The Recent Change of Water Level in the Bosten Lake and Analysis of Its Causes
WANG Run 1, 2, Ernst Giese 2, GAO Qian-zhao 3 (1.Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing Jiangsu 210008, China; 2.Center for International Development and Environmental Research, University of Giessen, Giessen D-35390, Germany; 3.Cold and Arid =Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou Gansu 730000, China)=
Since 1987 the water level of Bosten Lake in Uygur Autonomous Region of Xinjiang has risen continuously, and the lake area reached the greatest since the 1950 s. It can be supposed that this change is related directly to the increase of runoff in the Kaidu River, which supplies about 85% of water in the whole catchments. Naturally, the runoff of the Kaidou River is influenced much more by the fluctuation of climate, since the river originates from glaciers and snow cover in the Tianshan Mountains. Much research work about the global change showed the evident ascending tendency of annual average air temperature in the last 20 years in Central Asia. Additionally, the local climate data also manifested a warming up. In this paper the relationship between the warming up and the increasing of runoff is analysed with the selected air temperature data in the east ranges of the Tianshan Mountains. Although the result shows that the increasing of runoff is correlative with climate change, it is not clear either glacier ablation or precipitation plays more important role in the level change in the Bosten Lake. Because of lack of precipitation data in the high altitudes of the Tianshan Mountains, the question remained is how to determine the direct cause for the change of water level. Some research methods for this question are checked and discussed in this paper. The influence of climate change on water resources in a catchment is critically examined with an example in the Glacier National Park.