1. Associate Professor, School of Hydraulic Engineering, Changsha Univ. of Science and Technology, Changsha, Hunan 410114, P.R. China.
2. Graduate Student, Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha, Hunan 410114, P.R. China.
3. Lecturer, Ocean College, Zhejiang Univ., Hangzhou, Zhejiang 310058, P.R. China (corresponding author).