Characterization of hydrological processes of a glaciarized watershed catchment in Canadian St. Elias Mountains using natural tracers

Abstract

Changes in the hydrological processes of alpine glacierized watersheds have been observed in most regions of the world. These have an important impact on water resources and can affect downstream ecosystems and populations. Subarctic catchments such as those found in southern Yukon (Canada) are particularly sensitive to climate related hydrological changes. To further understand the ongoing evolution of subarctic hydrological systems, we applied natural tracers based investigations in the Saint-Elias mountain range of the Yukon. Our study site consisted of a small watershed, named B for logistical reasons, of the upper Duke watershed. B watershed contains three small glaciers numbered B1 to B3 from largest to smallest. The main goal was to identify water sources using hydrochemical signatures and their relative contributions to outflows in the catchment as well as using the method to identify sources contributing during the diurnal cycle. During the summer of 2015, extensive sampling of watershed B resulted on a spatial analysis of all three glaciers and a temporal analysis on the entire watershed. Samples were analyzed for organic carbon, major ions and heavy stable water isotopes (δ18O and δ2H). The resulting dataset was then processed using statistical methods and the hydrochemical basin characterization method (HBCM) for a qualitative and quantitative analysis. In this study, end-members were separated using pH, electrical conductivity, potassium, magnesium and sulfate concentrations. Results show that on the sampling period, watershed outflows consisted mainly of glacier meltwater with a non-negligible contribution of other water sources such as ice-cored moraines. B1 glacier was found contributing 59.43% at low temperature and radiation and 69.06% during a high temperature and radiation day, while inversely B2 and B3 combined contribution were 35.66% and 29.89% during those days. The use of HBCM on samples collected over the diurnal cycle was an experimental approach; it showed positive results separating glacial and non-glacial sources. The HBCM proved to be successful in the B valley, and therefore present a high possibility of success for the hydrochemical characterization of the entire upper Duke watershed.

Date	17 Oct 2016
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Michel Baraër (Supervisor)