Multi-objective Optimization Model For Main Crops Planting Structure Based On Genetic Algorithm

Manas county is located in the hinterland of Xinjiang province,the contradiction between water supply and demand under the most strictest water resources management system is apparent.It is an urgent problem to increase agricultural output value to promote local sustainable agricultural development.Manas county has been very advanced in the water-saving technology,irrigation level in manas county is in a leading position in Xinjiang province.The space of developing water-saving agriculture will very limited if relying on the innovation of irrigation technology only,so it is very necessary to explore the agriculture’s direction and release the contradiction between water supply and demand from the point of view of planting structure.This study aims at the unreasonable planting structure in Manas county,then building a planting structure optimization model and it’s optimization evaluation system on the basis of analysis of planting structure of agricultural water.The model of planting structure is addresses to provide theoretical basis for exploring the solution of efficient utilization of agricultural water resources in arid inland area.Main results of this paper are as follows:(1)Taking agricultural output value maximization and water consumption for agricultural irrigation minimization as goals,building a multi-objective optimization model for planting structure based on genetic algorithm.By using genetic algorithm to solve the model,using the gamultiobj function in MATLAB software,which is based on a multiobjective optimization algorithm.The population size is 200,the maximum evolutionary generations are 1100,the crossover rate is 0.80,the mutation rate is 0.01 and multiobjective parameter is 0.35 when using the genetic algorithm.(2)Planting structure adjustment results in Manas county show that the total net output value of planting industry of 2015,2020 and 2030 level year can be increased by 4.27%,32.29%and 41.67%,and it can reduce irrigation water consumption by 0.1562 million cubic meters,18.6135 million cubic meters and 36.3578 million cubic meters.The total net water value of per cubic meter is 4.47 Yuan,5.95 Yuan and 6.69 Yuan,which can be increased by 4.44%,39.02%and 56.31%.The results show that it can relieve the contradiction between supply and demand of agricultural water on the basis of economic,social and water saving benefits.Compared with the planting structure of 2015.the planting proportion of high water consumptive crops such as wheat and cotton can be decreased by 0.48%and 0.3 1%,the planting proportion of low water consumptive crops such as corn can be increased by 0.57%,the planting proportion of special economic crops such as grape and tomato can be increased by 0.61%and 0.15%,the planting proportion of traditional economic crops such as melons and vegetables can be decreased by 0.04%and 0.01%.(3)Designing the comprehensive evaluation index system by using the method of AHP that modified.The evaluation results show that the most effective planting structure optimization in different level years in Manas county is 2030 level year,followed by 2020 level year,2015 year after the optimization and 2015 before the optimization.Judging from this,the planting structure optimization can improve economic benefits,social benefits and the utilization rate of water resources.As a result,the planting structure optimization is reasonable and feasible.