Modeling the role of preferential snow accumulation in through talik development and hillslope groundwater flow in a transitional permafrost landscape

Abstract

Through taliks-thawed zones extending through the entire permafrost layer-represent a critical type of heterogeneity that affects water redistribution and heat transport, especially in sloping landscapes. The formation of through taliks as part of the transition from continuous to discontinuous permafrost creates new hydrologic pathways connecting the active layer to sub-permafrost regions, with significant hydrological and biogeochemical consequences. 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 an anomalously deep active layer. To better understand the thermal-hydrologic controls and consequences of through taliks, we used the coupled surface/subsurface permafrost hydrology model ATS (Advanced Terrestrial Simulator) to simulate through taliks associated with preferentially distributing snow. Scenarios were developed based on an intensively studied hillslope transect on the southern Seward Peninsula, which predominately has taller shrubs midslope and tundra in upslope and downslope areas. The model was forced with detrended meteorological data with snow preferentially distributed at the midslope of the domain to investigate the potential role of vegetation-induced snow trapping in controlling through talik development under conditions typical of the current-day Seward Peninsula. We simulated thermal hydrology and talik development for five permafrost conditions ranging in thickness from 17-45 m. For the three thinnest permafrost configurations, a through talik developed, which allowed water from the seasonally thawed layer into sub-permafrost waters, increasing sub-permafrost groundwater flow. These numerical experiments suggest that in the transition from continuous to discontinuous permafrost, through taliks may appear at locations that preferential trap snow and that the appearance of those through taliks may drive significant changes in permafrost hydrology.

Development of perennial thaw zones in boreal hillslopes enhances potential mobilization of permafrost carbon

“…Current results underscore a need for advanced cryohydrogeologic models with coupled solute transport that constrain DOC, TDN, and Hg transit times to streams in the context of complex biogeochemical reactivity at ∼0°C. Continued modeling efforts to represent complexities in spatio-temporal boundary conditions that more explicitly account for the thermal and hydrologic roles of vegetation and snow as well as interannual variability in temperature and precipitation are crucial (Briggs et al 2014, Fisher et al 2016, Jafarov et al 2018. It is anticipated that subsequent site-based research will incorporate enhanced subsurface detail as well as surface-energy and water-balance information to best utilize the growing richness of data in boreal watersheds.…”

“…In response to surface warming, depth of thaw eventually exceeds depth of seasonal frost, and a perennial thaw zone (PTZ), or supra-permafrost talik, develops. Though vertical talik development beneath surface-water bodies is well established through theory and observations (Plug and West 2009, Minsley et al 2012, Wellman et al 2013, Parsekian et al 2013, Roy-Leveillee and Burn 2017 and has been linked to enhanced stream discharge from sub-permafrost flow , Jafarov et al 2018, lateral taliks in terrestrial landscapes and their potential role as conduits for groundwater and solute transport are less studied. Early work focused on characterizing large lateral taliks associated with aufeis (icings) formation (Boikov et al 1984).…”

Water Tracks Enhance Water Flow Above Permafrost in Upland Arctic Alaska Hillslopes

“…where S * L is the scaled liquid water saturation that is equal to SL−Su 1−Su . In addition to the parameterization used here, there are other approaches for representing changes in permeability with freezing and thawing including the van Genuchten soil water curve (Painter, 2011;Painter et al, 2016), physically derived models where parameters depend on total water content (Jafarov et al, 2018;Painter & Karra, 2014), and others described by Kurylyk and Watanabe (2013). Please see section 5.4 for a discussion of model limitations.…”

Soil Physical, Hydraulic, and Thermal Properties in Interior Alaska, USA: Implications for Hydrologic Response to Thawing Permafrost Conditions

“…The active layer can be defined as the zone that seasonally freezes and thaws (e.g., Walvoord & Kurylyk, ). Impacts of thawing and degrading permafrost include shifts in lateral and vertical water fluxes and changes in water residence time (Jafarov et al, ; Lamontagne‐Hallé et al, ; Lyon & Destouni, ; St Jacques & Sauchyn, ; Walvoord et al, ; Walvoord & Striegl, ), which in turn alter fluxes of dissolved organic matter and mineral weathering products (e.g., Koch et al, ; Striegl et al, ). Permafrost‐thaw induced changes in infiltration and drainage influence soil moisture, promoting thermal feedback.…”

“…Recent cryohydrogeologic modeling efforts have made considerable progress in understanding the most important factors and consequences of changes in permafrost and active layer thickness driven by climate and disturbance shifts. These modeling studies have demonstrated the sensitivity of permafrost table depths to organic layer thickness, vegetation, and snow properties (e.g., Atchley et al, 2016;Briggs et al, 2014;Jafarov et al, 2018;Lamontagne-Hallé et al, 2018;Walvoord et al, 2019); soil thermal properties (e.g., Hinzman et al, 1998); soil saturation (e.g., Chadburn et al, 2015;Rawlins et al, 2013;Subin et al, 2013); soil physical properties such as bulk density and porosity (e.g., Harp et al, 2015;Zipper et al, 2018); soil hydraulic properties such as soil permeability (e.g., Zipper et al, 2018); and parameters such as residual water content (Harp et al, 2015). Recent modeling efforts have simulated unsaturated freeze/thaw dynamics (e.g., Briggs et al, 2014;Lamontagne-Hallé et al, 2018), which requires soil-water retention curve specification.…”