25. SWMM Introduction#
The EPA Storm Water Management Model (SWMM) is a comprehensive software tool developed by the U.S. Environmental Protection Agency for simulating the quantity and quality of stormwater runoff in urban areas. First developed in 1971, SWMM has become one of the most widely used models for planning, analyzing, and designing urban drainage systems, including storm sewers, combined sewers, and other conveyance systems. Its ability to simulate dynamic rainfall-runoff relationships, along with pollutant transport, makes it a key tool for engineers working on stormwater management, flood control, and water quality improvement projects.
SWMM allows users to model the physical processes involved in stormwater runoff, including rainfall, infiltration, evaporation, and surface flow, as well as the behavior of drainage networks under varying conditions. The model supports continuous or event-based simulation, which enables long-term studies of stormwater systems under different climate conditions. Additionally, SWMM includes a variety of features for modeling green infrastructure practices such as permeable pavement, rain gardens, and green roofs, which are essential for sustainable stormwater management. Its versatility and ability to incorporate both conventional and innovative infrastructure make it an invaluable tool for engineers tasked with addressing complex urban water challenges.