Research On The Current Situation Of Water Pollution In Mayang Town Of Tianmen City And Its Comprehensive Land Improvement Model

Water is the source of life for all things.As one of the basic elements of ecological environment,water environment is an important place of social and economic activities,which is closely related to the survival and development of human beings,and is also the most seriously disturbed and damaged area by human beings.As the most direct manifestation of human transformation of nature,land-use mode is closely related to the quality of water environment By discussing the impact of land-use on water quality to build a regional comprehensive land improvement mode and use it as a means to guide the optimization of regional land-use structure has become the current research hotspot.This dissertation takes Mayang Town,which is located in the core area of Jianghan Plain,as the research object.Based on the collection and detection of water samples in the study area,the water environment quality is evaluated by using the water quality index method and the spatial characteristics of water pollution in the later stage of traditional land improvement area are analyzed by spatial interpolation,and buffer zones of different spatial scales are established with water sample points as the center.The response relationship between land use and water quality in the study area is discussed by using redundancy analysis method.On this basis,the comprehensive land improvement mode of Mayang town is constructed and the land use structure of the study area is optimized by using multi-objective linear programming model to maximize the ecological benefit value.The main conclusions are as follows:(1)Among the eight water environmental indicators in the study area,the average concentrations of TN,ORP and SPC are 4.684 mg/L,220.482 mg/L and 457.955us/cm respectively,which are seriously over standard;the average values of pH,TP and NO3--N are 8.30,0.355mg/L and 0.11 mg/L,which are relatively normal;the average concentrations of DO and NH3-N are 8.91mg/L and 1.55mg/L respectively,the indicator concentration is better,but there is eutrophication in the whole water body.(2)The degree of water pollution in the study area shows the spatial distribution characteristics of decreasing from the northwest--southeast line to the northeast--southwest.The high value area appears in the northeast corner,the eastern edge area and the southwest corner of the study area and the low value area appears in the most of the southeast and northwest corner.The disordered discharge and lack of effective treatment of foreign sewage,production sewage and domestic sewage are the main reasons for the predicament of water pollution in the study area,and the small-scale ecological land treatment has a significant effect on water pollution treatment.(3)With the increase of spatial scale,the land use types in the buffer zone of each water sample point gradually show diversity and the proportion gradually tends to balance from extremely great disparity.In each spatial scale,the upland field occupies the dominant position,followed by paddy field,water area and construction land.The proportion of forest land is the smallest and there is no distribution in some water sample buffer areas.The proportion of land use type area in the spatial scale of each water sample point is consistent with the proportion of the overall land use structure of the study area,which shows that the data of buffer zone is scientific and reasonable.(4)The correlation between water quality indicators is always very significant.The correlation and the magnitude of correlation intensity between different land use types and different water quality indicators change with the change of scale.Water area and ditch water quality have strong positive correlation in each observation scale,upland field and ditch water quality have strong negative correlation over 200m,forest land and ditch water quality have strong negative correlation in most observation scales,paddy field and ditch water quality have strong correlation in a large scale and construction land and ditch water quality have no obvious correlation.(5)Taking the maximization of ecological benefit value as the objective function,a multi-objective planning model is constructed to optimize the land use structure of Mayang town.In 2017,the total value of the ecological benefit of Mayang town was 63753041.86 yuan.After the optimization of the land use structure,it will be increased to 65425629.26 yuan by 2020 and the total value of the ecological benefit will be increased by 1672587.40 yuan.It shows that the optimization of land use structure by comprehensive land improvement is beneficial to improvement and restoration of the ecological environment.(6)Based on the actual situation of the research area,this dissertation puts forward the comprehensive land improvement mode of Mayang Town,which takes the ICU optimization design method as the core.Taking the "water" element treatment as the breakthrough point,the dissertation optimizes the land spatial layout of the research area,strengthens the adjustment of land ownership,promotes the modern industry in the countryside,widely applies the ecological methods and processes,breaks through the water pollution dilemma and provides a reference for water pollution control in Jianghan Plain.