1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin; China Institute of Water Resources and Hydropower Research; Beijing 100038 P. R. China
2. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering; Hohai University; Nanjing 210098 P. R. China
3. Centre for Agricultural Water Research in China; China Agricultural University; Beijing 100083 P. R. China
4. College of Water Science and Engineering; Yangzhou University; Jiangsu Yangzhou 225009 P. R. China