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| Titel |
Modelling runoff from a Himalayan debris-covered glacier |
| VerfasserIn |
K. Fujita, A. Sakai |
| 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 ; 18, no. 7 ; Nr. 18, no. 7 (2014-07-24), S.2679-2694 |
| Datensatznummer |
250120415
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| Publikation (Nr.) |
 copernicus.org/hess-18-2679-2014.pdf |
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| Zusammenfassung |
| Although the processes by which glacial debris mantles alter the melting of
glacier ice have been well studied, the mass balance and runoff patterns of
Himalayan debris-covered glaciers and the response of these factors to
climate change are not well understood. Many previous studies have addressed
mechanisms of ice melt under debris mantles by applying multiplicative
parameters derived from field experiments, and other studies have calculated
the details of heat conduction through the debris layer. However, those
approaches cannot be applied at catchment scale because distributions of
thickness and thermal property of debris are heterogeneous and difficult to
measure. Here, we established a runoff model for a Himalayan debris-covered
glacier in which the spatial distribution of the thermal properties of the
debris mantle is estimated from remotely sensed multi-temporal data. We
applied the model to the Tsho Rolpa Glacial Lake–Trambau Glacier basin in
the Nepal Himalaya, using hydro-meteorological observations obtained for a
3.5-year period (1993–1996). We calculated long-term averages of runoff
components for the period 1980–2007 using gridded reanalysis datasets. Our
calculations suggest that excess meltwater, which implies the additional
water runoff compared with the ice-free terrain, from the debris-covered area
contributes significantly to the total runoff, mainly because of its location
at a lower elevation. Uncertainties in runoff simulation due to estimations
of the thermal properties and albedo of the debris-covered surface were
assessed to be approximately 8% of the runoff from the debris-covered
area. We evaluated the sensitivities of runoff components to changes in air
temperature and precipitation. As expected, warmer air temperatures increase
the total runoff by increasing the melting rate; however, increased
precipitation slightly reduces the total runoff, as ice melting is suppressed
by the increased snow cover and associated high albedo. The response of total
runoff to changing precipitation is complex because of the different
responses of individual components (glacier, debris, and ice-free terrain) to
precipitation. |
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