Predictive Mapping of the Variable Response of Permafrost Terrain to Climate Change for Optimal Roadway Routing, Design, and Maintenance Forecasting in Northern Canada

摘要

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.