1. School of Geoscience and Technology, Southwest Petroleum University, Chengdu, China
2. Sichuan Water Resources and Hydroelectric Investigation & Design Institute, Chengdu, China
3. School of Civil Engineering and Geomatics, Southwest Petroleum University, Chengdu, China
4. State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China