Partition And Classification Control Scheme Of Agricultural Non-Point Source Pollution In Anji County

Agricultural non-point source pollution has become the focus of attention,because of its serious harmfulness and complex features.And how to effectively control of agricultural non-point source pollution,has also been the research focus of scholars in international and domestic.This research through the field investigation in Anji County and collected the related information,and identified the main pollution factors of Anji County.And on this basis to establish the applicable to SWAT model and WASP model of Anji County,then divided Anji County into 61 sub basins,and visual displayed the spatial distribution of agricultural nitrogen and phosphorus loss of Anji County river basin,and accounted out the corresponding sub basin water environmental capacity under the different water quality goals.On this basis,combining with the relevant planning of Anji County,non-point source pollution of partitioning scheme is proposed by adopted the way of secondary partition.Anji County in the primary partition,be divided into three zones,they are Upstream ecological environment protection and water and soil nitrogen and phosphorus loss control area,Midstream non-point source pollution comprehensive control area and Downstream pollution reduction and ecological restoration control area.According to the characteristics of the distribution of pollution sources in Anji County and the requirements of water functional areas performed a secondary partition.Then proposed the agricultural non-point source pollution control plan for Anji County,which provided the basis and thought for the effective control of agricultural non-point source pollution in Anji County.The main conclusions are as follows:1.From 2010 to 2014,in addition to individual cross-section,the other sections of Anji County,the water quality indicators are in line with the requirements of water functional zoning.Taking the water quality standard of class II as a reference,it can be concluded that in all pollution factors beyond the Class II,the average overtaking rate of DO,ammonia,total phosphorus,permanganate index and CODcr in all the pollutants exceeding Grade ? water were 5.73%and 15.32%,6.63%,1.47%,4.39%respectively.In all sections beyond Grade ? water quality,ammonia nitrogen and total phosphorus exceeded the most,accounting for 64%.2.Based on Arcgis software,SWAT model spatial database and attribute database are constructed,and the parameterization process of watershed space is realized by data transformation.Through the calibration and verification of the model of Hengtang hydrological station and Chaitanbu water quality monitoring site,it is concluded that the correlation coefficient between the calibration and the verification period for the runoff of Yungang hydrological station can reach above 0.9,and the correlation coefficient between ammonia nitrogen and total phosphorus in Chaitanbu water quality monitoring site can also be about 0.8.The efficiency coefficients of the three variables also meet the requirements of the model,indicating that the SWAT model has good applicability in Anji County.At the same time,SWAT model simulation results show that nitrogen and phosphorus load from upstream to downstream showed a gradual increase in the trend,and continue to accumulate in the downstream area,so the load is several times upstream.3.Based on the output of SWAT model,use the obtaintion of the ammonia nitrogen and total phosphorus pollution load of each sub-basin in month scale as the input of simulated pollution load of WASP model,and the water environmental capacity of Anji County was calculated.Through the verification of the model of Hengtang hydrological site and Jingwan water quality monitoring station,the consistency coefficient between runoff and ammonia nitrogen was above 0.9,the total phosphorus was 0.86.The correlation coefficient of the three variables was 0.8 or more,indicating that the WASP model appropriate in Anji County.The calculation results of water environmental capacity show that most of the river sections of Anji County basically meet the requirement of water functional zoning,but there are still some remaining water environmental capacity of some sub-watersheds.4.According to Anji County administrative division,topography,population distribution,land use,per capita arable land distribution and the combination of "Anji County Environmental Functional Zoning","Anji County Soil and Water Conservation Plan",divided Anji County into the three major control Area.And according to the type of pollution within the control area for secondary division,which divided into the Pollution priority control area,Tea planting pollution control area,Food crop cultivation pollution control area,Breeding pollution control area,Urban life pollution control area,Eco-tourism pollution control area,Eco-environmental protection control area and Water purification and repair control area.And then according to the characteristics of agricultural non-point source pollution in each secondary control area,combined with field reconnaissance and analyze the main problems,finally put forward the targeted agricultural non-point source pollution control scheme in Anji County.