1. Ph.D. Student, College of Hydrology and Water Resources, Hohai Univ., Nanjing 210098, China.
2. Professor, College of Hydraulic and Civil Engineering, Xinjiang Agricultural Univ., Urumqi 830052, China.
3. Professor, College of Hydrology and Water Resources, Hohai Univ., Nanjing 210098, China (corresponding author).