Mahboubeh Aghajani; Maryam Navabian; Majid Vazifehdost; Mojtaba Rezaee
Abstract
In recent years, discharge of Sefidroud River, which is the main source of agricultural water in Guilan province, has been decreasing because of construction of several dams in the upstream of Sefidroud basin. The future of rice production will depend on appropriate management strategy for optimization ...
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In recent years, discharge of Sefidroud River, which is the main source of agricultural water in Guilan province, has been decreasing because of construction of several dams in the upstream of Sefidroud basin. The future of rice production will depend on appropriate management strategy for optimization of water consumption in the paddy fields. In this research, to maximize water productivity in paddy fields, two optimal models were selected for irrigation management as fixed interval irrigation in the entire growing season and variable interval irrigation in different physiological growth stages of Hashemi variety, using SWAP model and Genetic Algorithm (GA). After validation of SWAP model, the chosen values were optimized by GA. In the optimal models, irrigation water depths and rice irrigation intervals were selected as the decision variables in different crop growth stages. Periodic irrigation management with fixed interval i.e. 7.33 days during the growing season, showed the maximum efficiency of irrigation water. However, the optimal variable intervals were 6.53, 4.60, 4.31 and 7.74 days during establishment, tillering stage, maturity, and harvest respectively. Finally, for saving of water, improvement of irrigation water productivity, reduction of evapotranspiration, proper irrigation interval in Sefidroud irrigation network, and ease of measurement of inflow water volume, a fixed irrigation interval of 8 days and irrigation depth of 52, 30, 40 and 12 mm in, respectively, establishment stage, tillering, maturity, and harvest stages was recommended. The highest water productivity obtained was 1.59 kg/ m3.