Near-surface ground-ice distribution, Kendall Island Bird Sanctuary, Western Arctic Coast, Canada
The variation in near-surface ground-ice content of the uppermost 1m of permafrost was examined by drilling at 71 sites within the Kendall Island Bird Sanctuary of the outer Mackenzie Delta, Northwest Territories. Permafrost has aggraded in coastal low-lying alluvial wetlands during the last 1500 to 500 years, and high near-surface ground-ice contents have developed in this saturated environment. In contrast, the ground ice in upland terrain has accumulated since the early Holocene. Permafrost in these uplands has a mean excess-ice content of 24%, lower than in the alluvial wetlands (34%), and ground-ice distribution is inherently more variable in upland terrain than in lowlands. Gravimetric moisture content is statistically related to soil organic-matter content, but the organic-matter content confounds the relation between gravimetric moisture and excess-ice content due to its low bulk density. Topographically controlled moisture availability and soil organic-matter content are important to ground-ice distribution in uplands, given the order of magnitude increase in gravimetric moisture contents downslope, and the occurrence of massive ice lenses over 50 cm thick at the base of slopes. The potential mean subsidence of alluvial wetlands due to thawing of the uppermost 1m of permafrost is 34cm. Such subsidence would substantially increase the frequency of flooding for portions of this area.
|Keywords||Ground ice, Mackenzie Delta, Permafrost, Thermokarst subsidence|
|Journal||Permafrost and Periglacial Processes|
Morse, P.D., Burn, C, & Kokelj, S.V. (2009). Near-surface ground-ice distribution, Kendall Island Bird Sanctuary, Western Arctic Coast, Canada. Permafrost and Periglacial Processes, 20(2), 155–171. doi:10.1002/ppp.650