Irrigation Scheduling and Water Distribution Evaluation Model Based on Water Supply Flow Rate

Abstract

An open-channel water distribution system is often the main infrastructure for agricultural irrigation, and a reasonable water distribution scheme can improve the efficiency of agricultural water use. This paper discusses different water distribution methods for lower-level channels based on different water supply flows of higher-level channels and meeting the constraints of the water distribution system. The water distribution method first meets the water demand of the lower-level channels and affords as much convenience to the on-farm management as possible. In this paper, water distribution evaluation indices are also selected to judge the advantages and disadvantages of the water distribution scheme. The optimization solution method NSGA-II was used, and the feasibility of the method was illustrated with the water distribution scheduling of a typical traditional open channel network (secondary channels and tertiary canal systems in large irrigation districts in China). The results indicate that the model effectively determines the optimal irrigation strategy, either continuous or rotational, based on the varying water supply flow rates from the higher-level channels. Furthermore, it provides a comprehensive evaluation of water distribution efficiency, highlighting the impact of these strategies on resource allocation. The irrigation scheduling and water distribution model presented in this study offers practical benefits for large-scale agricultural irrigation systems. By adapting to varying water supply flow rates from higher-level channels, the model ensures efficient water distribution while considering operational constraints. This flexibility is particularly beneficial in regions with fluctuating water availability. In irrigation districts with secondary and tertiary canal systems, the model optimizes irrigation strategies by selecting either continuous or rotational irrigation based on flow conditions. Continuous irrigation is applied when the upper channel receives high flow rates, whereas rotational irrigation is used for medium or low flow rates. Gate-controlled distribution in tertiary channels further enhances water management efficiency, reducing leakage and water abandonment. The model’s water distribution evaluation indices offer clear and intuitive assessments, helping irrigation managers identify recommended strategies. Tested on a two-level canal system, the model’s applicability to more complex systems and other distribution methods, such as upstream–downstream gradual distribution, warrants further exploration. Overall, this model provides an effective tool for improving water use efficiency and supporting sustainable agricultural practices in large irrigation districts.