Construction-Oriented Optimization of Pressurized Irrigation Networks to Minimize Irrigation Costs

Pressurized irrigation network systems constitute an important water-saving approach, but their relatively high costs limit their promotion. Pipe diameter optimization is the most direct way to reduce irrigation costs and can bring significant economic benefits. In recent years, material technology developments have improved networks’ impact resistance, resulting in traditional flow velocity constraints no longer applying to current network designs, and appropriately increasing the velocity has become an engineering requirement. In addition, with the update of engineering construction standards, the location of pipe diameter changes is no longer limited to pipe section connections and is allowed to change between standard pipes. Therefore, this paper removes the constraint of the upper limit of flow velocity, defines it as a factor related to the maintenance cost of the network, and establishes a pipe section optimization model. Further, this paper changes the minimum optimization unit from pipe sections to standard pipes and establishes a standard pipe optimization model. The results show that compared with traditional optimization methods, the pipe section optimization model that deletes the upper velocity limit can reduce costs by 5.1%, in which the velocity will not increase infinitely but will be stable within a reasonable range. The standard pipe optimization model can reduce irrigation costs by 12.1%. It is worth noting that the two models were optimized to balance the head loss; their energy costs did not change significantly with the reduction in pipe diameter. In addition, this paper changes the structure of the traditional algorithm and designs a structure of double selection and parallel variation, achieving a faster and more accurate solution than the classic genetic algorithm.