1. Institute of Soil and Water Conservation, State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau; Northwest A&F University; Yangling Shaanxi 712100 China
2. Institute of Water Saving Agriculture in Arid Areas of China; Northwest A&F University; Yangling Shaanxi 712100 China
3. Institute of Soil and Water Conservation; Chinese Academy of Sciences and Ministry of Water Resources; Shaanxi 712100 China
4. College of Natural Resources and Environment; Northwest A&F University; Yangling Shaanxi 712100 China