Pipeline Optimization for an Economical Microsprinkler Irrigation System Based on a Hybrid Genetic Algorithm

The pipeline combination scheme is optimized to reduce the cost of irrigation units in an economical microsprinkler system. With the standard number of segments of branch and capillary pipes as the decision variables, the lowest pipe cost per unit irrigation area as the objective function, the maximum pressure difference allowed in the system, the minimum number of pipes in the network, and the shape of the irrigation area as constraints, a hybrid genetic algorithm is used to calculate the minimum cost per unit area of the pipe and the corresponding optimal combination of pipelines. The results show that when the irrigation area is a rectangular plot of 30 m × 22 m, the lowest cost of pipeline per unit area, 5192.7 RMB/hm2, is achieved when the capillary pipes are laid bidirectionally along the length of the plot. The cost of bidirectional laying of capillary pipes is less than that of unidirectional laying, and the cost of capillary pipe laid along the length direction of the plot saves 2.3% compared with that of capillary pipe laid along the width direction of the plot. The most extended length of capillary pipe on one side is 103.65 m. Compared with the cost obtained by farmers based on experience, the pipeline cost per hectare was 1.04%∼13.6% lower. It is recommended that farmers lay capillary pipes bidirectionally along the length of the plot and choose branch pipes with smaller diameters to help reduce the cost of the pipe unit area of the irrigation system.