Optimization of border irrigation variables based on a correction factor for irrigation quota.

The optimization of surface irrigation variables, i.e., the selection of the optimal combination of the inflow rate per unit width (q) and cutoff time (tco), is essential for obtaining high performance. The main objective of this study was to optimize irrigation variables by considering different irrigation requirements and the total loss model, which includes the irrigation water loss and crop yield loss. A correction factor for the irrigation quota (C) was introduced to achieve this objective. C considers different irrigation requirements, as it represents the ratio of the actual irrigation quota for certain irrigation to the designed irrigation quota (D). Uniform design theory was used to determine random combinations of q and C from a selected range. The q value ranged from 3 to 9 L m. s. Because the actual irrigation quota does not greatly deviate from the design irrigation quota, C should reach approximately 1.00. The selected C ranged from 0.80 to 1.38. To obtain higher crop yields, lower economic losses, and more reasonable design variables for surface irrigation, a total loss model for uneven border irrigation was established, which was defined as the objective function to optimize border irrigation design-the total loss model was combined with uniform design theory and the WinSRFR model to analyze different scenarios. The results showed that C has a clear meaning and exerts a favorable application effect on the irrigation performance evaluation indicators and can be used to design border irrigation systems. Based on the total loss model for uneven border irrigation, the optimal irrigation variables q and C for design irrigation quotas of 60, 80, and 100 mm are q = 6.22 L m. s and C = 1.17; q = 4.60 L m. s and C = 1.14; and q = 3.80 L m. s and C = 1.10, respectively. Compared with the conventional design results, q in the optimal design results based on the loss model decreased, C increased, and the total loss significantly decreased. Optimization of irrigation variables based on the border irrigation loss model could ensure favorable irrigation performance evaluation indicators, improve the water use efficiency, provide higher crop yields, and minimize the total economic losses caused by uneven irrigation.