Terrain and climate effects mediate change in surface water across the western Canadian Arctic and Subarctic




Travers-Smith, Hana

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Rising temperature and precipitation are driving widespread changes in the area of surface water across the Arctic and sub-Arctic. Previous work suggests that broad-scale increases in surface water area are occurring in the zone of continuous permafrost, while decreases are occurring the zone of discontinuous permafrost. However, there are still uncertainties surrounding regional change and fine-scale terrain factors that may mediate the effects of temperature and precipitation. In my MSc research I examine terrain and climatic drivers of change in the area of lakes and ponds across the western Canadian Arctic and Sub-Arctic. In the first part of my thesis I use the Landsat satellite image archive to map change in lake area within the Lower Mackenzie Plain, NWT. I found that overall lake area has largely decreased since 1985, due to the drainage of large lakes. I also found that lakes located in fire scars were more likely to show persistent decreases in area, likely due to interactions with surrounding permafrost conditions. In the second part of my thesis, I used the Global Surface Water dataset developed by the GLAD research group to model changes in total permanent water across the Northwest Territories and the Yukon. I used a Random Forest model to analyze the effects of terrain and climate variables on the direction of change in permanent water. My observations show that surface water area has generally increased, and that the response of surface water to climate change largely depends on regional geology. Increases in permanent water were more likely to occur in wetter regions underlain by bedrock or fine-colluvium while decreases were more likely to occur in warmer regions and areas underlain till blanket. I also used methods developed in the first part of my thesis to compare regional changes in surface water across six distinct study areas. I observed increases in surface water across five of the six study areas and consistent decreases in lake area associated with wildfire. This research shows that changes in surface water are complex and depend on interactions between climate variables and fine-scale terrain factors. My research also demonstrates the importance of wildfire in driving permafrost and lake dynamics.



arctic, permafrost, ecology, remote sensing, thermokarst, climate change