Permafrost

Possible Change of Runoff in the Upper Yellow River Basin under
Global Warming Scenarios
Yong-chao Lan 1 , Zhi Wei 1* , Hui-jun Jin 1 , Jun-jie Chang 2 , Xiao-hu Huo 2 , Ye-xin Xu 2
(1.Division of Hydrology and Water-soil Resource in Cold and Arid Region, Cold and Arid Regions
Environment and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, Gansu,
China; 2.Administrative Office of Hydrology and Water Resource of the Upper Reaches of the Yellow River,
Lanzhou 730000, Gansu ,China)
Abstract: Global surface’s average temperature has increased all the time since 1861, and it has
increased by 0.6±0.2 according to the 3rd science evaluation report on climatic change of
20th century by IPCC [1] . The report also showed that two periods of the most increased ranges
in 20th century are from 1910 to 1945 and from 1976 to 2000. Among the changes, climatic
change in the Qinghai-Tibet Plateau located at Northern Hemispherical high elevation area is
stupendous especially [2] .The different heated condition and the changed atmospheric circulation
inevitably cause acceleration of water cycle and redistributing of water resources in space and
time, they then affect ecological environment and the social economy development in the basin.
The recent 10 years have the highest Global average temperature since 1861 when there are
meteorological records and the lowest mean runoff in the upper Yellow Rive (at the Tangnag
Hydrologic Station) since 1956 when there are hydrology observation records), and the runoff
measured value in 2002 also is lowest since 1956. Durative decrease of runoff from the upper
Yellow River basin not only has influenced waterpower in the northwest China, but also has
influenced irrigation in the basin, and the ecological environment and national economy
development in the whole Yellow River basin. It is estimated that Global warming will continue
[3]
in 21st century, and the global average surface temperature will rise 1.5~4.5 , which will
inevitably causes the more inconsistency between supply and demand on water resources in the
Yellow River basin. Therefore, the study on the possible changes of runoff in the upper Yellow
river basin under the Global warming condition have the vital significance for constituting the
regional social and economic developmental plan and sustainable empoldering and using water
resources in the upper Yellow River basin. Therefore, the characteristics, possible causes and
variations trends on temperature, precipitation and runoff in the upper Yellow River basin above
Tangnag are analyzed according to hydrological and meteorological data for recent about 50
years at the observation stations, and the evolvement trend of runoff in the basin in the future
decades is forecasted based on the suppositional climate scenes combination in this paper. The
results indicate variation of temperature in the basin has an obvious corresponding relationship
with Global warming and it all rises differently, and it variation of precipitation has the larger
difference in every region in the basin because difference of located geography position since
the recent about 50. Runoff in the basin has been decreasing continually since the end of 1980s
because mean temperature in the basin rises and precipitation in the main areas of runoff
formation in the basin decreases. Runoff will largely decrease if precipitation decreases largely
and temperature rises continuously , whereas runoff will increase if temperature is immovable
and precipitation increases largely, well than the increase range of runoff may be more than that
of precipitation because of the supply of melt-water from snow, glacier and frozen soils in
future several decades.
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