GROUNDWATER FLOW AND PERMAFROST THAW; RECENT ADVANCES IN NUMERICAL MODELING IN CRYOHYDROGEOLOGY

Siegel, as my PhD supervisor, provided great mentorship and vision by supporting my initial interests in wanting to study the interactions between groundwater and frozen ground. His support led to a key publication (McKenzie, Voss, Siegel 2007) that provided one of the first numerical groundwater models capable of simulating groundwater flow with dynamic freezing and thawing processes (e.g., variable permeability as a function of ice content, latent heat effects, etc.). The presence of permafrost (ie. perennially frozen ground) affects the movement and storage of groundwater in cold regions. There are three primary pathways by which groundwater flows in permafrost terrain: 1) above permafrost through the active zone (or supra-permafrost aquifers), 2) below permafrost (i.e., sub-permafrost aquifers), and 3) through taliks, unfrozen vertical or horizontal ‘holes’ in permafrost. With climate warming and the thawing of permafrost, these pathways become larger and more connected, increasing both the storage and flux of groundwater through the arctic waterscape. Already there is extensive evidence of this hydrologic change, such as increasing flow in arctic rivers, the disappearance or emergence of lakes, and increased carbon export. This presentation will provide an overview of how the model has been recently applied to understanding these hydrologic changes in cryohydrogeology.