The EPA Storm Water Management Model (SWMM) is a dynamic rainfall-runoff simulation
model used for single event or long-term (continuous) simulation of runoff quantity and quality
from primarily urban areas. The runoff component of SWMM operates on a collection of
subcatchment areas that receive precipitation and generate runoff and pollutant loads. The routing
portion of SWMM transports this runoff through a system of pipes, channels, storage/treatment
devices, pumps, and regulators. SWMM tracks the quantity and quality of runoff generated within
each subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel
during a simulation period comprised of multiple time steps.
SWMM was first developed in 19711 and has undergone several major upgrades since then2. It
continues to be widely used throughout the world for planning, analysis and design related to
storm water runoff, combined sewers, sanitary sewers, and other drainage systems in urban areas,
with many applications in non-urban areas as well. The current edition, Version 5, is a complete
re-write of the previous release. Running under Windows, SWMM 5 provides an integrated
environment for editing study area input data, running hydrologic, hydraulic and water quality
simulations, and viewing the results in a variety of formats. These include color-coded drainage
area and conveyance system maps, time series graphs and tables, profile plots, and statistical
frequency analyses.
This latest re-write of SWMM was produced by the Water Supply and Water Resources Division
of the U.S. Environmental Protection Agency's National Risk Management Research Laboratory
with assistance from the consulting firm of CDM, Inc