Study On Non - Point Source Pollution In Dianchi Lake Basin Based On 3S Technology

In the basin of Dianchi area, with the growth of population and the rapid development of economic, there are more and more pollutants and eutrophic substances discharging into the Dianchi Lake, which extremely damaged the balance of its ecological environment, reduced the ecological environment’s purification capacity, and then aggravated the water pollution of Dianchi Lake. The pollution of Dianchi Lake has not only seriously restricted the improvement of Kunming residents’ quality of life, but also influenced Kunming’s Economic Sustainable Development. So it’s imminent to bring the pollution of Dianchi Lake under control.This essay uses the worldview-2 remote sensing image as its data sources, and after investigating the non- point source pollution’s characteristic and its generating path of the basin of Dianchi area, we determine to research the east and south bank of the basin of Dianchi area. Under the support of RS technology, we preprocess the data sources, and get the high resolution remote sensing image. GPS makes an positioning analysis of the rainfall stations, pipeline nodes and sewage treatment plants, so we take advantage of the analysis; at the same time, the ArcGIS software is excellent enough in processing the data, so that we extracted the parameters required by the SWMM (Storm Water Management Model), and then input related data into the SWMM model. At last, we determine the model’s parameters according to the measured rainfall data in the east and south bank of the basin of Dianchi Lake and some related research experience; then carry out an simulation analysis of the pollution load of non-point pollutant (COD、TN、TP) in the east and south bank of the basin of Dianchi Lake. Our main research findings are as follows:(1)In the different rainfall intensity of 2008(high flow year),2011(low flow year) and 2013 (normal flow year), we respectively carry out an simulation analysis of the east and south bank of the basin of Dianchi Lake. In 2008, the simulation runoff amount of systematic rainfall is 267.271 million m3,the output of COD、TP and TN are respectively 34593.70 tons,1545.96tons and 5653.36 tons; in 2011, the simulation runoff amount of systematic rainfall is 53.07million m3, the output of COD,TP and TN are respectively 21526 tons,490 tons and 3688 tons; In 2013, the simulationrunoff amount of systematic rainfall is 126.31 million m3, the output of COD% TP and TN are respectively 34593.70 tons,1545.96tons and 5653.36 tons. By comparison, we find, under certain conditions, the amount of runoff produced by rainfall and the pollutants are proportional to rainfall.(2)According to our comparison and analysis, under the rainfall condition of rainfall reappearance period of 0.5a,1a,5a and 10a, the volume of runoff and the total amount of pollutants in different areas are decreased as follows:the south bank of Jincheng area, the east bank of Luolong river area, the south bank of Gucheng area, the south bank of Kunyang area, the east bank of Guangpu Dagou Maliao river area and the Laoyu river area. And under the rainfall condition of different rainfall reappearance period, the total volume of runoff in every area increases with the increasement of rainfall, and as a general rule, the output of pollutants(COD,TN and TP) also increases with the increasement of rainfall.(3)Under the rainfall condition of rainfall reappearance period of 0.25a,0.5a, la and5a, we carried out an simulation analysis of the Luolong river sewage treatment plant, finding that:at the beginning of rainfall, the pollutants increase with the increasement of rainfall, it is to say that, the first flush effect is much more obvious. The rainfall is the key factor in affecting the first flush effect.