RS-based Monitoring Of Glacier Change In The Beidahe River Basin In The Qilian Moutains

Glacier is the biggest freshwater resource on the earth, and it is also the biggest naturalreservoir after the ocean. About11%land area were covered by the glacier, and about80%freshwater were storaged in glacier(Ice sheet).With the climate becoming warm during the20th century, most mountain glaciers of theworld are flinching, some glaciers keep advancing or steady once turn retreating now, because ofthe climate becoming warm, and during the latest20years, this situation appeared a trend ofaccelation, and then, it caused a series of serious impact, which aroused widespread concernaround the world. Beidahe river is a typical representative of inland river in our country, it is animportant water resource in Hexi Corridor oasis, which plays an pivotal role in industry、agriculture、people’s daily life for Jiuquan and Jiayuguan. As temperatures rise in recent years,glaciers in this basin has a strong ablation, this phenomenon, which had a significant impact onthe regional ecological environment and sustainable development.There is a large number of glaciers in our country, mainly distributed in the TianshanMountains, Kunlun Mountains, Qinghai-Tibet Plateau, the Qilian Mountains and other regions.And the Qilian modern glaciers are widely distributed in the high mountains above an altitude of4500m.Traditional glacier observations based on these data sources, like field surveys、topographic maps and aerial photographs. They are time-consuming、labor-consuming and lowefficiency, the observation sites are few and scattered, which are not good enough to monitoringa wide range of glaciers’ change. However, remote sensing, especially the rapid development of3S technology and the usage of high-resolution optical sensors, which provide a reliable, fast,timely, accurate, inexpensive method for remote and difficult glaciers. Because of this, in thispaper, the object of study is glaciers of Beidahe river basin in Qilian Mountain. With ASTERhigh resolution satellite image data as a data source, explore the monitoring methods of glacierchange based on ASTER image. And combined with the existing aerial topographic maps、glacier inventory data and1956/1957/1960-2005precipitation and summer temperature data,from1956to2003, the data in the two periods were analyzed, study the changes incharacteristics and causes of the glaciers of the region over the past47years.The analysis of the glacier changes of Beidahe River Basin in Qilian Mountains, shows that:the area of the glacier retreats from217.54km2to183.98km2during47years in1956-2003. Six glaciers were completely disappeared, the area of them is33.56km2. In other words,15.42percent of the glaciers were melted; and the glaciers accumulated retreated51.015km;meanwhile, the average of each glacier retreats137.23m and the ice reserves reduce2.97km3.However, the summer temperature of Beidahe River Basin shows an significantly increasingtrend, the value is0.21℃/10a and the precipitation increases10.18mm every ten years. Inaddition to the guiding factors of the glacier changes, the magnitude of the glacier retreat isrelated to the distribution characteristics of the region glaciers. That is to say, a large number ofsmall glaciers are more sensitive to climate change and the area changes greatly. With theglaciers melting aggravated, the glacier scale is to be small and enhance the sensitivity of theregional glacier to the increasing temperature. In addition, the retreat of glaciers affects bytopographical factors. Meanwhile, glacier type, orientation, slope, altitude and so on are allcontribute to different changes of the adjacent same scale glaciers.Compared with the Heihe River Basin, Yeniugou Watershed and Lenglongling, the rate ofglaciers changes of the study area is much smaller. However, the change rate of the study area isbigger than the western part of the Qilian Mountains and the period of the study is13years morethan the western part. Furthermore, compared with Urumqi River Basin of Xinjiang, KalamilanRiver Basin, Kaidu River Basin, Talimu River Basin, the middle part of Kunlun Mountains ofTibet Plateau, Pengqu Basin, Mushitage and Geladandong glaciers, the glaciers of QilianMountains have a greater change rate. Except for the climate factors, the change rate is related tothe proportion of the scale of the glacier area and the glacier’s properties.