| Summary: | The variation in near‐surface ground‐ice content of the uppermost 1 m 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 1 m of permafrost is 34 cm. Such subsidence would substantially increase the frequency of flooding for portions of this area. Copyright © 2009 John Wiley & Sons, Ltd. and Her Majesty the Queen in right of Canada.
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