Application of SWMM in the simulation of point source pollution in a macrodrainage system

Abstract

Many cities in Brazil still present, in some locations, flaws in the urban drainage system, mainly concerning water contamination by punctual and diffuse sources, with drainage channels visibly contaminated by domestic sewage and solid waste. Therefore, the present study aimed to perform the diagnosis of dry weather flows and evaluate the behavior of pollutant concentrations during the propagation of the flow and the response of mathematical modeling to an intervention proposal in case the punctual entries that present greater polluting potential to be removed, aiming at improving the quality channel waters. The identification of the sewage entry points in the Canal do Prado was based on field observations. The flow measurement was made at each selected point, to better understand the flow behavior and obtain a good average for the analyzed period. To perform the simulation, the concentrations of the variables BOD, COD and FT for the sewage inlets were raised. A diagnosis of dry weather flows was carried out, corresponding to the reality of the drainage system in the non-rainy periods of the city. The results indicate that SWMM responds well to the Dry Climate Flow (DWF) simulation. Furthermore, even small interventions done in the canal would not yield a significant improvement in the overall quality of the drainage system of the basin, the improvements would be only local.