Spatio-temporal Variation Of Non-point Source Pollution Intensity In Heilongjiang Province

With the rapid development of the economic integration and the rapid development of agricultural modernization,the non-point source pollution of agriculture has become an important problem that needs to be solved in the current society.Therefore,it is of great significance to accurately and quickly grasp the pollution degree,judge and analyze the pollution intensity of non-point sources in different farming areas based on geographic information and remote sensing,which is of great significance to timely and accurately assist the government decision-making,protect the ecological environment,comprehensively revitalize the countryside and take the sustainable development road.This study is supported by multi-source data such as MODIS,modern resolution imaging spectroradiometer,land use classification map,advanced space borne thermal emission and Reflection Radiometer global digital elevation model and statistical yearbook,Firstly,the satellite remote sensing extraction model of crop planting area was constructed by analyzing the phenology and NDVI(normalized difference estimation index)time series of main crops(corn,rice,soybean and wheat)in Heilongjiang Province;Then,according to the statistical yearbook of China and Heilongjiang Province,the paper analyzes the time series of the pure application amount,application intensity and application structure of agricultural fertilizer in the province and cities,and displays the spatial distribution map in three-dimensional way,giving full play to the advantages of data Spatialization in the research of non-point source pollution;Finally,by using the method of analyzing the intensity of non-point source pollution,the paper constructs a linear regression model of the amount of fertilizer converted pure application and the area of crop planting by the method of the coupling of the spatial distribution of crops and statistical yearbook extracted by satellite remote sensing.The paper overcomes the defects of analyzing the pollution of the non-point source only by statistical yearbook,and realizes the simulation of the spatial and temporal variation trend of the intensity of the pollution of the non-point source which is coupled with the information of the planting area and fertilizer.The results show that: 1(1)In 2000-2019,the total planting area of Heilongjiang province increased significantly.The remote sensing extraction method based on MODIS Image has improved the accuracy of crop extraction,and is more suitable for local agricultural conditions,with an average precision of 81.4%,The results show that MODIS can extract the crop information effectively in large-scale farming area,and provide a feasible reference for remote sensing monitoring of regional agricultural situation and adjustment of crop planting structure.(2)In the past 40 years,the total amount of fertilizer application in the province has been increasing continuously,and from 2015,the application amount and application intensity have been showing a trend of continuous negative growth;From the city level,the fertilization intensity in Harbin,Suihua and Jiamusi is close to the international standard safety limit(225kg/ha)of chemical fertilizer application.Relevant government departments should take targeted measures to control the aggravation of non-point source pollution as soon as possible.(3)In the analysis of the intensity of non-point source pollution based on the coupling of satellite remote sensing and statistical yearbook data,the linear regression model is constructed to show that the overall agricultural non-point pollution intensity of the research area has increased to a certain extent,among which the pollution intensifies the most in northern Harbin and Sanjiang Plain.From the time sequence,the point of gravity of the non-point source pollution also has a trend of gradually moving to the northeast.At the same time,through correlation analysis,it is found that the Gross Domestic Product(GDP)of each region has a significant positive correlation with the degree of non-point source pollution,which can be used as one of the early warning signals of non-point source pollution risks.The analysis of the intensity of the pollution from the source based on the coupling of satellite remote sensing and Statistical Yearbook is helpful to the simulation of the regional pollution in large-scale farming area,and is conducive to formulate targeted solutions and measures according to the pollution level,and provides theoretical basis and new ideas for the green and healthy development of ecological environment in the cultivated areas.