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

Abstract

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. We also explicitly account for changes in glacier area through the calibration and test periods. The 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. 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, and is particularly important during periods of warm, dry weather following winters with low accumulation and early snowpack depletion. The approach introduced in this study provides an effective and widely applicable approach for calibrating hydrologic models in glacier fed catchments, as well as for quantifying the magnitude and timing of glacier melt contributions to streamflow

Glacier Meltwater Contributions and Glaciometeorological Regime of the Illecillewaet River Basin, British Columbia, Canada

“…Our results provide preliminary estimates of glacier contributions to streamflow in the basin, broadly consistent with the hydrological modelling results of Jost et al (2012), which assess a neighbouring basin with similar glacier extent. Glacier contributions to Illecillewaet Basin averaged 112 ± 12 × 10 6 m 3 from 2009 to 2011, with 66% of this from seasonal snow and 34% from glacier ice and firn.…”

“…Glacier melt also has a cooling effect on streams because of the colder meltwater and higher flows; this reduces the sensitivity to energy inputs and maintains habitat for cold-water species in downstream rivers (Moore, 2006). There has been limited glaciological research in the CCRB, but modelling efforts in the Mica sub-basin indicate that meltwater from glacier ice contributes up to 25-35% of streamflow in August and September (Jost, Moore, Menounos, & Wheate, 2012). This represents a vital freshwater resource to the Columbia River system, supporting municipalities, industry, hydroelectricity generation, irrigation, and ecosystems.…”

“…Rango, Martinec, and Roberts (2008) examine glacier contributions to runoff in the Illecillewaet River basin, but with limited observational constraints and with a simplified treatment of glacier mass balance and melt processes. Jost et al (2012) and Bürger, Schulla, and Werner (2011) apply hydrological models to nearby basins of the CCRB and provide preliminary assessments of the importance and impact of glacier runoff, but these models treat the glaciers simply and also lack direct observations to constrain mass balance gradients and high-elevation meteorological conditions in the region.…”

Attribution of streamflow trends in snow and glacier melt‐dominated catchments of the Tarim River, Central Asia

“…An analysis of these effects for glaciers in Switzerland showed that the negative effect caused by glacier surface lowering compensated on average about 50% of the positive effect due to glacier area change . While changes in glacier geometry have been taken into account in hydrological modeling for climate impact analyses [e.g., Stahl et al, 2008;Huss et al, 2010;Nolin et al, 2010;Farinotti et al, 2012;Jost et al, 2012], to our knowledge they have so far not been considered for the attribution of observed discharge trends.…”

“…It is therefore necessary to include glacier mass balance estimates in the model calibration procedure [e.g., Schaefli et al, 2005;Stahl et al, 2008;Konz and Seibert, 2010;Mayr et al, 2013]. As mass balance data derived by the glaciological method are only available for few individual glaciers, geodetic glacier mass balances may be applied as an alternative [Jost et al, 2012].…”