A Study Of Agricultural Non-point Source Nitrogen And Phosphorus Pollution Modelling And Process Into The River In The Dongliao River Basin

Non-point source pollution is a common form of pollution, more attention waspaid to environmental problems with the development of economy. Research onagricultural non-point source pollution is also gradually thorough because of itsextensive distribution, and also difficult to quantitative monitoring,effectively controland so on,non-point source pollution has become the emphasis and also the difficultyin the management. There is a large rural population scale in our country, theagricultural non-point source pollution has become the main pollution. DongliaoRiveris a major tributary of the LiaoRiver, the agricultural non-point source pollution ismore serious in recent years. As the problems of the water environment andagricultural non-point source pollution is there, in this paper, investigation was carriedon the pollution of plantation, husbandry and rural life. By building the spatial andattribute database, a research on agricultural non-point source pollution simulationwas done with the aid of the distributed hydrological model called SWAT, then basedon the sediment load, total nitrogen and total phosphorus pollution load obtained inthe study area, we analyze the temporal and spatial distribution of the sediment, totalnitrogen and total phosphorus pollution load combining with Arcgis spatial processingcapabilities, and also calculate the rate loss of those pollutants into the river basin, themain study results obtained were as follows:1Based on statistical yearbook data of Jilin province and Jilin provincepollution census database data, a research on the pollution of plantation, husbandryand rural life was done to calculate pollution load. The yearly average of nitrogen andphosphorus pollution load produced by pigs, sheep, cattle and poultry was reduced inturn in the study area. The nitrogen and phosphorus content in the sewage and humanwaste has estimated in the basin. The yearly average nitrogen content in life sewage is12.09kg hm-2a-1, content of phosphorus is1.06kg hm-2a-1.The content of nitrogen in the feces is7423.95kg hm-2a-1and the content of phosphorus is1713.22kg hm-2a-1, the content of nitrogen is significantly higher than that of phosphorus.2A model was set up to simulate agricultural non-point source pollution, therunoff, sediment, and pollutant observed data used belongs to Quantai hydrologicalstation.By combining the SWAT model parameter sensitivity analysis results with theparameter analysis, calibration and validation functions of the SWAT–CUP software,the content of runoff, sediment and pollutant was calibrated and validated during thecalibration and validation period, the correlation coefficients,Nash-Suttclife efficiencyfactor, relative errors between the observed and the simulated data could satisfy therequirements of model precision and suitability evaluation,as well as the totalnitrogen and total phosphorus.Thus the parameters could be applied to simulate theagricultural non-point source pollution of the basin.3After statisticing and analyzing the pollutant output of the SWAT model, wefind that the changing rules of sediment load, total nitrogen and total phosphoruspollution load from2006to2010were similar with a rising trend except in2009, thepollution load is reduced. The sediment, total nitrogen and total phosphorus pollutionload is relatively high from May to September in each year, in July of the2007,2008and2010, the sediment load, total nitrogen and total phosphorus pollution load is themax among twelve months of the year, the pollution load is larger in wet season.Thepollution load of Gongzhuling city, Yitong County and Liaoyuan city near the sourcearea is larger from2006to2010. The total phosphorus pollution load is bigger in themiddle and lower reaches of the area, while the northern Gongzhuling city and theeastern Lishu county is heavier.4Base on the SWAT model simulating output,the rate loss of the yearlyaverage sediment load, total nitrogen and total phosphorus pollution load wasobtained by means of statistical interpolation methodof Arcgis, and study the processof pollutants into the river. The rate loss of the sediment in the study area is largeroverall, which is between0.70and0.80,and increase from southeast to northwest. Thespace distribution characteristics of total nitrogen rate loss are similar to the totalphosphorus, which is between0.50and0.70.However, the middle and lower reachesof the study area is higher. Compared to rate loss of the total nitrogen, the total phosphorus is slightly lower which between0.40and0.60, and increased from thesoutheast to the northwest.The study comprehensively reveal the research area’s sourceof agriculturalnon-point, quantity, agricultural non-point source pollution load and the spatialdistribution characteristic of pollutants rate loss,and put forward the correspondingprevention measures and suggestions, thus providing reliable basis for agriculturalnon-point source pollution control of Dongliao River.