1. Heihe Remote Sensing Experimental Research Station, Key Laboratory of Remote Sensing of Gansu Province, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
2. School of Geography, Liaoning Normal University, Dalian 116029, China
3. Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
4. Qinghai Research and Design Institute of Environmental Science, Xining 810008, China
5. College of Eco-Environmental Engineering, Qinghai University, Xining 810016, China