Why does agriculture in western Gansu depend on snowmelt from the Qilian Mountains?

Agriculture in western Gansu relies on snowmelt from the Qilian Mountains primarily because the region experiences extremely meager and unpredictable precipitation. As one moves further inland toward the west, annual rainfall is very low, ranging from only 2 to 3 inches in areas like Dunhuang and Jiuquan.1

The Qilian Mountains serve as a vital water reservoir, containing vast glaciers and ice that act as the most important source of water for agricultural, industrial, and public use in the Hexi Corridor to the north. Because the local climate is too dry to support traditional farming through rainfall alone, irrigation systems fed by these glacier-fed streams are essential for sustaining the region's food crop production.2134