1. Key Lab. of Water Cycle and Related Surface Processes; Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences; Beijing 100101 China
2. Graduate Univ., Chinese Academy of Sciences; Beijing 100039 China
3. State Key Lab. of Soil Erosion and Dryland Farming on the Loess Plateau; Institute of Soil and Water Conservation, Northwest A & F Univ
4. Institute of Soil And Water Conservation, Chinese Academy of Sciences, Ministry of Water Resource; Yangling 712100 Shaanxi China
5. Lab. of Soil Physics, Center for Nuclear Energy in Agriculture; Univ. of São Paulo; CEP 13418-900, CP 96 Piracicaba SP Brazil