Geomorphology of a thermo-erosion gully, Bylot Island, Nunavut, Canada¹This article is one of a series of papers published in this CJES Special Issue on the theme of Fundamental and applied research on permafrost in Canada.²Polar Continental Shelf Project Contribution 043-11.

Abstract

A thermo-erosion gully has been monitored in the valley of glacier C-79 on Bylot Island since 1999. The main channel of the gully reached 390 m in length a few months after its initiation and grew between 38 and 50 m/year over the following decade, for an overall approximated average of 75 m/year. In 2009, the total gully length and area, including the main and relict channels, were 2500 m and 25 000 m2, respectively. Gullies affect snow accumulation, and therefore ground temperature, local water flow, and drainage. Sinkholes, gully heads, pools, baydzherakhi, tunnels, and collapses were grouped as a function of time since gully formation in that area. Sinkholes and tunnels were formed every year after gully inception, and baydzherakhi were found in 3–10 year old sections of the gully. Stabilization of the gully floor and sides took about a decade.

Effects of thermo-erosion gullying on hydrologic flow networks, discharge and soil loss

“…It was well demonstrated in the literature that the peak of erosion rate and enlargement of a gully occurs during the first fraction of its entire lifetime (Sidorchuk 1999). This model of evolution concord with the rates of erosion observed on R08p, with a observed erosion length of 390 m of the main axis a few month following its initiation (Godin and Fortier 2012b), down to a few dozen meters and less in the last few years ( figure 3). The two other gullies which initiated during the 1972-2007 lapse are enlarging at this time but the rate of erosion trend is slowing to a few dozen meters to a few meters per year.…”

“…Sudden, repeated or massive input of run-off water over inland polygons can trigger the formation of sinkholes and tunneling of ice wedges, leading to the formation of gully networks (Fortier et al 2007). Following inception, the rate of gully erosion can reach several 10's m per year and subsequent positive feedbacks can keep the gully active and enlarging for more than a decade (Godin and Fortier 2012b). Climatic models (Easterling et al 2000) and recent climate observations indicate that the likeliness of occurrence of extreme events (such as air temperature variability, amount of precipitations) is increasing, which favors thermokarst development (Hinzman et al 2005) and thermo-erosion gullying.…”

Remote sensing evaluation of High Arctic wetland depletion following permafrost disturbance by thermo-erosion gullying processes

“…The greatest disturbances found along the R08p and R06 gullies can be explained by the substantial lengths of the main channels and the presence of secondary channels (Godin and Fortier 2012b). The R08p gully has been expanding simultaneously on six distinct secondary channels, while the R06 gully main channel progression has been among the fastest thermo-erosion development rates in the valley (Godin and Fortier 2012a).…”

“…We first preprocessed the satellite image by applying a geographical correction based on the differential global positioning system (DGPS) coordinates of the studied gullies (Godin and Fortier 2010, 2012a, 2012b and by converting the raw digital numbers of red and near-infrared bands to Top Of Atmosphere (TOA) reflectance values (Goward et al 2003). Following cloud masking, a subset scene of the valley encompassing areas of interest was obtained by manually digitizing boundaries.…”

Quantification of upland thermokarst features with high resolution remote sensing

“…Remote sensing allows us to observe these areas in a cost-effective manner and on the timescales needed to answer questions about the rapidly changing landscape. So far, the remote detection of thermokarst has been limited to relatively large and visually distinct features, such as thermokarst lakes (Morgenstern et al 2011, Jones et al 2011, drained lake basins (Hinkel et al 2003, Wang et al 2012, retrogressive thaw slumps Pollard 2008, Lantuit et al 2012), and thermo-erosion gullies (Godin and Fortier 2012). However, to capture the true magnitude of thermokarst, it is also necessary to expand observation capabilities towards detection of small, subtle thermokarst forms.…”