| With the increasing pollution control of point source, the proportion of non-point source pollution (NSP) load compared to total pollution load is gradually rising and its influence becomes more and more outstanding. As a result, the quantification of NSP becomes vital important for water pollution control and water environment comprehensive management. However, the complexity of source, ambiguity of mechanism and latency of formation for NSP makes it difficult to quantify it. On the basis of investigation and monitoring, combining with the technology of'3S', this paper takes the Jinghe river watershed as an example to study this problem. Firstly, during flood and non-flood period in 2009, water quality and quantity at the Zhang Jiashan section of the Jing river were monitored, Secondly, taking the Jinghe river watershed in Shannxi province as the example, simulation and prediction of NSP for watershed under different data conditions is studied, also, the characterristic of NSP and its proportion compared to total pollution load are analyzed. Under the limited data condition, the adaptability and reliability of SWAT model in the Jinghe river basin are repectively studied by means of GIS. This research is not only important to comprehensively understand the cause of water pollution of the Jinghe river, but also important to water environment comprehensive management and water resources protection of it.The study methods and results can give references for other similar region and watershed. To sum up, main results of this study are listed as follows:1. In 2009, four storm events and three 24 hours normal flow events at the Zhang Jiashan section were monitored; clarified water quality of them was analyzed. The results indicate that: during the flood, the concentrations of COD, TP as well as TN are higher than those in the non-flood period. The high values of the COD, TP and TN are related to natural humic substance in the surface layer soil. The total-N is mainly made of dissolved nitrogen, and total-P is mainly made of particle phosphorus. TP, TN and COD are closely related with flow.2. Mean concentration method and runoff division method were used to estimate NSP weighted mean concentration for each element. Water quality and quantity correlation method was used to establish correlation equation between NSP load and surface runoff for each element. The calculated NSP mean concentration and the established correlation equation are used to estimate NSP load of the Zhang Jiashan section in the Jinghe River, the results of the two methods prove to be credible. The annual NSP load proportions compared to the total of the Zhang Jiashan section are calculated in 2009. The effect of NSP to water quality is serverely.3.Jinghe river basin is selected as the study area, SWAT model is applied to simulate the producing and transporting process of flow, sediment and nitrogen non-point source pollution. Monthly flow, sediment and nitrogen pollutant data series from 1996 to 1999 are used to calibrate and validate the correlative parameters of monthly flow and sediment. The nitrogen and phosphorus pollutant data series from 2005 to 2006 are used to calibrate and validate model. The results of calibration and validation show that the model is reasonable and available. The calibrated model is used to calculate the loadings of non-point source pollutants of different typical years. Based on the simulated results, the spatial and temporal distribution of flow, sediment and non-point source pollution has been analyzed for the non-point source pollution control.
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