Quantifying the contribution of glacier runoff to streamflow in the upper Columbia River Basin, Canada

• Published in: Hydrology and Earth System Sciences
• Main Authors: G. Jost, R. D. Moore, B. Menounos, R. Wheate
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2012
• Subjects: Technology; T; Environmental technology. Sanitary engineering; TD1-1066; Geography. Anthropology. Recreation; G; Environmental sciences; GE1-350; Canada; Nash; Sutcliffe; glacier*
• Online Access: https://doi.org/10.5194/hess-16-849-2012; https://doaj.org/article/b0c82ea0a9024ecaa47572be3ac9e6ca

Glacier melt provides important contributions to streamflow in many mountainous regions. Hydrologic model calibration in glacier-fed catchments is difficult because errors in modelling snow accumulation can be offset by compensating errors in glacier melt. This problem is particularly severe in catchments with modest glacier cover, where goodness-of-fit statistics such as the Nash-Sutcliffe model efficiency may not be highly sensitive to the streamflow variance associated with glacier melt. While glacier mass balance measurements can be used to aid model calibration, they are absent for most catchments. We introduce the use of glacier volume change determined from repeated glacier mapping in a guided GLUE (generalized likelihood uncertainty estimation) procedure to calibrate a hydrologic model. This approach is applied to the Mica basin in the Canadian portion of the Columbia River Basin using the HBV-EC hydrologic model. Use of glacier volume change in the calibration procedure effectively reduced parameter uncertainty and helped to ensure that the model was accurately predicting glacier mass balance as well as streamflow. The seasonal and interannual variations in glacier melt contributions were assessed by running the calibrated model with historic glacier cover and also after converting all glacierized areas to alpine land cover in the model setup. Sensitivity of modelled streamflow to historic changes in glacier cover and to projected glacier changes for a climate warming scenario was assessed by comparing simulations using static glacier cover to simulations that accommodated dynamic changes in glacier area. Although glaciers in the Mica basin only cover 5% of the watershed, glacier ice melt contributes up to 25% and 35% of streamflow in August and September, respectively. The mean annual contribution of ice melt to total streamflow varied between 3 and 9% and averaged 6%. Glacier ice melt is particularly important during warm, dry summers following winters with low snow accumulation and early snowpack ...