1. State Key Laboratory of Cryosphere Sciences, Northwest Institute of Eco-Environment and Resources; Chinese Academy of Sciences; Lanzhou 730000 China
2. School of Geography and Tourism; Shaanxi Normal University; Xi'an 710119 China
3. Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment; Chinese Academy of Sciences; Chengdu 610041 China
4. College of Earth Environmental Sciences; Lanzhou University; Lanzhou 730000 China