Integrated Assessment of Non-point Source Pollution in Songhuajiang River Basin

On the basis of the opportunity of National Water Resource Planning in China,the loads of non-point source pollution were calculated in Songhuajiang River Basin in Northeast China in 2000.The work was finished by a model called binary structure model based on the data collection and investigation in the study area,additionally with the assistance of 3S technology.This model was set up by simplifying the process of pollutants transported of non-point source pollution.We divided the factors which affected the fate of pollutants into 2 categories;one is natural factors,the other social parameters.The most particular characteristic is that the dynamic factor,precipitation runoff factor was included in the equation.The model was applied in basin after calibration and validation.Then an assessment of non-point source pollution condition was presented.The results indicate: the load of TN,TP,and NH+4-N almost came from agricultural fields(70% for these 3 pollutants),but livestock and rural residential contributed the most COD load(95%) among the 4 type′s pollution sources,i.e.,agricultural farm,livestock farm,rural residential areas and urban areas.The load of TN,TP resulted from non-point source pollution(about 61% of the sum) is larger than that from point pollution,in which the load of TP is about 10 times more than that from point pollution.The relationship between the loads of COD and NH+4-N from non-point source and point pollution sources is opposite.The load of COD,TN,TP,and NH+4-N from 4 type pollution sources presents a temporal and spatial characteristic in distribution.In general,the load transported during flood season(from June to September) is larger than that during drought period(December to next April).And the pollutants from non-point source pollution dispersed in the Songnen Plain in the Songhuajiang River basin and the Nenjiang River basin.