Simulation Of Non-point Source Pollution Of River Sinuosity In Yixing Based On HSPF Model

For a long time, point source pollution was considered to be the main cause of water pollution. Our country spent a lot of money and used a variety of techniques to reduce sewage discharge, which achieved certain achievement. However, simple point source control cannot improve water quality fundamentally.A large number of non-point source pollutants continually dispersed into the water, which has become a new class of sources.Non-point source pollution comes mainly from municipal sewage,livestock and poultry breeding and farming activities, agricultural nonpoint source pollution(ANPSP) is the most the most important and most widely distributed non-point source pollution. Recent years, nonpoint source pollution has become an important issue of common concern in the domestic environment field, owing to its high randomness, wide range of time and space, long latency period and complicated formation causes.In this paper, the study area is plain river network of Yixing, Yixing located in the south of Jiangsu Province and the west bank of Taihu Lake, where economic developed rapidly. There are 37 industrial point sources and two sewage treatment plantslocated in the study area. By investigating, 95% of the industrial point source emissions in the study area have entered the sewage treatment plant. To investigate the river water quality of Yixing region, the paper chose caoqiao River and yincungang village as the research objectf, and we laid seven sampling pointsat caoqiao River, laid seven sampling points at yincungang village, laid eight sampling points at the into lake ports. From May in 2013 to March in 2014, we sampledsix times, once every two months, and measured water temperature and conductivity measurementson-site, and analysised of ammonia, nitrate, TN, TP, CODMn, chlorophyll, TOC, and other three-dimensional fluorescence in the laboratory. For natural geographical environment, climate characteristics and basin runoff modeofplain river network in Yixing, selected the HSPF model to calculatie non-point source pollution of plain river network in Yixing, and by field researching, data collecting, builtspatial and attribute database of HSPF model successfully in plain river network ofYixing, established HSPF model, and calibrated and verificatedthe area runoff, sediment load of total phosphorus and total nitrogen from 2011 to 2013. In this study, the following conclusions:(1) The experimental results show caoqiao River and yincungang Village from upstream to downstream, TP, TN, ammonia concentration increased, the TP, TN, ammonia nitrogen pollution of caoqiao River worse than yincungang Village,and the COD pollution levels in yincungang village more serious than caoqiao River. Taihu estuary each point along the coast from north to south, TP concentration gradually increased, TN and ammonia concentration decreases, COD did not change significantly. The pollution levels of TP,TN and ammonia nitrogen in Taihu Lake is lower than the river, but the degree of pollution of COD is higher. In 22 sampling points, the concentration of TP reached a maximum 0.46 mg / L in July and the concentration of TN reached a maximum 8.5mg / L in March.(2) Using ArcGIS, BASINS and other tools to build a spatial database and attribute database of HSPF model, and establish HSPF model in Yixing plain river network of Taihu Lake Basin area, and study the runoff, sediment and total nitrogen and total phosphorus module for calibration and validation. Using relative error(RE) and Nash coefficient(Ens) to simulate the effect of the model were evaluated. The simulation results show that the average relative error of annual runoff is 10.8%, Ens is 0.872; The average relative error of sediment is-23.83%- 44.85%; the average relative error of ammonia is-31.3%; and the average relative error of total phosphorus is-27.69%. HSPF model ability to simulate runoff better, to simulate the effect of sediment total phosphorus and total nitrogen in general. Overall, the simulation accuracy of HSPF model basically meet the requirements, can be used to simulate the non-point source pollution of Yixing plain river network area.(3)Uncertainty analysis of the model are as follows: In the meteorological input data model, the rainfall and potential evapotranspiration for non-point source pollution load simulation is most sensitive. Due to the length,section width, and slope of the rivercalculated by DEM elevation data are different from the actual values, but the nature of the data directly affect the river simulate river runoff, reducing the model simulation accuracy. The sediment is related to land-use types and soil types in the study area, and the set parameters of sediment comes from the sand analysis in the study area, so the simulation of sediment varied greatly.Therefore, the result of this thesis provides a reference for Taihu Lake Basin’s non-point source pollution research and controlling, and also acts as reference in other regions’ non-point source pollution research. This research has important scientific significance and broad application prospects.