The study analyzed how urban features, sewer systems, and rainfall affect runoff water quality using a model called SWMM. They found that different areas and sewer systems influence runoff rates and pollutant levels. Areas with combined sewers manage runoff better during light rain but have higher pollution during heavy rain. Placing green infrastructure (like gardens and filters) strategically can help control water flow and pollution. For example, combining sewer systems with distributed green areas is effective. In areas with separated sewers, concentrating green infrastructure at the basin's end works well. This research helps plan ways to manage water in cities and minimize pollution.