1. Faculty of Geographical of Sciences Beijing Normal University Beijing China
2. College of Resource and Environment, State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Yangling Shaanxi China
3. Center for Information Geoscience University of Electronic Science and Technology of China Chengdu China
4. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Institute of Soil and Water Conservation, Northwest A & F University Yangling Shaanxi China