodensitometry. We can see the orientation of air bubble in the ice rich section of the core, indication of permafrost recovery in a slope environement

The results obtained by CT-Scan imagery help us in the fine scale characterization of the cryostratigraphy of our samples. This gives us information about the formation, degradation and recovery processes of permafrost.