Estimating the extent of near-surface permafrost using remote sensing, Mackenzie Delta, Northwest Territories



The extent of near-surface permafrost, or perennially frozen ground within 3 m of the surface, was estimated for the Mackenzie River delta by determining its association with riparian vegetation communities in the field, and by subsequently mapping these vegetation communities using SPOT-5 data and the supervised maximum-likelihood classification technique. Near-surface permafrost was absent beneath willow–horsetail (Salix-Equisetum) vegetation communities on point bars and alluvial islands throughout the delta and beneath horsetail (Equisetum) communities in the southern and central delta. Near-surface permafrost was found beneath all other vegetation communities and land surface types. Multispectral SPOT-5 data were classified with overall accuracies greater than 80 per cent. Using the remotely sensed vegetation community data, near-surface permafrost was estimated to occur beneath 93 per cent, 95 per cent and 96 per cent of the land surface within the investigation areas of the southern, central and northern delta, respectively. In contrast to the most recent Permafrost Map of Canada, these results indicate that the Mackenzie Delta is part of the continuous permafrost zone. Copyright © 2009 Her Majesty the Queen in right of Canada. Published by John Wiley & Sons, Ltd.