1. a School of Earth Science, Chengdu University of Technology, Chengdu 610059, China
2. b Auburn University, Auburn, Alabama 36849, USA
3. c Center for Geospatial Analytics, North Carolina State University, Raleigh, NC 27695, USA
4. d School of Resource and Environment Sciences, Wuhan University, Wuhan 430072, China
5. e State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, China
6. f Powerchina Northwest Engineering Corporation Limited, Xi'an 710065, China