Hillslope water tracks in the High Arctic: Seasonal flow dynamics with changing water sources in preferential flow paths

Abstract

Preferential subsurface flow paths known as water tracks are often the principal hydrological pathways of headwater catchments in permafrost areas, exerting an influence on slope physical and biogeochemical processes. In polar deserts, where water resources depend on snow redistribution, water tracks are mostly found in hydrologically active areas downslope from snowdrifts. Here, we measured the flow through seeping water track networks and at the front of a perennial snowdrift, at Ward Hunt Island in the Canadian High Arctic. We also used stable isotope analysis to determine the origin of this water, which ultimately discharges into Ward Hunt Lake. These measurements of water track hydrology indicated a glacio-nival run-off regime, with flow production mechanisms that included saturation overland flow (return flow) in a low sloping area, throughflow or pipe-like flow in most seepage locations, and infiltration excess overland flow at the front of the snowdrift. Each mechanism delivered varying proportions of snowmelt and ground water, and isotopic compositions evolved during the melting season. Unaltered snowmelt water contributed to >90% of total flow from water track networks early in the season, and these values fell to <5% towards the end of the melting season. In contrast, infiltration excess overland flow from snowdrift consisted of a steady percentage of snowmelt water in July (mean of 69%) and August (71%). The water seeping at locations where no snow was left in August 2015 was isotopically enriched, indicating a contribution of the upper, ice-rich layer of permafrost to late summer discharge during warmer years. Air temperature was the main driver of snowmelt, but the effect of slope aspect on solar radiation best explained the diurnal discharge variation at all sites. The water tracks in this polar desert are part of a patterned ground network, which increases connectivity between the principal water sources (snowdrifts) and the bottom of the slope. This would reduce soil-water interactions and solute release, thereby favouring the low nutrient status of the lake.

Impact of heat advection on the thermal regime of roads built on permafrost

“…In this case study, the road alignment is primarily perpendicular to the local hydraulic gradient ( Figure 1b), but subsurface water flow is also possible subparallel to the road embankment. Further, the macroscopic heterogeneity and anisotropy of the subsurface can also control the direction of water flow (e.g., Mackay, 1983;Paquette et al, 2017;Paquette, Fortier, & Vincent, 2018).…”

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

“…Beneath the active layer, continuous permafrost acts as a barrier that impedes deeper subsurface flow (Ge et al, 2011;Walvoord et al, 2012). Conditions in water tracks differ significantly from those in their nontrack hillslope watersheds and are characterized by a deeper active layer depth, smaller amplitude of annual soil temperature change, coarser subsurface materials (Figure 1b), thicker snowpack, and higher soil moisture and nutrient contents (Ball & Levy, 2015;Curasi et al, 2016;Harms et al, 2019;Hastings et al, 1989;McNamara et al, 1999;Paquette et al, 2018;Rushlow, 2018). Since water tracks have a higher soil moisture content and are closer to their storage capacity than are the adjacent hillslopes, it has been suggested that water tracks are one of the main source areas for runoff to downslope rivers in response to summer rainfall (McNamara et al, 1997;Rushlow & Godsey, 2017) and spring snowmelt (Paquette et al, 2018).…”

“…Conditions in water tracks differ significantly from those in their nontrack hillslope watersheds and are characterized by a deeper active layer depth, smaller amplitude of annual soil temperature change, coarser subsurface materials (Figure 1b), thicker snowpack, and higher soil moisture and nutrient contents (Ball & Levy, 2015;Curasi et al, 2016;Harms et al, 2019;Hastings et al, 1989;McNamara et al, 1999;Paquette et al, 2018;Rushlow, 2018). Since water tracks have a higher soil moisture content and are closer to their storage capacity than are the adjacent hillslopes, it has been suggested that water tracks are one of the main source areas for runoff to downslope rivers in response to summer rainfall (McNamara et al, 1997;Rushlow & Godsey, 2017) and spring snowmelt (Paquette et al, 2018). Higher liquid-water saturation in water track soils is also linked to increased solute transport (Levy et al, 2011), nutrient and carbon cycling (Ball & Levy, 2015;Cheng et al, 1998;Harms & Ludwig, 2016;McNamara et al, 2008;Oberbauer et al, 1991;, vegetation productivity (Curasi et al, 2016), and heat transfer (Gooseff et al, 2013;Hastings et al, 1989;Paquette et al, 2016Paquette et al, , 2018.…”

“…Since water tracks have a higher soil moisture content and are closer to their storage capacity than are the adjacent hillslopes, it has been suggested that water tracks are one of the main source areas for runoff to downslope rivers in response to summer rainfall (McNamara et al, 1997;Rushlow & Godsey, 2017) and spring snowmelt (Paquette et al, 2018). Higher liquid-water saturation in water track soils is also linked to increased solute transport (Levy et al, 2011), nutrient and carbon cycling (Ball & Levy, 2015;Cheng et al, 1998;Harms & Ludwig, 2016;McNamara et al, 2008;Oberbauer et al, 1991;, vegetation productivity (Curasi et al, 2016), and heat transfer (Gooseff et al, 2013;Hastings et al, 1989;Paquette et al, 2016Paquette et al, , 2018.…”

The impact of land surface temperatures on suprapermafrost groundwater on the central Qinghai‐Tibet Plateau

“…Moreover, it is evident that there are significant differences in the spatial LST distribution under different topographies, especially under different slope aspects. Paquette, Fortier, and Vincent () reported that a combination of steep topography and slope aspect can play a similar role to sunset in the energy balance at polar latitude. Carey and Woo (, , ) reported that different slope aspects exhibit large water flux variabilities as topography, microclimate, soil, frost, and vegetation vary.…”