Storm Rainfall-Runoff Quality Analysis of Typical Catchment Using SWMM

Abstract

The RUNOFF block of EPA's storm water management model (SWMM) was used to simulate the quality of urban storm water runoff from relatively small site in Beijing. We monitored and sampled runoff during several storm rainfall events and analyzed the concentration of total phosphorus (TP), nitrate nitrogen(NO3-N), ammonia nitrogen(NH4-N), lead (Pb), copper(Cu), zinc(Zn) and cadmium(Cd) totally seven indicators, which were used for calibration of the model. Application of the model was done using the Green-Ampt equation for infiltration loss computation, a pollutant accumulation equation using a saturated build-up equation, and a power wash-off equation dependent on the predicted runoff rate. Complete rainfall events were used for verification of the model, which showed a good comparison with observed data for pollutant loadings. The results of this study suggest that SWMM can express in detail the storm water pollution patterns from diverse rainfall scenarios in Beijing, and pollution loading has a positive correlation with rainfall intensity.