SWMM User Guide

"The SWMM Version 2 User’s Manual introduces one of the earliest comprehensive mathematical models for simulating urban stormwater runoff and combined sewer overflow (CSO) processes. It establishes the foundational framework for representing runoff generation, transport, storage, and treatment systems. This version also incorporates early methods for estimating treatment efficiency, system performance, and receiving water quality impacts. While it lacks modern capabilities such as continuous simulation and dynamic hydraulic routing, it serves as a critical foundation for all subsequent SWMM developments."

"The SWMM Version 3 User’s Manual expands on earlier modeling capabilities, supporting simulation of urban runoff quantity and quality in storm and combined sewer systems. It introduces more detailed computational blocks such as Runoff, Transport, and Storage/Treatment, along with supporting tools for system analysis and statistics. Compared to Version 2, it improves hydrologic and hydraulic representation, though it still relies on a modular structure rather than a fully integrated modeling framework."

"The EXTRAN Addendum for Version 3 introduces the Extended Transport (EXTRAN) module, enabling dynamic flow routing in urban drainage systems. It allows simulation of unsteady flow conditions, including backwater effects and surcharging, by representing systems as interconnected nodes and links. This addendum provides the theoretical and numerical foundation for modern dynamic wave routing used in later SWMM versions."

"The SWMM Version 4 User’s Manual advances the model with a more structured and flexible modular framework for simulating urban hydrology, hydraulics, and water quality. It includes detailed descriptions of key program blocks such as Runoff, Transport, Storage/Treatment, and Combine, along with system analysis tools. This version improves input/output handling, expands modeling capabilities, and supports multiple computing platforms, making it a major step toward modern stormwater modeling systems."

"The EXTRAN Addendum for Version 4 provides advanced guidance on dynamic hydraulic routing for complex drainage networks. It explains how unsteady flow, backwater conditions, and surcharging are simulated in pipes and open channels using numerical methods. This document is essential for detailed hydraulic analysis and forms the technical basis for later integrated routing approaches."

"The SWMM 5.0 User’s Manual marks a major transition to a fully integrated hydrologic–hydraulic modeling system with a graphical user interface. It enables simulation of urban runoff quantity and quality using a structured and flexible modeling framework. The manual covers model setup, input data, hydrologic and hydraulic processes, and result visualization. Version 5.0 significantly improves computational efficiency, usability, and consistency compared to earlier modular versions."

"The SWMM 5.1 User’s Manual builds on Version 5.0 with improved representation of urban drainage processes and enhanced modeling accuracy. It introduces better street drainage modeling, improved stormwater treatment options, and more accurate subcatchment calculations. These enhancements increase model reliability and performance for complex urban systems."

"The SWMM 5.2 User’s Manual provides comprehensive guidance on simulating urban stormwater systems, including rainfall–runoff processes, hydraulic routing, and water quality analysis. It supports both single-event and continuous simulations using an integrated modeling framework. This version introduces enhancements such as improved stormwater inlet capture modeling, more robust hydraulic routing, and better input/output handling. These updates improve model stability, scalability, and usability for large and complex urban drainage systems."