Sustainability of High Arctic Ponds in a Polar Desert Environment

Abstract

AbStRACt. Arctic wetland environments are sensitive to ongoing climate change as seen by the recent loss of lakes and ponds in southern Alaska, Siberia, and northern Ellesmere island, Canada. A clearer picture of the mechanisms accounting for these losses or the persistence of ponds is presently required. to better understand and quantify the hydrologic processes that are leading to the sustainability or demise of High Arctic ponds, a detailed study was conducted during the summer seasons of 2006 at Somerset Island, Nunavut (72˚43' N, 94˚15' W). A water balance framework that quantifies water inputs, losses, and storage was employed on four ponds situated in three broad geomorphic areas (coastal, bedrock, and glacial terrain, which includes plateau and moraine). The initial snow cover amount influenced the water level pattern for the summer season. Large end-of-winter snow accumulations in the deep bedrock pond ensured large initial water storage and seasonal sustainability despite variable climatic conditions and a coarse substrate, which encouraged subsurface outflow. Connectivity to a stream draining an upland area and a melting late-lying snowbed nearby allowed the small Moraine pond to maintain stable water levels throughout both years. Sandy soils typical of the Coastal and Plateau ponds favored seepage and subsurface water losses, leading to desiccation of these ponds during dry periods. Lateral water losses from the Coastal pond were enhanced by the presence of a downslope frost crack that formed a steep hydraulic gradient with the pond. High initial snowfall and substantial rain maintain pond water levels, but in years with low snowfall and dry conditions, ponds are vulnerable to disappearance unless a range of dependable hydrological linkages exists.Key words: Arctic hydrology, climate change, connectivity, low-gradient wetland, sustainability RÉSuMÉ. Les milieux humides de l'Arctique sont sensibles aux changements climatiques continus, tel que l'atteste la perte récente de lacs et d'étangs du sud de l'Alaska, de la Sibérie et du nord de l'île d'Ellesmere, au Canada. À l'heure actuelle, il faut obtenir une meilleure idée des mécanismes à la source de ces pertes ou à la source de la persistance des étangs. Afin de mieux comprendre et de quantifier les processus hydrologiques qui entraînent la durabilité ou la disparition des étangs de l'Extrême arctique, une étude détaillée a été réalisée au cours des étés 2005 et 2006 à l'île Somerset, au Nunavut (72˚43' N, 94˚15' O). À quatre étangs situés dans trois grandes zones géomorphologiques (côtière, roche de fond et terrain glaciaire, ce qui comprend plateaux et moraines), on a utilisé un cadre de référence de bilan hydrique quantifiant les gains, les pertes et le stockage d'eau. La quantité de couverture de neige initiale exerçait une influence sur le modèle de niveau d'eau pendant la saison d'été. Les fortes accumulations de neige en fin d'hiver dans la profonde roche de fond des étangs donnaient lieu à un important stockage initial de l'eau et à la durabi...

Snow cover variability at Polar Bear Pass, Nunavut

“…Locally, shallow snowpacks exist across ponds, wet meadow and plateau sites in relation to deeper snow found in incised valleys and in lee of slopes where late-lying snowbeds occur. This is similar to other high arctic studies, though snow depth, density, and SWE values at PBP are more typical of polar oasistype landscapes (e.g., Woo and Guan 2006) than polar desert areas (e.g., Yang and Woo 1999;Abnizova and Young 2010), indicating that a shift in snowpack properties is now underway at PBP. During snowmelt, shallow snowpacks exhibit frequent, small melt events (ca., 5 mm/day) in contrast to deeper snowbeds (>25 mm/day).…”

“…Melt contributions due to the precipitation flux (rain-on-snowmelt, Q p ) are still limited in this landscape despite their importance in other arctic locations, such as maritime sites (Young et al 2006;Hansen et al 2014). Overall, daily melt patterns at PBP are similar to other high arctic landscapes Woo and Guan 2006;Abnizova and Young 2010) and serve to shape snow cover depletion patterns. Fig.…”

Snow cover and snowmelt of an extensive High Arctic wetland: spatial and temporal seasonal patterns

“…In 2009 only, temperature sensors were located at the bottom of late-lying snow beds on both the northern and southern slopes of PBP at depths of 0.8 and 0.6 m, respectively. Temporal snowmelt patterns were then tracked by Stowaway temperature sensors (±0.1 • C) to provide an indication of the timing and duration of the snowmelt period (Abnizova and Young 2010). A distinct change in temperature occurs when a snowpack becomes isothermal (0 • C), and again when the area becomes snow-free, as temperatures become equivalent to the air temperature.…”

“…In some regions, conditions favourable for the development of freshwater ecosystems such as wetlands can be found (Abnizova and Young 2010). The majority of the wetlands are small (tens of square metres in area) and consist of patchy strips of vegetation.…”

“…The source of freshwater to an extensive wetland may come from a variety of sources such as precipitation (rain/snow), streamflow, overland seepage from ponds and lakes and ground ice melt (Abnizova and Young 2010). Generally, the most important and largest source of freshwater occurs during spring snowmelt (Pohl et al 2005) which often recharges wet meadows, ponds, lakes and streams.…”