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Titolo:
Sedimentary effects on the expansion of a Himalayan supraglacial lake
Autore:
Chikita, K; Jha, J; Yamada, T;
Indirizzi:
Hokkaido Univ, Grad Sch Sci, Div Earth & Planetary Sci, Sapporo, Hokkaido 0600810, Japan Hokkaido Univ Sapporo Hokkaido Japan 0600810 oro, Hokkaido 0600810, Japan Minist Sci & Technol, Dept Hydrol & Meteorol, Babar Mahar, Katmandu, NepalMinist Sci & Technol Babar Mahar Katmandu Nepal r Mahar, Katmandu, Nepal Hokkaido Univ, Inst Low Temp Sci, Sapporo, Hokkaido 0600819, Japan Hokkaido Univ Sapporo Hokkaido Japan 0600819 oro, Hokkaido 0600819, Japan
Titolo Testata:
GLOBAL AND PLANETARY CHANGE
fascicolo: 1-4, volume: 28, anno: 2001,
pagine: 23 - 34
SICI:
0921-8181(200102)28:1-4<23:SEOTEO>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
TURBIDITY CURRENTS; NEPAL HIMALAYA; TSHO-ROLPA;
Keywords:
supraglacial lake; sediment fallout; sediment-laden underflow; sedimentation rate; grain size statistics;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
20
Recensione:
Indirizzi per estratti:
Indirizzo: Chikita, K Hokkaido Univ, Grad Sch Sci, Div Earth & Planetary Sci, Sapporo, Hokkaido 0600810, Japan Hokkaido Univ Sapporo Hokkaido Japan 0600810 do 0600810, Japan
Citazione:
K. Chikita et al., "Sedimentary effects on the expansion of a Himalayan supraglacial lake", GLOBAL PLAN, 28(1-4), 2001, pp. 23-34

Abstract

Supraglacial Tsho Rolpa Lake in the Nepal Himalaya has been increasing rapidly in size since the 1950s, corresponding to the mountain-glacier shrinkage after the Little Ice Age. The lake basin expansion results from the subsidence by dead-ice melt below the bottom of the lake, and the retreat of the glacier terminus. Field observations of Tsho Rolpa in 1996 revealed that the retreat of glacier terminus is connected to a wind-induced vertical circulation of surface water heated by solar radiation. In order to clarify the mechanism of the lake expansion associated with sedimentary processes, wemeasured bottom sedimentation rate with some sediment traps, and vertical suspended sediment concentration (SSC) and water temperature, and analyzed the grain size of suspended and trapped sediments. The sediments, mostly composed of clay-sized grains, are dominantly supplied by glacier-melt water inflow at the glacier terminus, Sedimentary processes of such fine sedimentcomprise: (1) suspended-sediment fallout from intrusion of horizontal currents, (2) sediment sorting by sediment-laden underflows; and (3) the debrissupply from the ice collapse at the glacier terminus. The (I) and (2) processes produce the density stratification of the lake, accompanied by a pycnocline at a depth of about 27 m. The existence of the pycnocline builds up the vertical water circulation in the surface layer to enhance the glacier-melt at the terminus. With respect to the subsidence of the lake bottom, nearly molecular thermal diffusion is probably dominant near the bottom of the deepest point, which results from the kinetic-energy dissipation of sediment-laden underflows. The stable existence of the bottom turbid water throughout the year could cause continuous dead-ice melt below the lake bottom. (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/09/20 alle ore 01:07:50