https://doi.org/10.1029/2025JF008989

Conway-White, O., Steelman, C. M., Smiarowski, A., & Rudolph, D. L. (2026). Revealing permafrost continuity across a northern watershed with airborne electromagnetics. Journal of Geophysical Research: Earth Surface, 131, e2025JF008989. https://doi.org/10.1029/2025JF008989

Permafrost thawing in northern regions may alter groundwater-surface water dynamics, thereby impacting hydrologic and ecologic functions and the potential release of stored solutes including carbon. Here, we present an airborne frequency-domain electromagnetic survey over a discontinuous permafrost region within the Central Mackenzie Valley in the Northwest Territories, Canada. Electrical resistivity measurements within the upper 100 m were gathered across a geologically complex environment where permafrost variability is hypothesized to be impacting the groundwater-surface water system. Comparison of direct permafrost observations from boreholes with airborne resistivity measurements enabled identification of frozen conditions at a regional scale within surficial sediments and bedrock. Observed variability in permafrost beneath waterbodies indicated probable direct hydraulic connectivity between surface water, unconsolidated sediments, and bedrock. Despite the absence of permafrost below these features, relatively continuous permafrost is interpreted immediately adjacent to the shore of lakes as well as along the banks of some sections of the expansive Mackenzie River. The maximum thickness of permafrost within bedrock is shown to vary from non-existent to the bottom of the resistivity model (>100 m below ground surface). Bedrock permafrost variability may be influenced by groundwater flow pathways (i.e., fracture intensity and joint patterns) controlled by the structural geology of the area. High-resolution investigations of permafrost occurrence, including within bedrock, are critical in understanding the effects of its enhanced degradation due to warming climatic conditions within northern landscapes.

In northern areas, ground that is frozen year-round–known as permafrost–blocks water flow, directing its movement on both the surface and within the ground. As the climate warms, thawing of permafrost will change the flow characteristics of water systems and contribute to changes in the landscape and habitat in these regions. Detailed mapping of permafrost is needed to understand these changes. Here, permafrost is mapped using an airborne geophysical instrument that measures the electrical conductivity of the earth. Because frozen ground is less conductive than unfrozen ground, we can infer the extent of permafrost below the ground surface using the geophysical method. We compare the distribution of permafrost to the locations of different surface water features and across different soils and rock types. This information can help us understand how varying landscapes influence permafrost distribution and water circulation. We find that permafrost is generally absent below lakes, enhancing the connection between groundwater and surface water in these locations. We suspect that variable geologic conditions also influence the distribution of permafrost. Our results will help northern communities tasked with managing water resources and understanding habitat changes due to climate warming.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JF008989