The Storm Water Management Model (SWMM) is a computational software tool widely used for planning, analysis, and design of stormwater runoff, sanitary sewer, and combined sewer systems. It was developed by the Environmental Protection Agency (EPA) and is commonly applied by engineers and environmental scientists for urban water management projects.
Key Features of SWMM
- Hydrology Simulation:
- Simulates rainfall-runoff processes for urban and rural catchments.
- Models surface and subsurface hydrology, including infiltration, evaporation, and groundwater flow.
- Hydraulics Modeling:
- Analyzes flow in natural channels and stormwater or sewer pipes.
- Includes dynamic routing for open channel and closed conduit flow.
- Pollutant Transport:
- Tracks pollutants in stormwater runoff.
- Models water quality impacts of urban runoff on receiving water bodies.
- Control Features:
- Simulates real-time control of hydraulic structures like pumps, gates, and weirs.
- Scenarios and Design Alternatives:
- Enables evaluation of green infrastructure practices such as permeable pavement, rain gardens, and infiltration trenches.
- Supports “what-if” analyses to optimize stormwater management strategies.
Applications of SWMM
- Urban Flood Modeling: Identifies areas prone to flooding and designs mitigation strategies.
- Stormwater System Design: Helps design new stormwater infrastructure or retrofit existing systems.
- Combined Sewer Overflows (CSO) Management: Assists in controlling overflow events in combined sewer systems.
- Water Quality Management: Evaluates impacts of stormwater runoff on surface water quality.
- Green Infrastructure Planning: Assesses the effectiveness of sustainable drainage systems.
Strengths of SWMM
- Open Source and Free: Freely available with comprehensive documentation.
- Customizable: Allows users to develop custom scripts or extend its functionality.
- Widely Used: Recognized as a standard tool by many municipalities and agencies.
- Detailed Analysis: Provides detailed temporal and spatial resolution for simulation results.
Inputs to SWMM
- Rainfall Data: Time-series data of rainfall intensity or hyetographs.
- Catchment Characteristics: Information on land use, soil properties, and topography.
- Hydraulic Infrastructure: Details of conduits, manholes, channels, outfalls, and storage units.
- Water Quality Data: Parameters for pollutant generation and transport.
Outputs from SWMM
- Flow rates, velocities, and depths in hydraulic networks.
- Flooding volumes and locations.
- Water quality indicators such as pollutant concentrations.
- Performance metrics for system components.
Common Tools and Interfaces
SWMM has a graphical user interface (GUI) that allows users to build models visually. It also supports input and output in text-based formats for advanced users.
For more information and downloads, you can visit the EPA SWMM website.
