A three-dimensional groundwater flow simulation of Granger Basin, Yukon, Canada

Groundwater flow and exfiltration (discharge) in Arctic and Subarctic mountain regimes is poorly understood yet plays an important role in areas underlain by continuous and discontinuous permafrost. Permafrost, ground with a perennial temperature below 0°C, acts as an impermeable barrier to groundwater flow and influences hydrogeologic connectivity and storage. The Arctic is warming at twice the global average rate, leading to rapid permafrost thaw with unclear consequences for groundwater systems. In this study, we develop a numerical groundwater model of the Granger Basin, Yukon, to further our understanding of the influence of permafrost and thaw on groundwater flow in basins impacted by climate change.

Granger Basin is a 7.6 km²  headwater catchment located within the Wolf Creek Research Basin, Yukon, Canada. It is representative of a subarctic-continental mountain environment with already observable climate change impacts. To date, there has been limited hydrogeology monitoring or numerical modeling at this site. To investigate cryohydrogeologic processes within the basin, we integrate existing field data, including 30 years of hydrometeorological records and geophysical data into a three-dimensional numerical model with saturated-unsaturated groundwater flow. We use the SUTRA-ice numerical model that couples groundwater flow and energy transport with dynamic freeze-thaw processes. The model incorporates both time-dependent thermal and hydrological surface boundary conditions and is used parametrically to understand the generation of groundwater baseflow in this setting. We will present initial results that will evaluate the impact of different hydrogeologic properties on the generation of groundwater streamflow in Wolf Creek, how permafrost in transition affects the groundwater system, and provide the framework for future research directions.