Optimization of paddy rice irrigation schedule considering effective utilization of rainfall
CHEN Mengting1,2, YANG Lin1*, WU Guangxing1, WU Zhengguang1, MAO Zhi2, CUI Yuanlai2, LUO Yufeng2
1. CAMCE WHU Design & Research Co., Ltd., Wuhan, Hubei 430200, China; 2. State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan, Hubei 430072, China
Abstract：In order to use rainfall and develop water-saving irrigation better, a new method for optimization of paddy rice irrigation schedule in south China was proposed taking a case study over the Zhanghe irrigation area in Hubei province. According to the long series of historical meteorological data, the conventional flooded schedule was optimized by growth stages through changing the criterion of field water depth in each growth stage to search the optimal water depth combination which makes the best use of rainfall and reduce irrigation times, and the causes and effects of water saving were analyzed. The results indicated that after optimization, the lower limit of water depth was reduced by 10 mm and the maximum allowable water depth after rainfall was increased by 10 mm, while the upper limit of water depth was 50, 50, 55, 40 and 25 mm respectively from the early tillering stage to the milk-ripe stage. Compared with the conventional flooded irrigation schedule, the optimization irrigation schedule can increase rainfall utilization rate by 3.78% on average with the largest increase at the early tillering stage(6.41%)and decrease irrigation times by 4.60 times on average with the largest decrease at the mike-ripe stage(2.44 times)and decrease irrigation water by 5.14% on average with the largest decrease at the jointing-booting stage(7.23%).
