Analysis On Features Of Non-point Source Pollution In Chaohu City And Research On Load Simulation

With the continuous development of cities, the waterproof surface is enlarging in buildings and roads. Accordingly, the area of green space and the trees is decreasing, which aggravated the problem of the urban non-point source pollution. Because of complexity of formation, the difficulties of the transferential process of non-point source pollution and randomness, as well as the time consuming artificial monitoring process, non-point source pollution problem is arousing more and more attention. The simulation research of agricultural non-point source pollution for the future of agricultural non-point source pollution control and governance is of great significance. In this background, this article takes Chaohu city old city as the research object, based on the analysis of the surface of the local features and collection of related data, the author of the dessertation use SWMM software to establish the perfect Chaohu city old city as non-point source pollution model.And the reliability of the model is verified by the real rainfall data.Through the three land use types of study area(commercial, residential, park), and its surface field sampling, analysis of particle size,analysis of heavy metal content,analysis of 24 hour leaching liquid, it is concluded that grain size in 150 ~ 300 um the most proportion of the surface of particles, an average of about 65%, particle size of more than 300 um accounted for nearly 15%, particle size of less than 150 microns accounts for nearly 20%.Analysis of heavy metal shows three land use types are presented under the same quality about small particles of the heavy metal content is higher, this is due to the smaller grain size. the greater the specific surface area and thus the greater the adsorption capacity,so there is the smaller the particle size, the more its heavy metals.24 hour of surface leaching liquid of supernatant fluid of COD, TN and TP content test results can be concluded that in the commercial, residential, park three land use types of leaching liquid in commercial district has the highest leaching liquid contaminants(389mg/L COD, TN 18 mg/L, TP 1.1 mg/L), residential high(346 mg/L COD, TN 13 mg/L, TP0.8 mg/L), and park of leaching liquid content lowest 256 mg/L(COD, TN 7 mg/L, TP 0.4mg/L).Model from the different rainfall intensity of water simulation analysis can be concluded that the different rainfall intensity from producing pollution discharge amount have bigger difference, the greater the rainfall intensity produced by the flow rate and thegreater the pollutants, rainfall intensity, the more heavy rain, the greater the peak rainfall per unit time, the greater the into the river COD, TN and TP concentration was greater;Under different rainfall intensity, but its flow in the same change trend, into the river under different rainfall intensity change trend of COD, TN, TP is basically the same.For the water quality of water under different land use types of simulation can be concluded that, under different land use types the production flow of the production quantity also is have bigger differences, maximum flow and pollutants produced by commercial district, residential areas times, areas of traffic and pollution are small. Peak,per unit time of rain, the rain into the river COD, TN and TP concentrations are commercial> residential > park; But its flow under different land use types have the same change trend, into the river under different land use types change trend of COD, TN, TP with the same trend.