1. Institute of Hydrology and Water Resources, Nanjing Hydraulic Research Institute; Nanjing China
2. Chuzhou Hydrology Lab.; Institute of Hydrology and Water Resources; Chuzhou China
3. Dep. of Ecosystem Science and Management; Pennsylvania State Univ.; University Park PA 16802
4. State Key Lab. of Loess and Quaternary Geology; Institute of Earth Environment, Chinese Academy of Sciences; Xi'an China