Small Watershed Non-point Source Pollution Export Analysis System Construction

Non-point source pollution is very serious in China, it is one of the key factors that affect water quality. To understand the characteristics of small watershed runoff can provide theoretical support for non-point source pollution. In this paper, through analyzing the characteristics of agricultural non-point source pollution area of North Tiaoxi watershed and the water quality variation of time and space distribution and quantitative evaluation, we get the water quality variation factors.Also through optimization mathematical method of pollution sources to get the export coefficient, then account nitrogen and phosphorus loss of the typical non-point source pollution area. Small watershed non-point source pollution export analysis system is obtained based on the method of nitrogen and phosphorus loss calculation programming. At last, this research provides certain scientific basis for controlling non-point source pollution. Mainly the following results are obtained:Based on the analysis of the temporal and spatial variation of water quality in this area, the land use pattern is the most important factor to the water quality variation by the correlation analysis and stepwise regression analysis. Among them, Farmland% had a great influence on the COD and Turbidity in the study area. Urban% was the impact factors of T?DO?EC?TOC?COD?NH4+-N?NO3--N?TN?TP. Forest% was significantly negative correlation with COD, Water% was the impact factor of DO, T, DTP water quality index. The effect of landscape pattern on water quality showed that the patch density was the impact factor of DO?EC?TOC?COD? N03--N?TN?TP?DTP. In addition to patch density, other landscape pattern indexes were not significantly correlated with water quality index. Social and economic factors to water quality impact results showed that:PPUA and EOPUA were significantly correlated with pH and Turbidity.With the results of water quality research, land use, rural life and other pollution sources were selected. In the typical agricultural area source pollution area called Quanchenwu in North Tiaoxi, the 5 section water quality of the basin and the rainfall were monitored, combined with flow accounting, the total amount of TN, TP of rainfall was 14.41t,0.85 t in 2014. Based on the measured data and the export coefficient method, the TN and TP export coefficients of the pollution sources were calculated by the optimization method. The simulation accuracy of TN and TP load were 80.52% and 82.90% respectively. The export of TN in the river basin was 75.82%, and the export of forest land was 20.01%, and the export of forest land was 49.16%, and the export of TP was 21.35%.In the agricultural area source pollution export analysis system, the main factors of agricultural non-point source pollution are selected from 12 sources, such as land use and rural life. The whole system divided into starting selection module, coefficients accounting elements module, load calculation module, removal rainfall load calculation module, sampling module of regional information, nitrogen and phosphorus pollution coefficient calculation module, export module that mounted seven modules. Matlab and Visual Studio joint as programming realization were used in small watershed non-point source pollutant export analysis. Through the third chapter of the total nitrogen, regional basic situation and other data were put into this system, the system analysis results was in line with the actual results. Then it showed that the export of the small watershed non-point pollution analysis system had a certain practicality.