Evaluation of RADARSAT-2 DInSAR Seasonal Surface Displacement in Discontinuous Permafrost Terrain, Yellowknife, Northwest Territories, Canada

Differential Interferometric Synthetic Aperture Radar (DInSAR) is an increasingly viable method for assessing permafrost terrain stability, but the accuracy and performance within discontinuous permafrost terrain has not been well studied. We used a RADARSAT-2 DInSAR data stack for a 120-day period in the summer of 2010 to map seasonal surface displacement in the discontinuous permafrost terrain of Yellowknife, Northwest Territories. Calculated displacement was compared to surficial geology and municipal land use zones. Displacement results reveal that glaciofluvial, glaciolacustrine, humanly modified, and organic terrain are increasingly unstable, in contrast to predominantly stable bedrock. Within municipal zones, increased proportional displacement is related to higher proportions of glaciolacustrine sediments and organic terrain. Organic terrain, associated with the highest proportion of the moderate downward displacement (−3.0 cm to −6.0 cm), occupies less than 6% of the total area. Widespread glaciolacustrine sediments (30% total area) are associated with most of the downward displacement in municipal zones. Semi-quantitative field and geotechnical validations indicate that most areas of moderate seasonal downward displacement in developed areas also represent areas of long-term subsidence. This work shows that even a short InSAR data stack and a simple stack processing method can yield information that is useful for municipal knowledge and planning.