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| Titel |
Quantifying the contribution of glacier runoff to streamflow in the upper Columbia River Basin, Canada |
| VerfasserIn |
G. Jost, R. D. Moore, B. Menounos, R. Wheate |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 16, no. 3 ; Nr. 16, no. 3 (2012-03-19), S.849-860 |
| Datensatznummer |
250013215
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| Publikation (Nr.) |
 copernicus.org/hess-16-849-2012.pdf |
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| Zusammenfassung |
| 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
depletion. Although the sensitivity of streamflow to historic glacier area
changes is small and within parameter uncertainties, our results suggest
that glacier area changes have to be accounted for in future projections of
late summer streamflow. Our approach provides an effective and widely
applicable method to calibrate hydrologic models in glacier fed catchments,
as well as to quantify the magnitude and timing of glacier melt
contributions to streamflow. |
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