Hillslope hydrological linkages: importance to ponds within a polar desert High Arctic wetland

摘要

Arctic wetland environments are considered to be sensitive to ongoing climate change but they have received limited attention despite their ecological importance. To understand and quantify better the hydrologic processes which are leading to the sustainability and demise of High Arctic ponds, a water balance framework was employed on several ponds situated in two broad geomorphic areas near Creswell Bay, Somerset island (72°43'N, 94°15'W). These ponds are also linked to an upland area through a range of linear features: stream, late-lying snowbeds and frost cracks. This study assesses the importance of these features with respect to the sustainability of these wetland ponds. A pond's position in the moraine landscape was important in determining its connectivity to a nearby stream and late-lying snowbed. Close proximity to a stream draining a large upland snow-covered catchment ensures steady water levels during the snowmelt period. Once discharge slows, a late-lying snowbed continues to supply the pond and others nearby with meltwater. The deeply thawed, sandy coastal zone is characterized by frost cracks, which contribute to the patterned ground of this wetland zone. These cracks, when situated downslope of ponds, function primarily as 'sinks' and serve to deprive small and medium-sized ponds of water during dry periods, often leading to their desiccation.