Optimization Of Watershed Planting Structure In Xingyun Lake Basin Based On Water Pollution Prevention And Control

Lakes,as the important resource of sustainable development,can promote the rapid,steady and sustained development of the local economy.However,the phenomenon of eutrophication in lakes is more serious increasingly,affecting the exertion of lake's own value.How to prevent and control the degree of water environmental pollution without reducing the living standards of local residents has become one of the research hotspots of the river basin.In the past ten years,the farmers have been driven by economic interests in the Xingyun lake basin.The planting area of economic crops has been greatly expanded,occupying the area of the grain crops,and the planting structure and distribution of the Xingyun lake basin have changed a lot.As a result of high cropping,high fertilization,and high loss,the loss amount of chemical fertilizers in the crop farming in the basin has increased year by year.Nitrogen and phosphorus contaminants contained in chemical fertilizers have entered rivers and lakes along with surface runoff and underground leaching.The rivers into the lakes will eventually lead to a deeper eutrophication of the water in Xingyun Lake.So optimizing the planting structure of the Xingyun lake basin to reduce the loss amount of chemical fertilizers can prevent and control water pollution in Xingyun Lake significantly.Therefore,based on the analysis of the temporal and spatial variation characteristics of non-point source pollution in Xingyun lake basin during the past 2005-2015 years,this paper use multiple linear regression models to get the driving force of non-point source pollution.And then the optimization of the planting structure is proposed by constructing the linear programming model.Finally,the suggestion of the spatial distribution of the planting industry in the Xingyun lake basin is put forward.The results provide the basis for the control of the water pollution of Xingyun Lake and the sustainable development of the social and economic development in the Xingyun lake basin.Results indicate that:?1?The amount of internal fertilizer loss in the Xingyun lake basin increased during 2005-2015.Jiangcheng town had the biggest loss amount while Jiuxi town had the smallest.There were seven towns in the study area,of which the loss amount above100t was Dajie town,Jiangcheng town and Qianwei town.There were five kinds of pollutants?total nitrogen,total phosphorus,ammonium nitrogen,nitrate nitrogen and total soluble phosphorus?.Among that,the total nitrogen and total phosphorus loss amounts were more than 90%of total chemical loss.The total nitrogen,total phosphorus and ammonium nitrogen losses increased year by year,and their spatial distribution areas were mainly concentrated in the western and southwestern regions of the Xingyun Lake and expanded to the northwest and south regions gradually.The loss of nitrate nitrogen was decreasing year by year,and its spatial distribution area was mainly concentrated in the northern region.The total loss of total soluble total phosphorus had a stable trend in ten years,and its spatial distribution area was mainly concentrated in the Dajie town and Jiangcheng town.?2?There were some indexes,such as the proportion of the agricultural population,the proportion of cultivated land,the planting area of the economic crops and fruit trees,the proportion of the economic crops and grain crops,and the output value of the primary industry,showing a positive correlation with the loss amount of chemical fertilizer.While other indexes including the sown area of grain crops,non-agricultural income per capita,and environmental protection investment index were all negatively related with the amount of chemical fertilizer.And the correlation between planting structure and the loss amount of chemical fertilizer was highest.Farmers,at the age of 40-55,were the main labor force in the Xingyun lake basin and had a low level of education.Their per capita non-agricultural incomes were 1500-2500yuan per year.As for the planting structure,the ratio of sowing area between the economic crops and the grain crops was distributed in 3-4,and the replanting index of the crops was distributed in 3-4.As for the economic cost,the moderate increase of the price of chemical fertilizer will not affect the application amount of fertilizer application.It will affect application amount when the price rising more than 20-30%.And only when the price of cash crops rises more than 5 yuan,farmers may consider adding the planting area of cash crops.There is no influence of government subsidies on farmers,and the environmental awareness of farmers was general level with 2-3 points that total points was 4 points.?3?In 2005-2015,the overall planting area was increasing in the basin.Among them,the Jiangcheng town had the largest planting area,while the Jiuxi town had the smallest.As for the planting structure,the economic crop had the largest planting area,while the fruit tree had the smallest.The planting area of rice and dry crops decreased year by year,while the planting area of economic crops increased,and the planting area of fruit trees increased first and stabilized finally.In the point of slope degree,the planting area of gentle slope was more than steep slope.?4?The linear programming model is constructed to optimize the planting structure of the Xingyun lake basin in 2020.The results showed that:The planting area of rice,dry corps,economic crops and fruit tree will be 3564.195 ha,2640.144 ha,7927.971 ha,and 12.46 ha in 2020.The loss amount of chemical fertilizer after the optimization of Xingyun lake basin will be 712.58t,of which TN decreased obviously followed with TP and NH₄-N,while the loss of NO₃-N and DTP increased a little.The spatial distribution of the planting structure in 2020 was based on structure of 2015.Therefore the economic crops in the restricted areas in Jiangcheng town,Luju town and Dajie town should be changed to plant rice,and the economic crops in the restricted areas in Qianwei town should be changed to plant dry crops,and the economic crops,unused land and grassland beyond the restricted areas in Dajie town and Jiangcheng town should be changed to plant fruit trees.