Abstract:In order to analyze the non-point source pollution of the typical watershed in the Feilaixia Reservoir area, an experiment of water quantity and quality monitoring in each rainfall events in Shegang watershed was conducted, and non-point source pollution load was estimated by mean concentration method, analyzing the pollutant characteristics of runoff from different rainfall events and calculating the contribution rate of non-point source pollution. Simulation of runoff and non-point source pollution was made by using SWAT model. The results show that: runoff plays a dominant role in the concentration and load of SS, BOD5, etc. ; the initial scouring effect of TN and NH3-N is obvious; the correlation between pollutant load and runoff is better than that between pollutant concentration and runoff; the contribution rate of non-point source pollution of pollutants is more than 80%. The efficiency coefficients of SWAT model for runoff simulation in calibration and validation periods are 0. 85 and 0. 73, respectively, showing that the SWAT model has good accuracy. In the pollutants calibration period, typical daily pollutants with strong rain have the best simulation effect, with the relative error of pollutants within 10%. When the rain intensity is low, TN and TP are underestimated to a large extent. In the pollutants validation period, since it is in the spring ploughing and fertilizing period, the relative errors of TN and TP simulation results are large and underestimated. In general, SWAT model has good simulation accuracy, which can basically reflect the non-point source pollution situation in the basin, and can provide reference for non-point source pollution simulation and control in the Feilaixia Reservoir Basin.