1. a Center for Agricultural Water Research in China, China Agricultural University, Beijing 100083 and Key Lab for Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest Sci-Tech University of Agriculture and Forestry, Yangling, Shaanxi 712100, China
2. b Key Lab for Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest Sci-Tech University of Agriculture and Forestry, Yangling, Shaanxi 712100, China
3. c Key Lab for Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest Sci-Tech University of Agriculture and Forestry, Yangling, Shaanxi 712100, China
4. d Bureau of Water Resources Management, Wuwei, Gansu 733000, China
5. e Bureau of Water Resources Management, Wuwei, Gansu 733000, China