关键词: 冰川变化, 遥感解译, 乌鲁木齐河流域, 气候变化, 小冰期

Abstract: Change in the extent of glaciers are among the best natural indicators of climatic change. Current glacier fluctuations have important implications for water supply, fisheries, aquatic ecosystems, and seal-level change. However, most studies of glacier variations in western China focus on the recent 50 years, the researches involve in glacier changes since the Little Ice Age is relatively less. The Urumqi River Watershed is a typical northwest inland basin, the glaciers in this region provide important resources for local economic development and drinking water for man use. So this river basin has become one of the most important continental river research base. Thus, a case study of glacier changes in the Urumqi Basin since the Little Ice Age is representative. Based on 1:50000 topographic maps in 1964, Landsat TM remote sensing image in 1989, Spot5 images in 2005, Landsat8 image in 2014 and digital elevation model (ASTER-DEM), the study regions of glaciers were extracted by using remote sensing and the changes of glaciers in the study area were analyzed under the support of the geographic information systems technology. According to spot5 images, the glacier boundary of the Little Ice Age were extracted. At the same time, referring to Google earth, topographic map and TM images to improve the accuracy of the boundary. The glacier boundary in 1964 were based on ArcGIS10 to digitization the topographic map. The glacier boundaries in 1989, 2005 and 2014 were extracted through visual interpretation, meanwhile, images overlay DEM to visual amend. This method is the highest accuracy to achieve the boundary of glaciers at present. The result indicate that the analysis of 73 glaciers in which moraine ridge can be easily observed during the Little Ice Age Maximum shows that the total area of glaciers decreased 37.22 km², at a rate of 64.84% in the period LIA-2014, and the total length of glaciers decreased 52878.67 m at a rate of 49.83%. Since 1959, the observed mass balance of Urumqi No.1 glacier continued losses. In the altitude of 3300-4000 m, the area of glaciers decreased significantly, the glaciers at an altitude of 3400-3600 had disappeared. The orientation analysis of glaciers shows that the glaciers in north direction were more than those in other directions. The area of glaciers decreased in all the directions and deceased relatively small in southwest direction, the reduction rate of glaciers to the east slope of Urumqi River Basin was largest. Analysis showed that the reasons of the large change rate of glaciers is caused by the large proportion of small glaciers, whose glaciers smaller than 1 km² account for 75.3% in the investigated glaciers. And those glaciers have the highest degree of response to climate change. The analysis of the meteorological data from Daxigou weather stations from 1959 to 2013 shows that the main reason of the glacier shrinkage in Urumqi River watershed is that the glacier mass supply of increased precipitation could not fill the gap of the huge glacier mass loss caused by rising temperature.

Key words: glacier changes, RS interpretation, Urumqi RiverWatershed, climate change, Little Ice Age