| Rural non-point source(NPS) pollution has become the main source of pollutionthat affect the water quality of the environment, with great harm to the rivers,reservoirs and other water bodies. Because of its randomness, hysteresis, uncertaintyand long-term, etc. The monitoring and forecasting to it is quite difficult, meanwhilethe corresponding research and controlling work is relatively lagging, with has notbeen paying attention enough, which is urgently in need of the related technicalsupport. Therefore, the rural nps pollution load accounting is quite worthy to studied.The main contents of this paper as follows:(1) The rural NPS pollution estimation methods were studiedThe quantitative estimation methods of the agricultural NPS pollution load wasstudied, then three kinds of general methods under different conditions are integrated,according to the condition of data and technology. The properties of commontechnology under different data conditiongs are discussed, on the basis of theirprinciple and characteristics. At last, the general calculation methods of NPSpollution load of rural domestic waste and livestocks raising were established.(2) The output characteristics of a typical small watershed NPS pollution wereanalysed.Si Heshui catchment in Tanjiang basin was chosen as a water monitoringwatershed. Several synchronous monitoring of water quality and quantity had beendone at Shuangqiao hydrological station which is the outlet of the watershed, and theproduction process and characteristics of NPS pollution were analysed by theobservation data.(3) The simulation models of the watershed in the study region were built by HSPFmodel, and their results were analysed.Firstly, the observation data of water quantity and quality were used for thecalibration and validation of HSPF model. Then the model method was applied to thebasin with Shengtang cross-section in Tan Jiang as outlet. The daily process of NPS pollutant in the watershed with Shengtang cross-section as outlet was simulated, thenthe spatial distribution of each pollutant flux in the main river was analysed. Thecontribution rate from forest land and agricultural land to each pollutant is the biggestin the various land use types, according to the2010annual NPS loads resulted fromthe basin report exported by HSPF model. From the output amount of per unit area ofNPS pollution load on the different types of land use in2010, it can be seen that thehighest load of per unit area of various pollutant is output from agricultural land orbuilding land, in the contrary the least load is output from waterarea or barren land.(4) Each rural NPS pollution load of Shengtang and Niuwan cross-section wasestimated.2010agricultural NPS annual load of Shengtang cross-section control catchmentwas calculated by using the HSPF model simulation, and each2010NPS annual loadof the rural domestic waste and livestocks raising by using the pollution outputcoefficient method and statistics was calculated. Then the rural NPS pollution annualload into the river of Shengtang cross-section control catchment were calculated asthe sum of above. The rural NPS pollution annual load into the river of Niuwancross-section control catchment were calculated as the same way as those ofShengtang cross-section control catchment, besides the2010agricultural NPS annualload was calculated by export coefficient method which based on the HSPF model. Atlast, Each total watershed pollution load into the river of Shengtang and Niuwancross-section were calculated by various sources of pollution load, then they werecompared with the measured flux. It can be found that most relative errors of thepollution load estimation with observation are below30%. |
PDF Full Text Request