by Sabine

Heat Advection in the Active Layer of Permafrost: Physical Modelling to Quantify the Impact of Subsurface Flow on Soil Thawing.

November 6, 2015 in Conference by Sabine

The 7th Canadian Permafrost Conference and 68th Canadian Geotechnical Conference (GEOQuébec2015) took place in Quebec City last September. On Sept. 23rd during the “Physical and Numerical Modelling in Cold Regions” session chaired by Marc Lebeau, I presented a portion of the laboratory research I have been conducting during this past year at the Geocryolab. My work has been aiming to quantify the impact of subsurface flow and surface run-off on permafrost degradation. The paper we published for this conference presents the experimental design and the data analysis methods developed for this work.

Presentation (Slideshow)

Paper (PDF)

SV-Geoqc-f4

 

Abstract :

To measure the impact of water flow on permafrost degradation, several experiments of active layer physical models were conducted in laboratory. Eight wooden cells filled with different quasi-saturated soils were subjected, for the first half, to a thawing by conduction and for the other half to a thawing by convection (water flow). The purpose of this protocol is to develop, with experimental data, tools to quantify the efficiency of thawing by conduction in comparison to thawing by convection.

Incidence of Late Pleistocene-Holocene Climate on the Concurrent Landscape and Permafrost Development of the Beaver Creek Region, Southwestern Yukon, Canada

November 5, 2015 in Conference by Sliger.M

For the 7th Canadian Permafrost Conference and 68th Canadian Geotechnical Conference (GEOQuébec2015), held in Quebec City last month (September 20-23), I presented a geomorphological model of the Beaver Creek moraine, inherited from the Mirror Creek glaciation. This model outlines five development stages of the landscape and permafrost interpreted from five cryostratigraphic units found in numerous deep boreholes. It can be used to evaluate the spatial extent of ice-rich permafrost underlying the road sitting on the moraine. My research director and co-author, Dr. Daniel Fortier, presented a talk during the session ‘Geocryology II’ on Wednesday, September 23 (Room 2105, 13:30-15:00). The full abstract appears below, and the presentation and corresponding paper are available here:

Presentation (Slideshow)

Paper (PDF)

MS-GEOQuebec2015-Figure1

Abstract

The Beaver Region is located in southwestern Yukon and was not glaciated during the last glacial advance (Late Wisconsinian, 26-11.7Ky BP). The site lies on Middle Wisconsinian to Holocene deposits covering a disintegration moraine; prior cryostratigraphic investigations have shown the presence of ice-rich cryofacies and syngenetic ice wedges down to 10 m below the surface. The objective of this paper is to propose a conceptual model linking the permafrost cryostratigraphy to the post-glacial climate history. 29 boreholes have been analysed in relation to the topography, ecology and pedology. Five cryostratigraphic units have been defined, characterized and related to specific development stages. As results, the contemporary landscape can be defined in two contrasted zones; mesic convex, and humid concave areas. This differentiated geomorphology affects the modern landscape evolution from a geothermal, hydrologic, ecologic, pedogenic and cryogenic perspective.

by Kate G.

Impact of land cover disturbance on permafrost landscapes: Case Studies from Yukon communities

November 5, 2015 in Conference by Kate G.

As part of the 7th Canadian Permafrost Conference and the 68th Canadian Geotechnical Conference (GEOQuébec 2015) held in Quebec City last September, Louis-Phillippe Roy (Yukon College) presented three case studies from our work done in Yukon communities in recent years. We found that the complete removal of vegetation cover for agriculture or mining activities had a strong impact on permafrost degradation. However, selective cutting of forested areas to prevent the propagation of forest fires had little impact, if any, on the underlying permafrost. Louis-Philippe presented during the Northern Communities session chaired by Martin Tremblay, on Wednesday September 23rd. The summary of the paper appears below, as well as links to access the presentation and the full paper.

KG-geoqc-Fig1

Figure 1: Main conclusions from the three case-studies

Abstract:

Using examples from three case studies in Yukon communities, we investigate the role of anthropogenic disturbance on permafrost landscapes. Landscape modifications investigated include alternations to surface vegetation for fire protection adjacent to communities, and land clearing to support economic activities like surface mining and agriculture. In most cases, the removal of protective vegetative cover resulted in permafrost degradation, leading to the development of near-surface taliks over decadal-scale time periods. Conversely, light alteration to vegetative cover (e.g., stand thinning for fire protection) does not appear to have altered permafrost presence or distribution. Results have implications for community-scale land use planning in the context of a changing climate.

Presentation (Slideshow)

Paper (PDF)

 

Lake bottom imagery: a simple, fast and inexpensive method for surveying shallow freshwater ecosystems of permafrost regions

November 4, 2015 in Conference by fbouchard

During the 7th Canadian Permafrost Conference and 68th Canadian Geotechnical Conference (GEOQuébec2015), held in Quebec City last month (September 20-23), I presented a novel strategy of surveying and sampling lake sediments. This method integrates modern and readily available lake bottom imagery tools (GPS-sonar and waterproof camera), and allows us to quickly map lake basins and select the best sediment coring sites for paleolimnological studies (Figure 1). The whole tool-kit can be transported and deployed in the field by a single person (Figure 2). I presented a talk during the session ‘Permafrost (Other)’ chaired by Tim Ensom on Wednesday, September 23 (15:30-15:45). The full abstract appears below, and the presentation and corresponding paper are available here:

Link to the presentation (slideshow)

Link to the paper (PDF)

FB-GEOQC-Fig1 (mapping and coring)

Figure 1. Mapping and sampling lake bottom on Bylot Island, Nunavut. (a) Satellite image showing the sampled kettle lake within a glacial valley. (b) Bathymetric map generated using a GPS-sonar system. (c) Photo of a 37-cm long sediment core collected from the deepest part of the lake. (d) Portable GPS-sonar system installed on a small zodiac.

 

FB-geoqc-Fig2 (Zodiac sherpa)

Figure 2. The ‘Zodiac Sherpa’, proudly transporting his lake-bottom imagery tool-kit across permafrost landscapes. Photo: Vilmantas Preskienis (July 2014).

 

 

 

 

 

 

 

 

 

 

 

Abstract:

Widespread and diverse in permafrost landscapes, freshwater ecosystems play a crucial role in maintaining the traditional lifestyle of northern communities as habitats for aquatic plants and wildlife, and many are also biogeochemical hotspots that strongly emit greenhouse gases. Limnological and paleolimnological studies are of great importance for understanding the past, present and future dynamics of such aquatic systems. This paper presents a novel, highly integrated lake-bottom imagery strategy for surveying lake-bottom water and sediments prior to sampling. It is user-friendly and easily portable, can be implemented rapidly in the field with directly accessible data, and is much less expensive than regular lake basin surveying techniques. The method integrates GPS-assisted sonar technology, underwater HD photo-video camera, and water depth and temperature sensors. Examples from Canadian High Arctic permafrost landscapes, where the method has been recently applied, are reported and discussed.

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 by Audrey Veillette

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.

AV-geoqc-fig1

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

AV-geoqc-table1

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)