OpenSWMM Application Manual

See Authors & Contributors for the full list of authors and contributors.

DISCLAIMER

This software is provided on an "as is" basis and the user assumes responsibility for its use. Although a reasonable effort has been made to assure that the results obtained are correct, the authors are not responsible and assume no liability whatsoever for any results or any use made of the results obtained from these programs, nor for any damages or litigation that result from the use of these programs for any purpose.

ACKNOWLEDGEMENTS

The original SWMM 5 Applications Manual was prepared by Lewis A. Rossman, Environmental Scientist Emeritus, U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory. His foundational work in providing practical application examples for SWMM is gratefully acknowledged.

See Authors & Contributors for the complete list of authors and contributors.

Introduction

This manual answers one question: which formulation should this model use, and what changes if you pick another one?

OpenSWMM offers more than one representation of nearly every process it models — four flow routers, four pressurisation closures, three transport engines, three two-dimensional momentum closures, two groundwater models. The reference manuals derive them and the Engine Manual gives their grammar. Neither tells a modeller facing a surcharging trunk sewer which one to reach for, or what the answer would have been under the other.

So this manual is built from decision workflows and worked examples rather than from a tour of the software:

Chapter 1 is six decision workflows — routing, pressurisation, the 2D surface, transport, age and heat, groundwater — each ending at the literal [OPTIONS] lines that select a formulation, and a table naming every formulation's keys, status, theory and worked example.
Chapters 2 to 11 are worked examples. Each names an in-tree deck under docs/figures/decks/, shows the options that select the formulation, runs the same model under the alternatives, and reports what changed. Every figure in them is generated from those runs.
Chapter 12 runs the same models from Python and from plugins.
Chapter 13 is what is coming, and is careful to present nothing planned as if it worked today.

Each worked chapter keeps the same five headings — Problem, Deck, Options that select the formulation, Results, Where to go next — so a reader looking for one of them can find it without reading the rest.

How to read a result here. Every comparison in this manual is between runs of the same deck with one group of keys changed. Where two formulations disagree, the chapter says which one is believed and why — against a measurement, an analytic solution, or a conservation argument — rather than presenting the difference as a matter of preference.

Where the SWMM 5 Applications Manual topics went

The EPA SWMM 5 Applications Manual was a tour of the interface built around one site. That ground is now covered by the GUI tutorials, and this manual covers the formulations instead.

Former chapter	Now
Ex. 1 – Site Drainage	T1 — Site Drainage with Water Quality
Ex. 2 – Surface Water Quality	Chapter 8: the three transport engines, and Chapter 3 - Surface Buildup for the theory
Ex. 3 – Runoff Water Quality	Chapter 4: Surface Washoff
Ex. 4 – Low Impact Development	Section: [LID_USAGE] for the grammar and Chapter 6: Low Impact Development Controls for the theory
Ex. 5 – Continuous Simulation	Chapter 11: long-term hydrology
Ex. 6 – Detention Pond Design	not yet rewritten; the EPA SWMM 5 Applications Manual remains the reference
Ex. 7 – Combined Sewer Overflow	not yet rewritten; the EPA SWMM 5 Applications Manual remains the reference
Ex. 8 – Real-Time Control	not yet rewritten; the EPA SWMM 5 Applications Manual remains the reference

Manual Contents

Chapter 1: Choosing a Formulation — Chapter 1: Choosing a Formulation
Chapter 2: A Filling Pipe under the Dynamic Wave and Finite-Volume Routers — Chapter 2: A Filling Pipe under the Dynamic Wave and Finite-Volume Routers
Chapter 3: A Sub-Atmospheric Transient — the Slot against the Two-Component Pressure Approach — Chapter 3: A Sub-Atmospheric Transient
Chapter 4: Virtual Junctions on a Surveyed Trunk — Chapter 4: Virtual Junctions on a Surveyed Trunk
Chapter 5: Street Inlets and the Inlet Junction — Chapter 5: Street Inlets and the Inlet Junction
Chapter 6: Building a Coupled One- and Two-Dimensional Model — Chapter 6: Building a Coupled One- and Two-Dimensional Model
Chapter 7: Rain, Infiltration and Groundwater on the Mesh — Chapter 7: Rain, Infiltration and Groundwater on the Mesh
Chapter 8: The Three Transport Engines — Chapter 8: The Three Transport Engines
Chapter 9: Multi-Species Reactions — Chapter 9: Multi-Species Reactions
Chapter 10: Water Age and Heat — Chapter 10: Water Age and Heat
Chapter 11: Long-Term Hydrology — Chapter 11: Long-Term Hydrology
Chapter 12: Running Models from Python and Plugins — Chapter 12: Running Models from Python and Plugins
Chapter 13: What Is Coming — Chapter 13: What Is Coming