Thaw settlement susceptibility mapping for roads on permafrost - Towards climate-resilient and cost-efficient infrastructure in the Arctic

Permafrost thaw induces terrain instabilities and hazards that severely threaten the integrity of roads and, by extension, the socioeconomic development of Arctic communities. The research aimed at identifying paved road sections currently susceptible to permafrost thaw settlements and their damages, in Ilulissat, West Greenland. To this end, we developed and implemented a Thaw Settlement Susceptibility Index (TSSI) and a mapping framework relying upon the qualitative assessment of hazard sources, infrastructure vulnerability, and impacts of permafrost-induced failures. Our evaluation was principally based on the combination of geotechnical data (including 1127 digitized borehole logs and a high-resolution inventory of road conditions) with remotely sensed ground surface displacement maps. We found that 39% of the roads assessed in Ilulissat were established on highly hazardous terrains, characterized by the presence of fine-grained frost-susceptible sediments, severe water ponding, and/or snow ploughing accumulations. Respectively, 9 and 3% of the road network were evaluated as vulnerable to thaw settlements and severely impacted. Overall, we showed that 12% of paved roads established on sediments were highly susceptible to permafrost thaw settlements and may consequently require greater resources to be maintained. Our study illustrated the potential of hazard and susceptibility maps, produced at the community scale, to support infrastructure risk management and optimization of local resources. Future work will be dedicated to assessing the susceptibility of existing roads and unbuilt terrains to permafrost thaw settlements under projected climate scenarios.