The Study Of Non-point Source Pollution Based On The Isotopic Traceability And Landscape Pattern Analysis Of Qing River Watershed

Qing river basin is an important branch of Liao river upstream inTieling, the basin area is 5.14 X 10 km, the water quality conditions directly affects agricultural production and the water environment security downstream in the basin. Basin is given priority to with the first industry, although in recent years, the trend of water environment pollution is in contained, he proportion of the non-point source pollution is increasing in water environment pollution,and it will lay a foundation for the control of non-point source pollution to carry out the stduy on the historical changes of non-point pollution, the pollution source and space-time distribution in the basin. This study analyzed the development law of non-point source pollution in Qing river basin based on the isotope tracer technique and analysis of landscape pattern. And get the simulation parameters that appled to the simulation of the non-point source pollution in Qing river watershed by verifing the applicability of SWAT model. Through analyzing historical data, measured data of water quality of Qing river watershed, simulated the non-point source pollution load contribution rate on different landscape on the basic of the analysis of watershed landscape change, and used the CLUE-S model to simulate the situation of landscape in Qing river basin in the next 10 years,at the same time, combining the load of non-point source pollution on different landscape types which came from the SWAT simulation, simulated the development trend of non-point source pollution in Qing river watershed in the next 10 years.And provide the reference to landscape layout reasonable, controling non-point source pollution and protecting the water environment. The specific research contents and results are as follows:1) Analyzed tne general law of non-point source pollution in Qing river watershed through arranging nearly 20 years of date on water quality monitoring stations in the basin, and setted the sample points to investigate the condition of non-point source pollution in the basin in 2004. The result shows the water quality of Qing river is better now, the pollution situation is much better of upstream than that of downstream, and is greatly influenced by the seasons. The main pollution elements is nitrogen in the river basin. From the the determination results of the sediment, we find that there is signs of accumulation of pollution, and tne water quality is closely associated with the surrounding environment.2) Using TM remote sencing images and topographic map as the data sourcess, classified and interprted the landscape types of Qing river basin in 1986 and 2014, and analyzed the landscape pattern charecteristics of dynamic change from 1986 to 2014. Paddy field landscape has increased by 15.278%, residents and industrial land increased by 13.584%and 18.091%respectively, and gathered from scattered to distribution. A 28.201%reduction was in dry land,woodland reduced by 0.764%and water area decreased by 23.445%.3) From the landscape pattern index analysis, we know taht the landscape patch density index, landscape diversity index and fragmentation index decreased, and the advantage of woodland increased and was more connectivity; Landscape heterogeneity degree declined,landscape type has the development trend of simplification and non-equilibrium.4) After SWAT model parameters calibration, used the data of sediment and run off from 2003 to 2010 to simulate and verify on SWAT model. Simulated and analyzed the non-point source pollution of Qing river basin on SWAT model. The amount of sediment yield is 117509.523 tons, the total nitrogen is 662.37739 tons and the total phosphotous is 175.234 tons. The largest contribution on these load is the paddy field.5) Using nitrogen stable isotope tracer technique to measured the nitrogen isotope deteminnation of the samples, indicated that the amount of 515N downstream is higher than upstream,there are six sample pionts of all nine points whose the amount of 515N is in+9%o-+20%o, displaying that large amounts of nitrogen pollution in the Qing river basin came from sewage and fertilizer. Therefore there need to control sewage and industrial wastewater emissions and the use of fertilizers. Accoding to the simulation results on CLUE-S land scape model, the landscape area of paddy field will gradually increase, and its contribution to the pollution load is highest, so the amount of sediment and total nitrogen pollution load will be increased, thus need to reasonably control the spacial distribution of paddy field and the fertilizer usage in paddy field.