1. College of Tourism and Urban-Rural Planning, Chengdu University of Technology, Chengdu 610059, China
2. Center for Human Geography of Tibetan Plateau and Its Eastern Slope, Chengdu University of Technology, Chengdu 610059, China
3. College of Earth Science, Chengdu University of Technology, Chengdu 610059, China
4. College of Mathematics and Physics, Chengdu University of Technology, Chengdu 610059, China