| Popis: |
Infrastructure construction on permafrost is challenging. Not only are northern regions undergoing a faster and more intense global warming than the rest of the world, inducing thawing of the permafrost at a global scale. In addition, linear infrastructures such as gravel highways built on embankments to protect the underlying permafrost favor snow accumulation and produces dust, which can enhance permafrost degradation. The objective of this study was to use satellite (Landsat) and repeat airborne laser scanner observations to explore the physical parameters that drive permafrost degradation in the regions adjacent to the Inuvik to Tuktoyaktuk Highway (ITH) in Northwest Territories, Canada. To test if snow accumulates next to the road, we used digital elevation models produced from airborne laser scanner data collected on one snow free day in August 2018 and one as the landscape was snow covered in April 2019 over a 3 km road segment located close to Trail Valley Creek (TVC). The zone of enhanced snow accumulation was within 47 m from the road, with maximum snow depths of 1.2 m occurring directly next to the road. The area beyond 47 m was undisturbed with average snow depths of 0.4 m. Despite this finding, our analysis of Landsat images using the normalized difference snow index to discriminate between snow covered and snow-free areas show that the areas next to the road became snow-free earlier in spring than the areas further away. The road construction affected the region in close proximity the most, and the impact decreased with distance from the road to about 400 m. Increased snow cover will increase the thermal insulation as well as produce higher melt water and likely promote permafrost degradation at present and in the future of the newly constructed highway. Moreover, earlier melting may trigger other ecological feedbacks such as early greening of the tundra on the long term, highlighting the importance for more observations and additional measurements along the highway. |
