Fine-Scale Spatio-Temporal Monitoring of Multiple Thermo-Erosion Gully Development on Bylot Island, Eastern Canadian Archipelago

摘要

Water infiltrating ice-wedge contraction cracks can enable the formation of tunnels in the permafrost, leading to collapse and thermo-erosion gully initiation. The valley of Glacier C-79 on Bylot Island in Canada features dozens of thermoerosion gullies, ranging from a few meters up to 2 km in main axis length. Five of the largest gullies were chosen for fine-scale spatio-temporal monitoring between 1958 and 2011 using field observations, differential GPS mapping, and aerial and satellite imagery from 1958, 1961, 1972, 1982, 2007, and 2009 to 2011. Gullies developed in aeolian, colluvial, and organic depositional environments. Two gullies were nearly stabilized while three were evolving during the 2007-2011 period at rates ranging from 14± 3 m y~(-1) to 25 ± 4 m y~(-1). One gully mouth has eroded over 82 ± 6 m in length during the last three decades by riverbank erosion. Two gullies were formed before 1958, while the other three were initiated at least after 1972 but before the current decade.