基于SWAT模型的昌江流域土地利用变化对水环境的影响研究

土地利用快速变化对水环境带来较大影响,定量分析土地利用与水环境污染的关系是土地利用结构调整的重要依据。利用3S技术,通过SWAT模型对1983年与2012年昌江流域的水量和水质模拟,分析了土地利用时空变化,结合氨氮、总磷模拟数据,定量分析了土地利用变化下该流域的水环境污染负荷。研究结果表明:该区域林地、草地、水域、城镇及建设用地呈增加趋势,耕地则呈减小趋势。林地占比最大,为70%左右,其次为水田。水田为水环境非点源负荷贡献的第一大来源,且其占流域略多于20%的面积,贡献了该区域总磷总量的53.48%~57.01%和氨氮总量的51.86%~56.57%;农业耕作以25%的地类面积,贡献了60%~65%的非点源污染负荷;旱地的单位面积贡献污染负荷高于林地及城镇及建设用地,表明农业非点源污染是该区域水环境非点源污染的主要来源。

WATER ENVIRONMENT IMPACT UNDER DIFFERENT LAND USE IN CHANGJIANG RIVER BASIN BASED ON SWAT MODER

With the intensification of the harsh climate and increase of human activities,land use is changing rapidly in the basin scale,and environmental effects caused by land use change is one of the key issues of global change processes.It brought a greater impact on the water environment,and quantitative analysis of the relationship between water pollution and land use is an important basis for land use restructuring.Based data analysis using GIS,with remote sensing image data as an important data source of the SWAT model,through the SWAT modelling water quantity of ChangJiang basin and simulating water quality in 1983 and 2012,the land use spacetime change was analyzed,and the relation with the land use of tributary Changjiang basin in Poyang lake basin and the water pollution of the environment was explored.The most sensitive parameters in this SWAT model were crop management parameters,chemical fertilizer parameters and soil parameters.Nitrogen model output was positively related to application rates of fertilizer and soil nitrogen content.In calibration period and validation periods,ammonia nitrogen and total phosphorus was consistent with the measured and simulated values.In calibration period and validation period,ammonia nitrogen relative error evaluation index were 19.67 and 23.89,the correlation coefficient R2 of ammonia nitrogen were 0.817 5 and 0.763 2; while total phosphorus evaluation index relative error were 21.95 and 31.33 respectively,the correlation coefficient R2 of total phosphorus were 0.838 3 and 0.756 7.The precision of the model met the requirements of the month load simulation.The area of woodland,grassland,water,urban construction land showed an increasing trend,but farmland showed a decreasing trend.Woodland showed the largest proportion of 70％,followed by paddy fields.Paddy contribution to nonpoint source loads of water environment was the greatest,and the basin was slightly more than 20％ of the area.The contribution of the total phosphorus to the total amount was 53.48％-57.01％,and 51.86％ 51.86％ for the total ammonia nitrogen.Dry land per unit area contribution was higher than the forest and urban construction land.It suggests that agricultural non-point source pollution is the main source of agricultural nonpoint source pollution of water environment.Farming with 25 ％ of the land area,contributed 60％-65 ％ of the nonpoint source pollution load.Therefore,reducing the application of chemical fertilizers and improving the utilization of chemical fertilizers are the most effective way to reduce non-point sources of water environment pollution; while the contribution of forest land for non-point source was the lowest,therefore,converting from farmland to forest will reduce water environmental non-point source pollution.The research results can help to water environment management decisions.