Application of Improved NSGA-II Multi-Objective Genetic Algorithm in Optimal Allocation of Water Resources in Main Tarim River Basin

As the longest inland river in China, the Tarim River is characterized by water shortage and ecological degradation in the basin, and water resources have become the most important factor restricting the sustainable economic and social development of the basin. In this paper, the optimal allocation model of water resources in the main Tarim River is constructed. The Non-dominated Sorting Genetic Algorithm II (NSGA-II) as a classical multi-objective optimization algorithm suffers from the shortcomings of high computational complexity, long time-consuming non-dominated sorting, and difficulty in diversity preservation under high-dimensional objectives. To address these problems, good point set theory is introduced to improve the distributivity of the solution set, and a linear pressure selection mechanism is utilized to improve the convergence speed of the algorithm. The model is solved by using the improved NSGA-II, and the optimal allocation scheme of water resources in the main Tarim River is proposed. The results show that the total regional water supply remains unchanged under the optimal allocation scheme, while the guaranteed rate of agricultural water supply in the ALE-XQM Irrigation District, XQM-YBZ Irrigation District, YBZ-USM Irrigation District, and CAL-DXHZ Irrigation District is increased by 4.36%, 12.11%, 37.70%, and 0.36%, respectively. The guaranteed rate of ecological water supply is increased by 0.19%, 19.05%, 19.29%, and 36.05%, respectively. And the amount of water discharged from Daxihaizi increased by 0.51 billion m3. In addition, under the three typical hydrological frequency scenarios of moderate year, medium dry year, and extreme dry year in 2030, the guaranteed rate of agricultural and ecological water supply and the amount of water discharged from Daxihaizi can better meet the design requirements. In short, the improved algorithm has obvious superiority, which can make full use of the natural incoming water of the dry river to reduce the overall water shortage and improve the water supply guarantee rate of each region. The optimal allocation scheme can provide scientific reference for the rational allocation of water resources in the Tarim River basin and has an important application value for solving the problem of water resources shortage in Northwest Arid Region.