| Co-Investigator(Kenkyū-buntansha) |
王 す民 中国科学院, 南京地理與湖泊研究所, 付教授
YUSA Yiki Professor, Geophysical Research Station, Kyoto University, 理学部附属地球物理学研究施設, 教授 (90025403)
TOKUNAGA Eiji Professor, Faculty of Economics, Chuo University, 経済学部, 教授 (80087147)
TANOUE Ryuichi Associate Professor, Asahikawa Technical College, 助教授 (50042081)
URAKAMI Koichi Associate Professor, Faculty of Science, Hokkaido University, 理学部, 助教授 (20000870)
SUMIN Wnag Associate Professor, Nanjing Institute of Geography and Limnology, Academia Sini
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| Research Abstract |
Qinghai Lake, situated in the far easterm part of Qinghai Plateau at latitude 37ﾟN and longitued 100ﾟE, is a closed saline lake in the interior China. Its morphometric features are: 4,484km^2 in area estimated from a satellite photo, 27m in maximum depth measured in July 1988 and 14.8m in mean depth in the consideration of the decline of a lake level, based on a bathymetric map published in 1976, the lake surface being 3,193m above mean sea level at present and the basin around the lake has an area of 25,544km^2. The basin is covered by a grass, being characterized by a semi arid condition. The annual precipitation and the mean annual air temperature are respectively 375mm and -0.6ﾟC at Gangcha, based on the record from 1958 to 1986 and the mean annual atmospheric pressure is 680mb at Gangcha. The seasonal variations in precipitation are characterized by an increase in the May-October period when accounts for 90% of the annual precipitation.
The annual amount of evaporation calculated w
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as 804mm, from the meteorological data at Gangcha, based on record for the 1958-1986 period. Then the rario (f) of evapotranspiration (E_g) over the steppe basin to evaporation (E_o) of the lake surface, namely f=E_g/E_o, is estimated to be 0.37. As for the values of f in humid regions, Nakao (1971) estimated f=0.65 in the Ishikari River, in Hokkaido, Japan, and Penman (1949) estimated f=0.75 in England. As for the values of f in an arid region, Nakao (1975) estimated f=0.15 in the Lahontan Basin, Nevada U.S.A.; and in a cold arid region Nakao et al. (1981) estimated f=0.3 at the Harding Lake Basin, Alaska, which is characterized by the presence of discontinuous permafrost. This value (f=0.37) is judged to be a proper value in the dry grass basin.
The Daotang River has a wide valley and the sediment depth deeper than 400m. This closed lake was formed by the damming of anciant Daotang Valley which had flowed into the Yellow River, as the result of the uplift by a crustal movement in the south of Mt. Sun-Moon Pass in the Wurm glacial statge. Less
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