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Terrain mapping has been successfully applied to the planning and design of linear infrastructure in North America since the 1940s. A natural extension of terrain mapping in northern regions is the interpretation and characterization of permafrost and ground ice potential. This application has become increasingly important as climate change accelerates permafrost degradation, affecting the development and maintenance of infrastructure. It is, therefore, critical to forecast changes in permafrost terrain to optimize roadway routing, design, and maintenance forecasting. The accuracy and resolution of permafrost interpretations are increased markedly when based on newly available, high-resolution digital elevation models derived from structure from motion photogrammetry and airborne LiDAR surveys, in addition to traditional aerial photography. Using these resources, we have developed a predictive mapping approach to identify permafrost terrain that is susceptible to subsidence or thaw-induced mass movements as a result of climate change or anthropogenic disturbance. We have applied this approach to proposed resource access road corridors in two permafrost settings in northern Canada: the Coffee Gold Project in unglaciated west-central Yukon and a portion of the Slave Geological Province Access Corridor in formerly glaciated Northwest Territories. Terrain mapping representing current conditions was first produced to establish the distribution of distinct terrain units and indicators of excess ground ice. We then derived predictive mapping representing the variable response of distinct permafrost terrain units to projected climate conditions or disturbance. This mapping highlights the most hazardous areas, which are commonly explained by the surficial geological setting, as a basis for optimizing geotechnical field investigations. It also informs recommendations for roadway avoidance, insulative or resilient road designs, and spatio-temporal allocation of resources for maintenance. [ABSTRACT FROM AUTHOR]

Lake shoreline erosion is caused by wind-generated waves (mechanical erosion) and, in areas of permafrost, can be compounded by thawing ground ice (thermal erosion). In southwest Yukon, erosion patterns along the shorelines of Aishihik and Canyon Lakes reflect the combined effects of climate change and lake level regulation for hydroelectricity, which began in 1975. An investigation characterizing shoreline erosion and aiming to determine the relative contributions of lake level regulation and climate change was undertaken to support an environmental and socio-economic effects assessment associated with hydroelectric facility relicensing. The investigation involved three phases: (i) compilation and review of pertinent topographic, geological, and hydrological information; (ii) helicopter- and ground-based field reconnaissance; and (iii) mapping of shoreline types, relative severity of erosion and recession from former beaches at select sites. Three types of shorelines were identified based on their distinct responses to lake level regulation and climate change. Type 1 shorelines exhibit a moderate slope of coarse-grained sediment and may contain ice-poor permafrost; they are relatively insensitive to climate change and quickly self-stabilize when exposed to higher lake levels. Type 2 shorelines typically exhibit an abruptly steep embankment of ice-rich, fine-grained sediments; they are vulnerable to recession through long-term retrogressive thaw and slumping in response to climate change and lake level regulation. Type 3 shorelines are typically low-relief and composed of fine-grained, ice-rich sediments; they are most sensitive to higher lake levels due to inundation-induced thaw. Erosion along the Type 2 and Type 3 shorelines of Aishihik and Canyon Lakes appears to be driven primarily by climatic effects, despite an anomalous peak in lake level at the onset of regulation that locally initiated and exacerbated erosion. [ABSTRACT FROM AUTHOR]