Come early to Costa Mesa to take advantage of pre-conference workshops! Planning is under way for some great topics including:

  • The SWMM5+ Hydraulics Engine Workshop
  • Urban Flooding Analysis using PCSWMM and EPA SWMM5

Scroll down on this page to find out more!

The SWMM5+ Hydraulics Engine Workshop: an in-depth review of new code 


This 4-hour pre-conference workshop will introduce participants to the structure and capabilities of the beta release for the new open-source, finite-volume, hydraulics solver that works as a plug-in to EPA-SWMM v5.1. The working name for this pre-release model is SWMM5+. The new model is designed for parallel processing on systems ranging from laptop computers to cloud supercomputers. In addition to faster runtimes from parallelization, the new finite-volume hydraulics algorithms improve mass conservation and solution stability when transitioning from open-channel flow to surcharged flow. 

The goals of the workshop are: 

  • Provide insight into the new data structures for the hydraulic solver, 
  • Explain the new finite-volume algorithms for open-channel and surcharged flow, 
  • Demonstrate compiling of the mixed-language C/Fortran code with Fortran coarrays, 
  • Provide understanding of what parallelization can and cannot do for SWMM, 
  • Illustrate new capabilities and high-resolution data available from the finite-volume solution,  
  • Discuss development of the new Application Programming Interface (API). 


  • The workshop will consist of four 45-minute sessions with 15-minute breaks between sessions.  
  • Sessions 1-3 will be lectures and demonstration of the code structure and the model. 
  • In the 4th session the participants will be able to download executables and the source code. Session organizers will help participants compile and execute the model on their laptop machines (Mac, Linux, PC).  


The EPA-SWMM5 code is written in C, but the new parallel SWMM5+ solver is written in CoArray Fortran (CAF), which is a 2008 addition to the Fortran standard. The SWMM5+ module must be compiled with the C source code of EPA-SWMM 5.1 as a mixed-language model. This approach was chosen over the more conventional use of C with MPI for parallel programming due to the simplicity of CAF in handling Single Program Multiple Data (SPMD) parallelism. A further feature in returning to Fortran is in the use of array processing in the code. Thus, the new SWMM5+ avoids “do-loops” over space by using array statements, e.g., a(x) = b(x) + c(x) adds b to c for all elements of vector x without requiring a do-loop. Coders with experience in Matlab or NumPy will be familiar with array processing, although they may not have worked with the CAF version. The use of array processing places greater emphasis on the data structures used to define the solution vector spaces. Thus, a key goal of this workshop is to provide coders with an introduction to the underlying philosophy and methods used in the new SWMM5+ data structures. This introduction will be particularly useful to those wrapping the EPA-SWMM code within other models. 

Who is the organizer? 

Professor Ben R. Hodges (University of Texas at Austin) is the Principal Investigator for the National Center for Infrastructure Modeling and Management (NCIMM), a 5-year project funded at $4 million by the US EPA to develop next generation advances for stormwater modeling that has produced the SWMM5+ engine. He is a tenured Professor in the Civil, Architectural, and Environmental Engineering Department (CAEE) at UT Austin. His research is focused on water flow in natural and man-made environments, including flood analyses, storm water systems, river flows, lake dynamics, estuary circulation, and oil spill modeling. Research contributions include (i) new computational methods for efficient simulation models, (ii) geospatial analyses for translating high-resolution data (e.g. lidar) to practical model scales, (iii) wrapper systems for running multi-model simulations for oil spill uncertainty analyses.

Find out more: 

Ben Hodges UT Austin Faculty Profile 

Ben Hodges personal web page 

Edward Tiernan is a Ph.D. student at the University of Texas at Austin (expected graduation May, 2022). He earned a B.S. in Civil and Environmental Engineering from the University of Virginia in 2016, and his M.S. at UT Austin in 2018 with a thesis on optimization techniques for calibrating storm water models. His PhD research has focused on strategies for enhancing the parallelizability of urban water models. As the senior PhD student in the NCIMM program, he coordinates work among other students on the SWMM5+ development team and plays a central role in testing and validation of the new computational engine.

Who should attend? 

The workshop is targeted at researchers and industry professionals who work directly with the SWMM C code to expand its capabilities and/or wrap the code into other models. Participants should be comfortable looking at code and understanding data structures.  Some familiarity with numerical algorithms will be useful, but is not required. 

Persons who are primarily interested in the capabilities and potential applications of SWMM5+ are encouraged to attend the SWMM5+ presentation in the regular technical sessions (New modeling capabilities with the SWMM5+ parallel hydraulic solver) and the 1-hr Workshop on community-driven open-source SWMM, where next?  

In-person or Online? 

The workshop is currently planned for in-person attendance.  

When is it?  

Sunday Jan. 9, 2022, 9 am – 1 pm Pacific. Transportation between the conference hotel and the workshop venue, lunch and refreshments will be provided. 

How do I register and what is the cost? 

Registration is via EventBrite. Follow the links on the conference Registration page. Tickets are available for US$60. 

Please email us at if you have questions. 

Urban Flooding Analysis using PCSWMM and EPA SWMM5


This specialized PCSWMM and EPA SWMM5 workshop is intended for both new and experienced modelers with the objective of building skills in modeling surface overflows from urban drainage systems. It focuses on the essential methodologies and considerations for analyzing urban flooding within PCSWMM. General flow routing and control concepts are presented, along with the specific case of inlet control (i.e., conveyance capacity restrictions due to curb inlets/catchbasin grates). Concepts will be reinforced using a series of related hands-on exercises that compare peak flood stages, hydraulic gradeline profiles, and flood inundation extents using a variety of approaches.

PCSWMM will be used throughout the workshop to speed learning and program execution and enhance the understanding of the underlying EPA SWMM5 processes. Participants will develop the necessary skills and confidence to effectively explore and apply the official EPA SWMM5 hydrology/hydraulics engine. During this course you will have an opportunity to learn from live instructors during scheduled live sessions.


  • The workshop will be entirely virtual and will consist of two 2-hour sessions with hands-on exercises and breaks between each session.
  • Topics include 1D flood analysis, integrated 1D-2D modeling, and overland flow modeling.
  • An optional post-workshop Q&A session will be included at the end of the schedule.
  • Two instructors will be available during both sessions.


In constrained urban areas, quantifying and evaluating overland flow routing can be challenging. Characterizing urban flooding requires detailed hydraulic modeling, often via coupling a one-dimensional (link-node) model with a two-dimensional (mesh) representation of the ground surface. Integrated 1D-2D models can be used to assess floodplain inundation when watercourses overflow their banks or when the conveyance capacity of pipe networks is exceeded, and the hydraulic gradeline reaches the ground surface. Understanding these models can aid engineers in identifying flood risk, especially in situations where the flood flow paths are not clearly defined or consistent between flood events, such as in unconstrained areas where there are multiple flow paths around obstructions (e.g., buildings, walls, etc.).

Who is the organizer?

Computational Hydraulics International (CHI) has been developing and supporting professional software systems for stormwater management and wastewater/watershed modeling since 1978. Located in Ontario, Canada the CHI office is staffed by 15 employees, including five engineers and five software developers/programmers. For more details, please visit our website at



Mike has over 30 years of experience in water resources planning, analysis, design, program financing, and policy development. He has developed hydrologic and hydraulic models for over 100 stormwater analysis and design projects and specializes in continuous simulation for water balance calculations, non-point source water quality loading, sizing of sediment removal and rainwater harvesting facilities, and assessment of watercourse and wetland impacts. He has also assisted with the development of and technical support for stormwater modeling software. Mike has been a lead author and researcher for many peer-reviewed technical papers and publications, and has presented and lectured at conferences, seminars, training workshops and universities world-wide.


Hailiang is a licensed professional engineer in Ontario with over 10 years of experience and has expertise in modeling for various applications. Prior to joining CHI, Hailiang was a water resources modeling specialist with GHD. He has applied modeling techniques for various hydraulic structures design analysis and environmental assessment studies. His expertise includes 1D, 2D, and 3D hydrodynamic and water quality modeling for riverine/lake systems, hydraulic modeling for stormwater, and sanitary sewer systems. In CHI, he has developed design storms under climate change conditions for a few projects, peer-reviewed models, and created innovative solutions through computer programming. Hailiang has also led the development and documentation of the PCSWMM Python scripting support, developed script importers to import other software models into PCSWMM/SWMM or EPANET projects. He created a Civil3D plugin to exchange data between PCSWMM and Civil3D software smoothly. Hailiang has published over 15 scientific papers and acts as peer-reviewer for three technical journals.

Who should attend?

The workshop is designed for beginner to intermediate-level modelers ideally with some experience with PCSWMM or EPA SWMM5. Supplementary materials will be made available for beginners to complete before the workshop, including SWMM5 hydrology and hydraulics video presentations and a short hands-on exercise intended to familiarize one with the PCSWMM interface.  

In-person or online?

The workshop is currently planned for virtual attendance only.

What’s included?

Attendees will each receive a 60-day PCSWMM 2D workshop license upon registration. Course login information will be provided 1-week before to the workshop. Attendees will have permanent access to the course, provided they have a valid PCSWMM license. Once logged into the course, live sessions, presentations, demonstrations, and hands-on exercises are accessible through the course schedule.

If an attendee cannot make it to one of the live presentations, links to pre-recorded videos will be made available sometime after the presentation.

When is it?

Saturday, January 8th, 2022, 8:00 am – 12:00 pm Pacific.

How do I register and what is the cost?

Registration is via EventBrite. Follow the links on the conference Registration page. Tickets are available for US$45.