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| Titel |
Potential flood volume of Himalayan glacial lakes |
| VerfasserIn |
K. Fujita, A. Sakai, S. Takenaka, T. Nuimura, A. B. Surazakov, T. Sawagaki, T. Yamanokuchi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 13, no. 7 ; Nr. 13, no. 7 (2013-07-16), S.1827-1839 |
| Datensatznummer |
250018557
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| Publikation (Nr.) |
 copernicus.org/nhess-13-1827-2013.pdf |
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| Zusammenfassung |
| Glacial lakes are potentially dangerous sources of glacial
lake outburst floods (GLOFs), and represent a serious natural hazard in
Himalayan countries. Despite the development of various indices aimed at
determining the outburst probability, an objective evaluation of the
thousands of Himalayan glacial lakes has yet to be completed. In this study
we propose a single index, based on the depression angle from the lakeshore,
which allows the lakes to be assessed using remotely sensed digital
elevation models (DEMs). We test our approach on five lakes in Nepal,
Bhutan, and Tibet using images taken by the declassified Hexagon KH-9
satellite before these lakes experienced an outburst flood. All five lakes
had a steep lakefront area (SLA), on which a depression angle was steeper
than our proposed threshold of 10° before the GLOF event, but the
SLA was no longer evident after the events. We further calculated the
potential flood volume (PFV); i.e., the maximum volume of floodwater that
could be released if the lake surface was lowered sufficiently to eradicate
the SLA. This approach guarantees repeatability to assess the possibility of
GLOF hazards because it requires no particular expertise to carry out, though
the PFV does not quantify the GLOF risk. We calculated PFVs for more than
2000 Himalayan glacial lakes using visible band images and DEMs of ASTER
data. The PFV distribution follows a power-law function. We found that 794
lakes did not have an SLA, and consequently had a PFV of zero, while we also
identified 49 lakes with PFVs of over 10 million m3, which is a
comparable volume to that of recorded major GLOFs. This PFV approach allows
us to preliminarily identify and prioritize those Himalayan glacial lakes
that require further detailed investigation on GLOF hazards and risk. |
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