干旱区生态环境知识资源中心

The Tarim river basin, a river system formed by the convergence of nine tributaries, is the most heavily glacierized watershed in arid northwest China. In the basin, there are 11665 glaciers with a total area of 19 878 km(2) and a volume of 2313 km(3). Glaciers in the basin play a significant role in the water resource system. It is estimated that they provide about 133 x 10(8) m(3) of meltwater annually, contributing 39% of the total river runoff. Under the influence of global warming, northwest China has experienced a generally warmer and drier climate since the mid-19th century. However, a so-called 'warm and wet transition' has occurred since the late 1980s, evidenced by an increase in both precipitation and stream discharge in the Xinjiang Autonomous Region and neighboring regions. This paper describes how glaciers in the Tarim river basin have responded to such warming and increased precipitation, and the impact of these glacier changes. We analyzed the variations of more than 3000 glaciers since the 1960s using topographical maps, high-resolution satellite images and aerial photographs of the river basin. Our results indicate that glaciers in the basin have been mostly in retreat in the past 40 years, and ice wastage has significantly influenced water resources in the Tarim river basin. Estimation by a degree-day meltwater model shows the positive anomaly in stream runoff of the Tailan river can be partly attributed to the increase in glacier runoff (amounting to one-third of the stream discharge), and a rough estimation using observed average ablation on the termini of 15 glaciers in China verifies that the mass loss calculated by a glacier area-volume relation is reasonable.