Discharge Regulation Considering the Variation of Natural Parameters in Border Field

The variability of natural parameters in border fields is one of the main factors leading to poor irrigation performance. To explore the impact of natural parameter variation on border irrigation performance, a four-year field irrigation experiment was conducted in this study, and the obtained parameters were combined with the WinSRFR V4.1 model to simulate the advance–recession process under different discharge scenarios. Based on the observed and simulated data, the influence of natural parameter variation on the flow process of constant discharge irrigation was analyzed, and thus the optimal observation points for advancing and discharge regulation strategy were further established. The results indicated that in a constant discharge border irrigation system, the irrigation performance index showed a trend of first increasing and then decreasing with the increase in discharge, and the variation range of the reduced section was smaller than that of the increased section. Therefore, the risk of inefficient irrigation caused by flow fluctuations could be reduced to a certain extent by increasing the discharge. Additionally, variability in natural parameters also caused the water advance time to deviate gradually from expectations, and the deviation would be obvious when the flow advanced to the point of 40 m. The adjustment range of the optimal regulation discharge qM was greater than the corresponding optimal constant discharge qD2 under natural parameter variations. In the ideal situation of uniform natural parameters within the border, the optimal discharge regulation scheme could improve the application efficiency, irrigation uniformity, and water storage efficiency to 97.3%, 95.5%, and 96.9%, respectively. The results of this study can provide a theoretical basis for the development of automatic regulation of border irrigation systems.