1. Shaanxi Key Laboratory of Disasters Monitoring and Mechanism Simulation; Baoji University of Arts and Sciences; Gaoxin Road 1, Baoji 721013 China
2. State Key Laboratory of Loess and Quaternary Geology; Institute of Earth Environment, Chinese Academy of Sciences; Yanxiang Road 97, Xi'an 710075 China
3. Department of geography, School of Geography and Tourism; Shaanxi Normal University; Chang'an Road 199, Xi'an 710062 China
4. Department of Hydrology and Water Resources, School of Environmental Science and Engineering; Chang'an University; Yanta Road 126, Xi'an 710054 China