Simulation and Evaluation of Technical Schemes for Water-saving Irrigation of Rice in Different Hydrological Years

In order to explore the suitable water-saving irrigation mode of rice, the cultivation experiment of rice under controlled irrigation and drainage conditions was conducted in the lysimeters from 2016 to 2017. The SWAP-WOFOST model was calibrated and validated against the data in observations of two-year agricultural field experiment. And rainfall data of 60 years were grouped according to the type of hydrological years. At the same time, the irrigation and drainage module of SWAP model was improved to meet the local irrigation and drainage needs. The validated SWAP-WOFOST model was then used to simulate soil moisture transportation and rice growth process. By comparing the difference in field water management and rice yield under different hydrological year scenarios, the effects of four water-saving irrigation modes on reducing irrigation drainage and improving yield were analyzed. The results showed that water-saving irrigation technology could reduce the amount and frequencies of irrigation and drainage, reduce the physiological water demand of rice and field leakage, maintain high yield of rice and improve water use efficiency. During the 60-year simulation period, the irrigation water productivity of controlled irrigation and drainage mode was 5.52 kg/m3, 4.65 kg/m3 and 3.83 kg/m3, respectively for the wet year, normal year and dry year, which was the highest of four modes. Crop water productivity of controlled irrigation mode was 2.45 kg/m3, 2.31 kg/m3 and 2.06 kg/m3, respectively for the wet year, normal year and dry year, which was the highest of four modes. Applying the entropy weighted TOPSIS model to evaluate and optimize the four modes of water-saving irrigation of rice, the results showed that controlled irrigation and drainage mode had a steady effect of water-saving and labor-saving on the premise of guaranteeing yield. Water-saving irrigation technology had guiding significance for irrigation and drainage practices in rice-growing areas of Southern China. © 2019, Chinese Society of Agricultural Machinery. All right reserved.