Study On Non-point Source Pollution Models Based On RS And GIS

Three Gorges Watershed is not only the soil erosion districts of the middle and upper of the Yangtze River where environmental is the most fragile, but also the water resource key protection zone made by the State Council, after point source pollution had been get control step by step, the influence of the not-point source(NPS) pollution began to show , and become the important fountainhead of water environmental pollution gradually, especially after Three Gorges reservoirs established, the environment of water and soil will occur great change , will make its face with more and more big pressure of NPS pollution, therefore, for Three Gorges Watershed, spread out the NPS pollution research has not only important realistic meaning, but also social value.This paper adopt the research method of " dot area combination "and " macroscopic microscopic combination ", with the model simulated method based on remote sensing and GIS , microscopically analysised and calculated & imitated quantificationally the NPS pollution status of the Three Gorges Watershed and its typical sub-catchments, that is Yulin river in Yubei district. Chongqing city. Furthermore , after further investigated and researched the driving force of NPS pollution, put forward the best management practices (BMPs) , accordingly made the NPS pollution research systematic, overall and profound. The paper had gotten following accomplishment mainly:( 1 ) From the 1995 to 2000, the change condition of major influence factor of NPS pollution in Three Gorges Watershed. Land use&cover change(LUCC) is mainly displayed as woodland degeneration and plowland occupied by construction , woodland degeneration is displayed as conversion of forestland into construction land, of forestland into shrubs and of grassland into forestland , at the same time, in some places, the situation that ecological recovery had taken place was also arisen ,this is displayed as conversion of grassland info forestland. Such changes indicate that, in recent years, the ecological environment in the Three Gorges Watershed was worsening on the whole, except some local areas; Vegetation coverage increases somewhat, but current vegetation coverage is more little than the requirement of controlling NPS pollution ; Soil loss aspect, results showed that annual average soil erosion amount was 3012.6t/km~2.a, and the highest place is as high as 9000 t/km~2.a, meanwhile, the category of erosion degree is displayed as light degree taked 14.79%,...