An Isotopic and Geochemical Study of Seasonal Snowmelt Runoff in the Apex River Watershed

Abstract

Few, if any, studies have used isotopic tracers to examine the seasonal snowmelt runoff in areas underlain by permafrost. we used mass balance techniques for natural oxygen-18 and several chemical parameters (electrical conductivity, Ca, Mg, K, Na, and pH) to estimate the magnitude and timing of the “old” water contribution to 1983 snowmelt runoff in the Apex River watershed. The Apex River catchment is located in the southern part of Baffin Island, Northwest Territories, Canada, where the permafrost is continuous and the active layer is less than 1 m thick. The watershed, with an area of 60 km², is dominantly Precambrian gneiss outcrop with sporadic, thin, glacial overburden. The isotopic data indicate that for the 1983 snowmelt season (third highest of eleven years of record), approximately 50% of the peak stream discharge and about 60% of the entire 1983 stream discharge was “old” water. The chemical parameters give “old” water contributions which are at least 10% less than the isotopically-derived estimate, but they are consistent with the isotopic data during peak flow. These results are not entirely consistent with the conclusions from many earlier snowmelt studies which have been based primarily on hydrometric observations.