Study On Output Characteristics Of COD Form Agricultural Non-point Sources In Fuyang City Based On ArcGIS

In this paper,the export coefficient model was used to determine the COD pollution load of agricultural non-point source in all counties and districts of Fuyang City,and the contribution of agricultural non-point source COD pollution and the spatial and temporal distribution characteristics of COD load in the basin were studied.Based on the topographic map,the land use map and the water system map,the correlations between COD concentrations and landscape pattern indicators of different land use types were studied under different land use patterns such as waters,residential land,forest land,garden land and cultivated land.At the same time,by introducing rainfall factors,topographic factors,surface runoff factors and underground storage factors,the effects on the water body coefficients were studied.Results were listed as follows:(1)The pollution source load of Linquan County was the highest in Fuyang City.Linquan County was selected as the main research object.The difference of COD concentration in different monitoring points of rivers in Linquan County was obvious,and COD pollution was more serious form March to July.(2)The land use type was residential land,and the COD concentration was significantly negatively correlated with COHESION(P?0.05).The land use type was forest land,and the COD concentration was significantly positively correlated with ENNMN(P?0.05).The land use type was garden,and the COD concentration was significantly positively correlated with PD and COHESION(P?0.05),significantly positively correlated with SHAPEMN(P?0.01).Which showed that the more dispersed the residential land,the greater the isolation of the forest land,the more complex the shape of the garden,The greater the concentration of COD in the basin.The land use type was cultivated land and waters,and there were no significant correlation between COD concentration and various landscape pattern indicators.For the principal component analysis of water quality and environmental factors,8 principal components were obtained,which could explain the variance of 93.996%(3)This paper introduced the effects of rainfall,topography,surface runoff and underground infiltration factors on the inflow coefficient.Establishing a regression equation for the annual influx of rivers and annual average rainfall of agricultural surface source COD pollution load in Linquan County,the function had a good fitness(R~2=0.7494).The interpolation factor of ArcGIS spatial analysis module was used to obtain the influence factor of agricultural surface source COD into the river in the study area.There were great differences in the factors affecting the COD inflow coefficient of agricultural non-point sources in different years.There was also spatial heterogeneity in different regions of the same year.The relative deviation of the simulation results decreased from 6.21 to 0.21 during the observation period before and after the improvement,which improved the accuracy of the estimation results in general.Figure[39]table[32]reference[92]...