1. The State Key Laboratory of Remote Sensing Science; School of Geography; Beijing Normal University; Beijing 100875 China
2. College of Global Change and Earth System Sciences; Beijing Normal University; Beijing 100875 China
3. Department of Geographical Sciences; University of Maryland; College Park MD 20742 USA
4. State Key Laboratory of Earth Surface Processes and Resource Ecology; Beijing Normal University; Beijing 100875 China
5. Academy of Disaster Reduction and Emergency Management; Ministry of Civil Affairs and Ministry of Education; Beijing 100875 China