Modeling the role of vegetation-induced preferential snow accumulation in open talik development and hillslope groundwater flow in a transitional permafrost landscape
Open taliks, thawed zones extending through the entire permafrost layer play a critical thermal hydrologic role in water redistribution and heat conductance anomalies, which are likely amplified in sloping landscapes. Open taliks develop new pathways allowing to transport carbon previously stored in permafrost. At hilly field sites in the southern Seward Peninsula, AK, patches of deep snow in tall shrubs are associated with higher winter ground temperatures and anomalously deep active layer. We used the coupled surface/subsurface permafrost hydrology model ATS (Advanced Terrestrial Simulator) version 0.86 to model open talik formation by preferentially distributing snow depth along the surface of an inclined (hillslope) modeling domain. Based on an intensively studied transect of the Next Generation Ecosystems Experiment–Arctic’s (NGEE Arctic’s) Teller field site, which predominately has taller shrubs midslope and tundra in upslope and downslope areas, we investigate the effect of preferentially distributing snow along the midslope of the model domain. We forced the model with de-trended meteorological data to investigate the rate and depth of talik formation under the deeper snow applied to the mid-slope region. To better understand permafrost spatial heterogeneity along the hillslope at Seward Peninsula we simulated talik development for five permafrost conditions ranging in thickness from 17m to 45m. For the three thinnest permafrost thicknesses, an open talik developed which allowed water from the seasonally thawed layer into sub-permafrost waters, increasing sub-permafrost groundwater flow. This work indicates that variability in snow depth due to landscape properties can drive significant changes in permafrost hydrology.