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EPANET

Original author(s)	Lewis A. Rossman
Developer(s)	United States Environmental Protection Agency (USEPA, Cincinnati, Ohio)
Stable release	2.0.12 / Feb 14, 2008
Development status	Active
Written in	C Programming Language(engine) / Object Pascal(User Interface)
Operating system	Windows
Available in	English
Type	Engineering Simulation
License	None(Public domain)
Website	www.epa.gov/nrmrl/wswrd/dw/epanet.html

EPANET is a public-domain, water distribution system modeling software package developed by the United States Environmental Protection Agency‘s (EPA) Water Supply and Water Resources Division. It performs extended-period simulation of hydraulic and water-quality behavior within pressurized pipe networks and is designed to be “a research tool that improves our understanding of the movement and fate of drinking-water constituents within distribution systems”.^[1] EPANET first appeared in 1993.^[2]

EPANET 2 is available both as a standalone program and as an open-source toolkit (Application Programming Interface in C). Its computational engine is used by many software companies that developed more powerful, proprietary packages, often GIS-centric. The EPANET “.inp” input file format,^[3] which represents network topology, water consumption, and control rules, is supported by many free and commercial modeling packages. Therefore, it is arguably considered as the industry standard.

Features [edit]

EPANET provides an integrated environment for editing network input data, running hydraulic and water quality simulations, and viewing the results in a variety of formats. EPANET provides a fully equipped and extended period of hydraulic analysis that can handle systems of any size. The package also supports the simulation of spatially and temporally varying water demand, constant or variable speed pumps, and the minor head losses for bends and fitting. The modeling provides information such as flows in pipes, pressures at junctions, propagation of a contaminant, chlorine concentration, water age, and even alternative scenario analysis. This helps to compute pumping energy and cost and then model various types of valves, including shutoffs, check pressure regulating and flow control.

EPANET’s water quality modeling functionality allows users to analyze the movement of a reactive or non-reactive tracer material which spreads through the network over time. It rates the reactive material as is grows, tracks the percentage of flow from the given nodes. The package employs the global reaction rate coefficient which can be modified on a pipe-by-pipe basis. The storage tanks can be modeled as complete mix, plug flow or two-compartment reactors.

The visual network editor of EPANET simplifies the process of building piping network models and editing their properties. These various types of data reporting visualization tools are used to assist to analyze the networks, which include the graphics views, tabular views, and special reports.

Hydraulic simulation [edit]

Headloss in pipe segments [edit]

EPANET hydraulics engine computes headlosses along the pipes by using one of the three formulas:

• Hazen-Williams formula: used to model full flow conditions under simplified conditions (turbulent flow, temperature around 60 degrees Fahrenheit, and viscosity similar to water) http://www.epa.gov/nrmrl/wswrd/dw/epanet.html
• Darcy-Weisbach formula: used to model pressurized flow under a broader range of hydraulic conditions
• Chezy-Manning formula: used to model open channel flow

Since the pipe segment headloss equation is used within the network solver, the formula above is selected for the entire model.

Head-flow Curves of Pumps [edit]

Within EPANET, pumps are modeled using a head-flow curve, which defines the relationship between hydraulic head imparted to the system by the pump and flow conveyed by the pump. The model calculates the flow conveyed by the pump element for a given system head condition based on this curve. EPANET can also model a pump as a constant power input, effectively adding a given amount of energy to the system downstream of the pump element.^[3]

Network solver [edit]

The network hydraulics solver employed by EPANET uses the “Gradient Method” first proposed by Todini and Pilati,^[4] which is a variant of Newton-Raphson method.

Water-quality simulation [edit]

EPANET includes the capability to model water age and predict flow of non-reactive and, under simplified conditions, reactive materials.^[3] This capability is frequently used to predict chlorine residuals within water distribution systems. While the internal water quality simulation capabilities only evaluates decay or growth of a single constituent, an extension is available (EPANET-MSX), which allows modeling of interactions between constituents.

EPANET Toolkit [edit]

EPANET’s computational engine is available for download as a separate dynamic link library for incorporation into other applications.^[5] The source code for EPANET 2 is available on the EPA’s EPANET website.^[6]

Compatibility [edit]

EPANET uses a binary file format, but also includes the capability for importing and exporting data in dxf, metafile, and ASCII file formats. EPANET’s ASCII file format is called an input file within EPANET, and uses a file extension “.inp”.^[3] The input file can include data describing network topology, water consumption, and control rules, and is supported by many free and commercial modeling packages.

While EPANET is used as the computational engine for most water distribution system models, most models are developed and maintained in hydraulic modeling packages based on EPANET’s computational engine. Some of the major hydraulic modeling packages are:

• H2OMap, H2ONet, and InfoWater, developed by Innovyze (formerly MWH Soft, a subsidiary of MWH)
• MIKE URBAN, developed by DHI
• WaterCAD, WaterGEMS, HAMMER and SewerCAD developed by Bentley‘s Haestad Methods (Hydraulics & Hydrology) group.
• WatDis, developed by Transparent Blue

Most of these applications allow for multiple demand conditions, planning scenarios, and various methods of integrating with other data sources an agency may already have in place not supported in EPANET, such as GIS, and support additional types of analyses not found in EPANET.

See also [edit]

Free software portal

• Hydraulics
• Storm Water Management Model
• Public domain software
• Water supply network

References [edit]

External links [edit]

• EPA Webpage (Download from here)
• EPANET on SourceForge.net – Development Repository
• Epanet and Development discussion group
• (Spanish)Epanet y Cooperación al Desarrollo (Reliefwork use of Epanet)
• (Spanish)Foro U-epanet: Epanet y Cooperación al Desarrollo (List Reliefwork use of Epanet)

Some modeling software built on this package include:

• MIKE URBAN by DHI includes customized EPANET in ArcGIS
• HydrauliCAD Info-Water by MWHsoft, runs inside AutoCAD
• Bentley WaterGEMS, from Bentley Systems, Inc
• EPAnet in Spanish
• Epanet Z: GoogleMaps, YahooMaps and Microsoft VI images within Epanet
• Free EPANET Tools
• MWH Soft InfoWater
• Download Epanet in French
• ROSIE Epanet – ArcGIS extension with increased functionality
• Pipe2010; KYPipe and Surge
• EPA-Surge EPANET Transient Analysis

EPANET
Interface do EPANET.
Desenvolvedor	Lewis Rossman
Lançado em	janeiro de 2003
Versão estável	2.00.12 (5 de março de 2008; há 271 semanas e 6 dias)
Escrito em	C (toolkit), Object Pascal (GUI)
Sistema Operacional	Multi-plataforma (toolkit), Windows (GUI)
Gênero(s)	Biblioteca de modelagem computacional
Licença	Domínio público
Página oficial	EPANET (Inglês)
Portal das Tecnologias de informação

EPANET é um programa de computador licenciado como domínio público para simulação de sistemas de distribuição de água. O software contém dois módulos integrados, que calculam a solução para o sistema hidráulico de redes pressurizadas e permitem rastrear constituintes reativos e não reativos dentro do sistema. A primeira versão do programa surgiu em 1993.

EPANET2 é a versão atual do programa, disponível tanto como um software completo quanto como um kit de ferramentas para desenvolvedores de código aberto (em C) e domínio público. A disponibilidade do toolkit fez com que o sistema se tornasse o núcleo de diversos softwares comerciais, com recursos não presentes na versão original e frequentemente focados na tecnologia GIS. O formato de entrada do EPANET, um arquivo de texto separado por tabulações de formato “.inp”, representa a topografia, consumo, controles e outros aspectos de uma rede de distribuição de água. Sua adoção por diversos outros softwares gratuitos ou comerciais tem tornado o formato um padrão de industria.

O EPANET foi desenvolvido pela Agência Norte-Americana de Proteção Ambiental (EPA – Environment Protection Agency).

Traduções para português [editar]

O EPANET possui versões em português, criadas e disponibilizadas gratuitamente por universidades brasileiras e portuguesas em código fechado.

A versão em português de Portugal, desenvolvida pelo Laboratório Nacional de Engenharia Civil, é uma tradução da versão 2.00.09, enquanto a brasileira, desenvolvida pelo Laboratório de Eficiência Energética e Hidráulica em Saneamento da UFPB (LENHS UFPB) corresponde à versão 2.00.12, mais atual disponibilizada pela EPA.

Extensões [editar]

LENHSNET é um módulo de programação, acoplado à versão brasileira do EPANET, que permite o dimensionamento hidráulico de uma rede de abastecimento de água, considerando o menor custo de investimento.

O WaterNetGen é uma extensão em inglês do EPANET para gerar modelos sintéticos, dimensionar condutas, avaliar desempenho e efectuar simulações dirigidas por pressão demanda e pressão.

Ligações externas [editar]

• EPANET (original em Inglês)
• Laboratório Nacional de Engenharia Civil EPANET em português (Portugal)
• Laboratório de Eficiência Energética e Hidráulica em Saneamento EPANET em português (Brasil)
• WaterNetGen
• EPANET Ferramentas livres

The United States Environmental Protection Agency (EPA) Storm Water Management Model (SWMM)^{[1][2][3][4][5][6][7]} is a dynamic rainfall-runoff-subsurface runoff simulation model used for single-event to long-term (continuous) simulation of the surface/subsurface hydrology quantity and quality from primarily urban/suburban areas. The hydrology component of SWMM operates on a collection of subcatchment areas divided into impervious and pervious areas with and without depression storage to predict runoff and pollutant loads from precipitation, evaporation and infiltration losses from each of the subcatchment. In addition Low Impact Development (LID) and Best Management Practice (BMP) areas on the subcatchment can be modeled to reduce the impervious and pervious runoff. The routing or hydraulics section of SWMM transports this water and possible associated water quality constituents through a system of closed pipes, open channels, storage/treatment devices, ponds, storages, pumps, orifices, weirs, outlets, outfalls and other regulators. SWMM tracks the quantity and quality of the flow generated within each subcatchment, and the flow rate, flow depth, and quality of water in each pipe and channel during a simulation period composed of multiple fixed or variable time steps. The water quality constituents such as water quality constituents can be simulated from buildup on the subcatchments through washoff to a hydraulic network with optional first order decay and linked pollutant removal, Best Management Practice (BMP) and Low Impact Development (LID) removal and treatment can be simulated at selected storage nodes. SWMM is one of the hydrology transport models which the EPA and other agencies have applied widely throughout North America and through consultants and universities throughout the world.

History [edit]

SWMM was first developed between 1969–1971 and has undergone several major upgrades since those years. The major upgrades were: (1) Version 2 in 1975, (2) Version 3 in 1981 and (3) Version 4 in 1988. The current SWMM edition, Version 5, is a complete re-write of the previous Fortran releases in the programming language C, and it can be run under Windows XP, Windows Vista and Windows 7 and with a recomplilation under Unix. The code for SWMM5 is open open source and public public domain code that can be downloaded from the EPA Web Site.

EPA SWMM 5 provides an integrated graphical environment for editing watershed input data, running hydrologic, hydraulic, real time control and water quality simulations, and viewing the results in a variety of graphical formats. These include color-coded thematic drainage area maps, time series graphs and tables, profile plots, scatter plots and statistical frequency analyses.

This latest re-write of EPA SWMM was produced by the Water Supply and Water Resources Division of the U.S. Environmental Protection Agency’s National Risk Management Research Laboratory with assistance from the consulting firm of CDM Inc under a Cooperative Research and Development Agreement (CRADA). SWMM 5 is used as the computational engine for many modeling packages plus components of SWMM5 are in other modeling packages. The major modeling packages that use all or some of the SWMM5 components are shown in the Vendor section. The update history of SWMM 5 from the original SWMM 5.0.001 to the current version SWMM 5.0.022 can be found at the EPA Download in the file epaswmm5_updates.txt. SWMM 5 was approved FEMA Model Approval Page in May 2005 with this note about the versions that are approved on the FEMA Approval Page SWMM 5 Version 5.0.005 (May 2005) and up. SWMM 5 is used as the computational engine for many modeling packages plus components of SWMM5 are in other modeling packages. The major modeling packages that use all or some of the SWMM5 components are shown in the Vendor section.

Model parameters [edit]

The simulated model parameters for subcatchments are surface roughness, depression storage, slope, flow path length; for Infiltration: Horton: max/min rates and decay constant; Green-Ampt: hydraulic conductivity, initial moisture deficit and suction head; Curve Number: NRCS (SCS) Curve number; All: time for saturated soil to fully drain; for Conduits: Manning’s roughness; for Water Quality: buildup/washoff function coefficients, first order decay coefficients, removal equations. A study area can be divided into any number of individual subcatchments, each of which drains to a single point. Study areas can range in size from a small portion of a single lots up to thousands of acres. SWMM uses hourly or more frequent rainfall data as input and can be run for single events or in continuous fashion for any number of years.

Hydrology and Hydraulics Capabilities [edit]

SWMM 5 accounts for various hydrologic processes that produce surface and subsurface runoff from urban areas. These include:

Time-varying rainfall for an unlimited number of raingages for both design and continuous hyetographs evaporation of standing surface water on watersheds and surface ponds snowfall accumulation, plowing and melting rainfall interception from depression storage in both impervious and pervious areas infiltration of rainfall into unsaturated soil layers percolation of infiltrated water into groundwater layers interflow between groundwater and pipes and ditches nonlinear reservoir routing of watershed overland flow.

Spatial variability in all of these processes is achieved by dividing a study area into a collection of smaller, homogeneous watershed or subcatchment areas, each containing its own fraction of pervious and impervious sub-areas. Overland flow can be routed between sub-areas, between subcatchments, or between entry points of a drainage system.

SWMM also contains a flexible set of hydraulic modeling capabilities used to route runoff and external inflows through the drainage system network of pipes, channels, storage/treatment units and diversion structures. These include the ability to:

handle drainage networks of unlimited size use a wide variety of standard closed and open conduit shapes as well as natural or irregular channels model special elements such as storage/treatment units, outlets, flow dividers, pumps, weirs, and orifices apply external flows and water quality inputs from surface runoff, groundwater interflow, rainfall-dependent infiltration/inflow, dry weather sanitary flow, and user-defined inflows utilize either steady, kinematic wave or full dynamic wave flow routing methods model various flow regimes, such as backwater, surcharging, pressure, reverse flow, and surface ponding apply user-defined dynamic control rules to simulate the operation of pumps, orifice openings, and weir crest levels

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 over different land uses pollutant washoff from specific land uses during storm events direct contribution of wet and dry rainfall deposition reduction in dry-weather buildup due to street cleaning reduction in washoff load due to BMP’s and LID’s entry of dry weather sanitary flows and user-specified external inflows at any point in the drainage system routing of water quality constituents through the drainage system reduction in constituent concentration through treatment in storage units or by natural processes in pipes and channels.

Low Impact Development (LID) Components [edit]

The Low Impact Development (LID) function is new to SWMM 5.0.019/20/21 and we have run many configurations and found no problem for the hydrology and hydraulics. It is integrated within the subcatchment and allows further refinement of the overflows, infiltration flow and evaporation in Rain Barrels, Vegetative Swales, Porous Pavement, Bio Retention Cell and Infiltration Trench.

You can define a variety of sub processes in each LID such as: Surface, Pavement, Soil, Storage, and Drain.

Each type of LID has limitations on the type of sub process allowed by SWMM 5. It has a good report feature and you can have a LID summary report in the rpt file and an external report file in which you can see the surface depth, soil moisture, storage depth, surface inflow, evaporation, surface infiltration, soil percolation, storage infiltration, surface outflow and the LID continuity error. You can have multiple LID’s per subcatchment and we have had no issues having many complicated LID sub networks and processes inside the Subcatchments of SWMM 5 or any continuity issues not solvable by a smaller wet hydrology time step. The types of SWMM 5 LID compartments are: Storage, Underdrain, Surface, Pavement and Soil. A Bio Retention cell has Storage, Underdrain and Surface Compartments. An Infiltration Trench LID as Storage, Underdrain and Surface Compartments. A Porous Pavement LID has Storage, Underdrain and Pavement Compartments. A Rain Barrel has only Storage and Underdrain Compartments and a Vegatative Swale LID has a single Surface Compartment. Each type of LID shares different underlying compartment objects in SWMM 5.

Integrated Hydrology/Hydraulics [edit]

One of the great advances in SWMM 5 was the integration of Urban/Suburban Subsurface Hydrology with the Hydraulic computations of the drainage network. This advance is a tremendous improvement over the separate Subsurface Hydrologic and Hydraulic computations of the previous versions of SWMM because it allows the modeler to conceptually model the same interactions that occur physically in the real open channel/shallow aquifer environment. The SWMM 5 numerical engine calculates the surface runoff, subsurface hydrology and assigns the current climate data at either the wet or dry hydrologic time step. The hydraulic calculations for the links, nodes, control rules and boundary conditions of the network are then computed at either a fixed or variable time step within the hydrologic time step by using interpolation routines and the simulated hydrologic starting and ending values.

Figure 1. SWMM 5′s QA/QC Master Example Network. This one network includes examples 1 through 7 from the SWMM 3 and SWMM 4 Manuals

An example of this integration was the collection of the disparate SWMM 4 link types in the Runoff, Transport and Extran Blocks to one unified group of closed conduit and open channel link types in SWMM 5 and a collection of Node types.

SWMM5 Components [edit]

The SWMM 5.0.001 to 5.0.022 main components are: rain gages, watersheds, lid/bmp, nodes, links, pollutants, landuses, time patterns, curves, time series, controls, transects, aquifers, unit hydrographs, snowmelt and shapes. Other related objects are the types of Nodes and the Link Shapes. The purpose of the objects is to simulate the major components of the hydrologic cycle, the hydraulic components of the drainage, sewer or stormwater network and the buildup/washoff functions that allow the simulation of water quality constituents. A watershed simulation starts with a precipitation time history.

The major overall components are called in the SWMM 5 input file and C code of the simulation engine: gage, subcatch, node, link, pollut, landuse, timepattern, curve, tseries, control, transect, aquifer, unithyd, snowmelt, shape and lid. The subsets of possible nodes are: junction, outfall, storage and divider. Storage Nodes are either tabular with a depth/area table or a functional relationship between area and depth. Possible node inflows include: external_inflow, dry_weather_inflow, wet_weather_inflow, groundwater_inflow, rdii_inflow, flow_inflow, concen_inflow, and mass_inflow. The dry weather inflows can include the possible patterns: monthly_pattern, daily_pattern, hourly_pattern and weekend_pattern.

Figure 2. SWMM 5′s LID Processes include unlimited Low Impact Development or BMP Objects per Subcatchment.

SWMM 3,4 to 5 converter [edit]

The SWMM 3 and SWMM 4 converter can convert up to two files from the earlier SWMM 3 and 4 versions at one time to SWMM 5. Typically you would convert a Runoff and Transport file to SWMM 5 or a Runoff and Extran File to SWMM 5. If you have a combination of a SWMM 4 Runoff, Transport and Extran network then you will have to convert it in pieces and copy and past the two data sets together to make one SWMM 5 data set. The x,y coordinate file is only necessary if you do not have existing x, y coordinates on the D1 line of the SWMM 4 Extran input data[ set. You can use the command File=>Define Ini File to define the location of the ini file. The ini file will save your conversion project input data files and directories.

See also [edit]

• SWAT
• WAFLEX
• DSSAM Model
• Hydrology
• Infiltration
• Hydraulics
• Surface runoff
• Drainage Basin
• Precipitation (meteorology)
• Antecedent moisture
• Evapotranspiration
• EPANET
• Rainfall
• Hydrological transport model
• Computer Simulation
• Water Pollution
• Water quality
• Surface-water hydrology

References [edit]

SWMM 5 Vendors [edit]

• InfoSWMM based on SWMM 5.0.022
• H20MAP SWMM based on SWMM 5.0.022
• PCSWMM 2011 based on SWMM 5.0.022
• SewerGEMS based on SWMM 5.0.013
• h3O based on SWMM 5.0.022
• Autodesk Storm and Sanitary Analysis based on SWMM 5.0.022
• Mike Urban based on SWMM 5.0.022
• InfoWorks Imports SWMM 5.0.022
• XP-SWMM based on SWMM 4.2
• DigitalWater CS(In Chinese) based on SWMM 5.0.022

External links [edit]

• EPA SWMM 5.0.022 page
• SWMM 3,4 to 5 Conversion Tools
• SWMM 2000+
• PAGINA DE SWMM EN CASTELLANO
• Pre SWMM 5.0.021 Installs