How to Use Population for DWF in SWMM5 and InfoSWMM

The SWMM5 engine uses mean flow as the dry weather flow value (DWF) and not population but does allow weekday, weekend, daily and monthly patterns. You can use these many pattern options to actually use population in the SWMM5 and InfoSWMM dry weather flow tables. Here are the steps as … Read the rest

Treatment in BMP’s and LID’s for SWMM5

Treatment in BMP’s and LID’s

5.1 Treatment

Excerpt from the EPA manual Storm Water Management Model Reference Manual Volume III – Water Quality (PDF) which can be found here

5.1.1 Background

Management of stormwater quality is usually performed through a combination of so-called “best management practices” (BMPs) and a form … Read the rest

Refactoring the SWMM 5 Help File – RDII in SWMM5


Unit Hydrographs

Unit Hydrographs (UHs) estimate rainfall-dependent inflow/infiltration (RDII) into a sewer system. A UH set contains up to three such hydrographs, one for a short-term response, one for an intermediate-term response, and one for a long-term response. A UH group can have up to 12 UH … Read the rest

Refactoring the SWMM 5 Help File – SWMM5 Introduction

Introducing EPA SWMM5

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 … Read the rest

Refactoring the SWMM 5 Help File – Snowmelt in SWMM5

Snowmelt in SWMM5


Snowmelt parameters are climatic variables that apply across the entire study area when simulating snowfall and snowmelt. They include:

· the air temperature at which precipitation falls as snow
· heat exchange properties of the snow surface
· study area elevation, latitude, and longitude correction.

See Read the rest

Refactoring the SWMM 5 Help File – Tools in SWMM5

Tools in SWMM5

Using Add-In Tools

SWMM 5 has the ability to launch external applications from its graphical user interface that can extend its capabilities. This section describes how such tools can be registered and share data with SWMM 5.

Tools Menu

The Tools Menu contains commands used to configure … Read the rest

Refactoring the SWMM 5 Help File -Editing in SWMM5

Editing in SWMM5

Working with Objects

SWMM uses various types of objects to model a drainage area and its conveyance system. This section describes how these objects can be created, selected, edited, deleted, and repositioned.

· Types of objects
· Adding objects
· Selecting an object
· Moving an object
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Refactoring the SWMM 5 Help File – Routing in SWMM5

Routing in SWMM5

Flow Routing

Flow routing within a conduit link in SWMM is governed by the conservation of mass and momentum equations for gradually varied, unsteady flow (i.e., the Saint Venant flow equations). The SWMM user has a choice on the level of sophistication used to solve these equations:… Read the rest

Refactoring the SWMM 5 Help File – Output in SWMM5

Output in SWMM5

Viewing Simulation Results

This section describes the different ways in which the results of a simulation can be viewed. These include a status report, a summary report, various map views, graphs, tables, and a statistical frequency report.

Viewing a status report

Viewing a summary report

Variables that Read the rest

Refactoring the SWMM 5 Help File – Climate Data in SWMM5

Climate Data in SWMM5


The Climatology object in EPA SWMM describes the following climate-related variables used for computing runoff and snowmelt:

· Temperature
· Evaporation
· Wind Speed
· Snowmelt
· Areal Depletion
· Climate Adjustments
Rain Gages

Rain Gages supply precipitation data for one or more subcatchment areas … Read the rest

Refactoring the SWMM 5 Help File – Groundwater in SWMM5

Groundwater in SWMM5


Aquifers are sub-surface groundwater zones used to model the vertical movement of water infiltrating from the subcatchments that lie above them. They also permit the infiltration of groundwater into the drainage system, or exfiltration of surface water from the drainage system, depending on the hydraulic gradient … Read the rest

Refactoring the SWMM 5 Help File – Non Visual Objects in SWMM5

Non-Visual Objects in SWMM5

Non-visual Objects

In addition to physical objects that can be displayed visually on a map, SWMM utilizes several classes of non-visual data objects to describe additional characteristics and processes within a study area.

· Climatology Data
· Hydrology Data
· Hydraulic Data
· Water Quality Data
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Refactoring the SWMM 5 Help File – Nodes in SWMM5

Nodes in SWMM5


Nodes are points of a conveyance system that connect conveyance links together. There are several different categories of nodes that can be employed:

· Junctions
· Outfalls
· Flow Dividers
· Storage Units

Nodes are also the points where external inflows can enter a drainage system … Read the rest

Refactoring the SWMM 5 Help File – Water Quality in SWMM5

Water Quality in SWMM5

Water Quality Modeling Features

In addition to modeling the generation and transport of runoff flows, SWMM can also estimate the production of pollutant loads associated with this runoff. The following processes can be modeled for any number of user-defined water quality constituents:

· dry-weather pollutant buildup
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Refactoring the SWMM 5 Help File – Hydrology in SWMM5

Hydrology in SWMM5

Hydrologic Modeling Features

SWMM accounts for various hydrologic processes that produce runoff from urban areas. These include:

· time-varying rainfall
· evaporation of standing surface water
· snow accumulation and melting
· rainfall interception from depression storage
· infiltration of rainfall into unsaturated soil layers
· percolation
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