Study On Optimization Of Multi-objective Planting Structure Under Water Resource Constraint

China is a large agricultural country,the development of agriculture has a significant impact on our economy,and the sustainable development of agriculture cannot be separated from water resources.In recent years,the problem of water shortage has become more and more serious,although the optimal allocation of water resources can alleviate the contradiction between supply and demand of water resources to some extent,it is difficult to meet the diversity and variability of water demand simply by the optimal allocation of water resources without considering the development requirements and water demand characteristics of agricultural planting.Therefore,it will be one of the important directions for agricultural water-saving in the future to formulate regional water-saving strategies based on the rational structure and layout of agricultural planting,considering the research of multi-objective planting structure optimization,it is of great significance to put forward the regional water resources utilization scheme to alleviate the contradiction between water resources supply and demand.In this study,the Beijing-tianjin-hebei region was taken as the research area,2016 as the basic year for optimization planning,and 2040 as the level year for optimization planning.The region was divided into 13 residential areas,the planting area of grain,vegetable and fruit was selected as the decision variable,the multi-objective optimization model of agricultural planting structure was established with the maximum economic benefit,minimum agricultural water consumption and maximum ecological benefit as the objective function,and the constraint conditions of planting area,total water consumption and regional crop yield requirements,the chaos particle swarm optimization(pso)is applied to solve the model.The main results of this study are as follows:(1)On the premise of not changing the planting scale in the Beijing-tianjin-hebei region,the improvement scheme of planting structure was put forward by optimizing the planting structure.Among them,after the optimization,the sown area of grain crops was reduced from 6.6767 million hectares to 4.428 million hectares,and the planting proportion was reduced by 25%.The vegetable area increased from 1.33 million hectares to 1.719 million hectares,with a 5%increase in the planting ratio,and the fruit area increased from 1.176 million hectares to 3.126 million hectares,with a 21%increase in the planting ratio.(2)After the application of the model to optimize the planting structure,the economic benefit of the Beijing-tianjin-hebei region increased by 99.226 billion yuan,and the ecological benefit increased by 1.728 billion yuan.After optimization(2040),the total water use of the three crops is 13.4 billion m3,which reduces by 672 million m3.Water use for food crops decreased by 3.5 billion m3,water use for vegetable crops increased by 789 million m3,and water use for fruit increased the most,by 2 billion m3.Regionally,the total water use of the first three crops in Beijing was 282 million m3,and the total water use after optimization was 244 million m3,reducing the total water use by 38 million m3.The total water use of the first three crops optimized in Tianjin was 673 million m3,and the total water use of the first three crops optimized in Hebei province was 13.131 billion m3,and the total water use of the first three crops optimized in Hebei province was 12.5 billion m3,and the total water use decreased by 631 million m3.(3)The optimization and adjustment of agricultural planting structure can not only meet the demand of agricultural supply-side reform,but also have a far-reaching impact on the economic output,water efficiency and ecological environment of crops.Model has been successfully applied in the Beijing-tianjin-hebei region,shows that planting structure optimization to improve the economic,ecological benefit and promote agricultural water use efficiency and benefit has great potential,and at the same time is to improve the regional economic benefits,to alleviate water shortage serious problems and improve the regulating ability of agricultural production to the ecological environment of effective measures.