1. Faculty of Geography, Yunnan Normal University, No. 768 Juxian Road, Kunming 650500, China
2. Department of Land Resource Management, School of Public Administration, China University of Geosciences, Wuhan 430074, China
3. Center for Turkmenistan Studies, China University of Geosciences, Wuhan 430074, China
4. State Key Laboratory of Remote Sensing Science, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, China
5. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, China