ABSTRACT: Snow cover distribution and melt across a High Arctic wetland, Polar Bear Pass, Nunavut.

CGRG Bibliography of Canadian Geomorphology
Search Results

Author :

Date :

Title :

Publication :

Issue :

Page(s) :

Abstract

Extensive high arctic wetlands are areas of lush vegetation cover in an otherwise barren arctic landscape. They help to store and cleanse water and are critical ecosystems for arctic wildlife such as migratory birds, caribou and muskoxen. To date, an understanding of the hydrology of these regions has eluded us but we need to better understand how these extensive wetlands will sustain themselves under both shifting climatic conditions (warm/dry; cool/wet seasons) and eventually a warmer climate. Snow is considered the predominate input of water to most hydrological systems in the north. This study examined the end-of-winter snow cover and spring melt of a High Arcticwetland ecosystem located at Polar Bear Pass, Bathurst Island, Nunavut (98o 30’ W, 75o 40’ N) from mid-May until July, 2008. This wetland (ca. 20 km x 5 km) is composed of a myriad of terrain-types (ponds, lakes, wet meadows) and is bordered by rolling hills. Late-lying snowbeds occur in the lee of slopes and small and large steam channels dissect the bordering hills. Snow surveys were conducted across the different terrain types, and both snow depth and density was measured along a series of transects in order to determine the end-of-winter snowcover (snow water equivalent unitsmm, SWE). Ablation sites were established at representative sites (pond, wet meadow, late-lying snowbed, plateau) and daily estimates of snow surface lowering along with surface snow density measurements allowed surface melt to be quantified. In addition, a physically-based snowmelt model was used to define the daily melt and to examine the spatial melt pattern across the different terrain units and hillslope stream channels. End-of-winter snowcover on the ponds ranged from 28 to 73 mm. Lake snowcover was comparable at 52 mm. Deepest snowcover occurred at the sheltered late-lying snowbed sites (129 mm) and incised stream channels (59 mm). Spring 2008 was cool (avg. Tair = 2.5°C)and melt did not begin until June 9 and persisted for about 20 days. Good agreement between modelled and measured melt indicate that exposed areas with little snow (plateau zones) and windswept ponds melted out earlier (June 17, 2008), while sheltered areas (late-lying snowbed sites) and stream channels melted out 10 days later. Accurate estimates of snowcover and melt are required for assessing the water budget of this wetland system both at the local (pond) and the regional scale. Our plans for 2009 include expanding oursnow survey to other areas in the pass and defining more clearly the link between climate and snowmelt across the wetland.

Bibliography of Canadian Geomorphology