Simulation Of Non-Point Source Pollution On The Basin Of Chaohe River By HSPF Model

Based on the non-point source (NPS) pollution model HSPF ( Hydrological Simulation Program-Fortran ), which was chosen as the research tool in this paper, carried out model input,optimization of model parameters and uncertainty analysis research on the Chaohe River basin. Using calibrated and verified model, quantitative evaluation of non-point source pollution load, summarized the law of temporal and spatial variation of non-point source load in the basin, completed the analysis of non-point source control scenarios. The main conclusions are as follows:(1) A relative error (RE) and the Nash-Suttcliffe efficiency coefficient (Ens) were calculated to evaluate applicability of HSPF model, the efficiency coefficients for the simulation of stream flow, sediment loads and nutrients loads were 0.87, 0.76, 0.79~0.85 accordingly. The results show that the HSPF model is well fitted for the long-term non-point source pollution simulation in the study area.(2) Uncertainty of input data analysis results are as follows: eight meteorological input parameters, only rainfall and potential evapotranspiration data on non-point source load is more sensitive. Rainfall and potential evapotranspiration system error on non-point source pollution load of a similar nature are the greatest uncertainties in the sand, followed by TP load, river flow and TN load. For the same type of non-point source pollution, rainfall on the non-point source pollution load of potential evapotranspiration is greater than its impact.(3) By using of HSPF model, on the basis of setting up the spatial database and attribute database, completed the calibration and validation of non-point source pollution model, quantitative evaluated the load of non-point source pollution from 1998 to 2003 and calculated the contribution rate of sources to Chaohe River Basin, summarized the law of temporal and spatial variation of non-point source load in the basin. The results showed that sediment, TN, TP were the primary non-point source pollution, the load of pollutant load in 2003 were: TN: 2319.44 t/a, TP: 21.15 t/a, SS: 324.18 t/a. The main sources of pollution can be classified as excessive use of fertilizers, human and animal waste pollution, rural production and living waste water and solid waste pollution. The non-point source pollution load which inflow from Chaohe River into Miyun reservoir mainly in flood season, especially in wet and normal water years, the loss of sediment in flood season accounted for more than 82 % throughout the year; the load of nitrogen in dry season accounts for about 39~47 % , normal and wet water accounts for 65~81 %; the load of total phosphorus in dry season accounts for about 32~45 %, while normal and wet water account for 55~72 % . (4) Design scenarios to control the non-point source pollution based on the situation ofnon-point source pollution of Chaohe River Basin,①25°above slope farmland return to forest;②15 ~ 25°slope farmland turn into the orchard;③25°above the slope grassland turn to forest;④1 ~ 15°slope farmland set contour hedgerow;⑤Cut off livestock pollution 50 %;⑥Fertilization rate decrease from 50 % to10 %;⑦set vegetation protection zone in the sensitive areas of rivers and reservoirs. Compared of the seven scenarios for total nitrogen, total phosphorus reduction by using the model and then determined the best management practises.