A Modeling Method to Evaluate the Management Strategy of Urban Storm Runoff

Design of treatment strategy considering the behavior of pollutant with respect to runoff hydrograph is important for effective management of storm runoff. In this study, a mathematical model for storm runoff management was developed. The model determines the storm runoff management strategy and the associated probability under the constraint of regulatory discharge limit, and can quantify the volume or fraction of a storm runoff that should be treated. The model application was demonstrated for total suspended solids (TSS) and benzo(a)pyrene (BaP) in urban storm runoff. The samples were collected from 15 storm runoff events in six impervious sites in Beijing urban area, and. For TSS, the probability that the whole runoff can be discharged without treatment was 46 %, and the whole runoff should be intercepted for treatment was 31 %. While under the constraint of the discharge limit for BaP, the dominant strategy was that the whole runoff should be intercepted for treatment, with a probability of 88 %. Compared with the treatment strategies, it was noted that the need for runoff treatment was more for BaP than TSS. This was because the pollution level of TSS was lower than BaP from the aspect of compliance with discharge limit. Because the most seriously contaminated and toxic pollutant should be taken as the primary indicator for runoff treatment, the treatment option for the study area should follow the strategies for BaP. This methodology may be applied for other pollutants in different watersheds.