基于NSGA-Ⅱ的灌区水资源优化配置模型及应用

Water Resource Allocation for Irrigation Optimized Using the NSGA-ⅡModel:Theory and Application

【目的】解决灌区水资源短缺、农业用水效率不高的问题,为灌区水资源管理提供科学依据。【方法】基于大系统分解协调原理构建了包含灌区作物种植结构和作物灌溉制度的层次优化模型,并剖析第1层模型中灌水时间对灌溉制度优化的影响,以及第2层模型中生态效益对作物种植结构优化的影响。以宝鸡峡五泉灌区为研究对象,构建了2层协调优化模型,并利用非支配排序遗传算法,实现了灌区水资源的优化配置。【结果】①以灌水量和灌水时间为优化对象的优化设计方案,可以提高灌区整体经济效益。第2层模型不考虑生态效益时,灌水量与灌水时间同时优化时的经济效益较只优化灌水量时增加1.87%,而第2层模型考虑生态效益时,对应的增长率为1.32%。②在作物种植结构的优化模型层引入生态效益优化目标,虽然经济效益有所降低,但优化后的经济效益依然显著高于现状种植结构下的经济效益,方案1、方案2、方案3和方案4与现状情况下的经济效益相比,增长率分别为15.72%、15.27%、15.99%和15.07%。③考虑生态效益后,优化后的生态耦合度值与现状相比也有所提升,提高23.5%。【结论】采用第1层模型优化灌溉水量和灌水时间,且第2层模型考虑经济效益和生态效益的方案,可实现水资源最优配置。

【Objective】Water scarcity hinders agricultural production in many countries,and how to rationally allocate water resources for irrigation is hence important to make the most of the limited water resources in areas such as northern and northwest China where water is scarce.The purpose of this paper is to present an optimization method to rationalize regional water allocation for irrigation.【Method】We constructed a two-stage optimization model considering plant structure in one layer and plant irrigation in another layer.The principle of system decomposition and coordination were used to allocate the water resources to different irrigation areas.The first layer of the optimization model was to analyze the effect of irrigation time and irrigation scheduling on economic return,and the second layer was to calculate its consequence for the effect of ecological benefits.We applied the model to the Wuquan irrigation district at Baojixia in Shannxi province,with the optimization solved by the non-dominant genetic algorithm.【Result】①The optimization model considering irrigation amount and irrigation time can improve the economic benefits.②In the plant structure layer,adding the ecological benefits to the optimization objective reduced economic benefits but the overall optimized benefits were still significantly higher than the economic benefits obtained without considering the ecological benefits.③Considering the improved ecological benefits,the optimized results considering the ecological benefits improved 23.5%of the overall return compared with those obtained without considering them.【Conclusion】Optimization of water resource allocation for irrigation should consider both economic and ecological benefits in the second layer,and the irrigation amount and irrigation time in the first layer.The optimization model we proposed in this paper can help make most of water resources for irrigation in regions where water is scarce such as northwestern China.