Why is Qilian Mountain called "Alpine Reservoir"?

Qilian Mountain is a group of parallel folded fault-block mountain ranges on the south side of Hexi Corridor, with a length of 900- 1000 km and an altitude of over 3000 meters, among which there are 26 peaks over 5000 meters. Qilian Mountain is an ancient Xiongnu language, which means "Tianshan Mountain", that is, the mountain peaks soar into the sky. There are 3066 glaciers in the mountain with a total area of 2062.72 square kilometers, which are typical plateau glaciers. Glacier reserves reach 1 145 billion cubic meters, and its meltwater is the water source foundation of Hexi Corridor Oasis, so it is called "alpine reservoir".