Permafrost Terrain Dynamics and Infrastructure Impacts Revealed by UAV Photogrammetry and Thermal Imaging

• Published in: Remote Sensing
• Main Authors: Jurjen van der Sluijs, Steven V. Kokelj, Robert H. Fraser, Jon Tunnicliffe, Denis Lacelle
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2018
• Subjects: anthropogenic disturbance; ground ice; landscape dynamics; thaw slump; thermokarst; stratigraphy; time series; digital terrain model; Science; Q; Northwest Territories; Canada; Ice; permafrost; Thermokarst
• Online Access: https://doi.org/10.3390/rs10111734; https://doaj.org/article/fa13fc584a1140ada2c0d53ee505842c

Unmanned Aerial Vehicle (UAV) systems, sensors, and photogrammetric processing techniques have enabled timely and highly detailed three-dimensional surface reconstructions at a scale that bridges the gap between conventional remote-sensing and field-scale observations. In this work 29 rotary and fixed-wing UAV surveys were conducted during multiple field campaigns, totaling 47 flights and over 14.3 km 2 , to document permafrost thaw subsidence impacts on or close to road infrastructure in the Northwest Territories, Canada. This paper provides four case studies: (1) terrain models and orthomosaic time series revealed the morphology and daily to annual dynamics of thaw-driven mass wasting phenomenon (retrogressive thaw slumps; RTS). Scar zone cut volume estimates ranged between 3.2 × 10 3 and 5.9 × 10 6 m 3 . The annual net erosion of RTS surveyed ranged between 0.35 × 10 3 and 0.39 × 10 6 m 3 . The largest RTS produced a long debris tongue with an estimated volume of 1.9 × 10 6 m 3 . Downslope transport of scar zone and embankment fill materials was visualized using flow vectors, while thermal imaging revealed areas of exposed ground ice and mobile lobes of saturated, thawed materials. (2) Stratigraphic models were developed for RTS headwalls, delineating ground-ice bodies and stratigraphic unconformities. (3) In poorly drained areas along road embankments, UAV surveys detected seasonal terrain uplift and settlement of up to 0.5 m (>1700 m 2 in extent) as a result of injection ice development. (4) Time series of terrain models highlighted the thaw-driven evolution of a borrow pit (6.4 × 10 5 m 3 cut volume) constructed in permafrost terrain, whereby fluvial and thaw-driven sediment transfer (1.1 and 3.9 × 10 3 m 3 a −1 respectively) was observed and annual slope profile reconfiguration was monitored to gain management insights concerning site stabilization. Elevation model vertical accuracies were also assessed as part of the case studies and ranged between 0.02 and 0.13 m Root Mean Square Error. ...