Water quality modelling as a planning
and management tool requires the package to be as comprehensive as possible so as to
provide necessary decision support criteria for users. The likely problems with using
continuous models such as SWMM and HSPF probably relate more to their ungainly user
interface and generally unfriendly batch input approach. When these are replaced by
graphical, knowledge-based decision support systems, most of the criticisms that these
models are too complex disappear.
Many software packages are available that address water quality issues
to varying degrees. Brief descriptions follow of what I consider to be seven useful
SWMM, HSPF, QUAL2E,
WASP, SLAMM, CORMIX,
The US EPA's Stormwater Management Model is a
comprehensive mathematical model of urban runoff quantity and pollution processes in storm
and combined sewer systems. First developed in 1971, the model has been regularly updated,
with the last major revision, SWMM4, released in 1989. It is perhaps the best-known and
most widely used of the several urban runoff quantity and quality models available in the
All aspects of the urban hydrologic and quality cycles are simulated, including surface
runoff, transport through the drainage network, storage and treatment, and receiving water
effects. The package comprises service modules and four computational modules Including
RUNOFF, TRANSPORT, Extended transport (EXTRAN) and STORAGE/TREATMENT.
SWMM is both:
- a design model which undertakes detailed simulations of storm events, using relatively
short time steps and as much catchment and drainage system detail as necessary, and
- a routine planning model, used for an overall assessment of the urban runoff problem and
proposed abatement options. This mode is typified by continuous simulation for several
years using long (e.g. hourly) time steps and minimum detail in the catchment scheme.
Continuous simulation may also be used.
Surface runoff hydrographs for individual subcatchments are generated by the RUNOFF
module via an iterative solution of coupled continuity and Manning's equations, with
infiltration represented by either Green-Ampt or Horton models. Simple routing of surface
gutter/pipe routing via non-linear reservoir routing procedure is also available in
Water quality is handled In the RUNOFF, TRANSPORT and STORAGE/TREATMENT modules,
however, WQM is not considered in the EXTRAN module.
Real storm events are modelled on the basis of rainfall (hyetograph) and pollutant
inputs and system (catchment, conveyance, storage/treatment, and receiving water)
characterisation to predict responses in the form of flow and pollutant concentration
For a copy of SWMM, click
Hydrological Simulation Program - FORTRAN (HSPF;
Johanson et al., 1984; Donigian et al., 1984) is a comprehensive package for simulation of
watershed hydrology and water quality for both conventional and toxic organic pollutants.
HSPF integrates the watershed-scale ARM and NPS models into a basin-scale analysis
framework that includes fate and transport in one-dimensional stream channels. It is the
only comprehensive model of watershed hydrology and water quality that allows the
integrated simulation of land and soil contaminant runoff processes with in-stream
hydraulic and sediment-chemical Interactions.
The result of this simulation is a time history of the runoff flow rate, sediment load,
and nutrient and pesticide concentrations, along with a time history of water quantity and
quality at any point in a watershed.
HSPF simulates three sediment types (sand, silt, and clay) in addition to a single
organic chemical and transformation products of that chemical. The transfer and reaction
processes included are hydrolysis, oxidation, photolysis, biodegradation, volatilization,
and sorption. Sorption is modelled as a first-order kinetic process in which the user must
specify a desorption rate and an equilibrium partition coefficient for each of the three
solids types. Resuspension and settling of silts and clays (cohesive solids) are defined
in terms of shear stress at the sediment water interface. The capacity of the system to
transport sand at a particular flow is calculated and re-suspension or settling is defined
by the difference between the sand in suspension and the transport capacity. Calibration
of the model requires data for each of the three solids types. Benthic exchange is
modelled as sorption/desorption and deposition/scour with surficial benthic sediments.
Underlying sediment and pore water are not modelled.
Data needs for HSPF can be extensive. HSPF is a continuous simulation program and
requires continuous data to drive the simulations. As a minimum, continuous rainfall
records are required to drive the runoff model and additional records of
evapotranspiration, temperature, and solar intensity are desirable. A large number of
model parameters can be specified although default values are provided where reasonable
values are available. HSPF is a general-purpose program and special attention has been
paid to cases where input parameters are omitted. Option flags allow bypassing of whole
sections of the program where data are not available.
HSPF produces a time history of the runoff flow rate, sediment load, and nutrient and
pesticide concentrations, along with a time history of water quantity and quality at any
point In a watershed. Simulation results can be processed through a frequency and duration
analysis routine that produces output compatible with conventional toxicological measures
(e.g., 96-hour LC50).
Limitations of HSPF include the assumption that the 'Stanford Watershed Model" is
appropriate for the area being modelled. Further, the in-stream model assumes that the
receiving water body is well-mixed with width and depth and is thus limited to well-mixed
rivers and reservoirs. Application of this methodology generally requires a team effort
because of its comprehensive nature.
HSPF and the earlier models from which it was developed have been extensively applied
in a wide variety of hydrologic and water quality studies (Barnwell and Johanson, 1981;
Barnwell and Kittle, 1984) including pesticide runoff model testing (Lorber and Mulkey,
1981), aquatic fate and transport model testing (Mulkey et al., 1986; Schnoor et al.,
1987), analyses of agricultural best management practices (Donigian et al., 1983; Bicknell
et al., 1984) and as part of pesticide exposure assessments in surface waters. An
application of HSPF in a screening methodology for pesticide review is described by
Donigian et al. (1986). The Stream Transport and Agricultural Runoff for Exposure
Assessment Methodology (STREAM) applies the HSPF program to various test watersheds for
five major crops in four agricultural regions in the United States, defines a
'representative' watershed based on regional conditions and an extrapolation of the
calibration for the test watershed, and performs a sensitivity analysis on key pesticide
parameters to generate cumulative frequency distributions of pesticide loads and
concentrations in each region. The resulting methodology requires the user to evaluate
only the crops and regions of interest, the pesticide application rate, and three
pesticide parameters - the partition coefficient, the sediment decay rate, and the
solution decay rate.
For a copy of HSPF, click
The Enhanced Stream Water Quality Model QUAL2E
and QUAL2EUNCAS (Brown and Barnwell, 1987) permits simulation of several water quality
constituents in a branching stream system using a finite difference solution to the
one-dimensional advective-dispersive mass transport and reaction equation. The conceptual
representation of a stream used in the QUAL2E formulation is a stream reach that has been
divided into a number of subreaches or computational elements equivalent to finite
differences. For each computational element, a hydrologic balance in terms of flow (Q), a
heat balance in terms of temperature (T). and a materials balance in terms of
concentration (C) is written. Both advective and dispersive transport are considered in
the materials balance. Mass can be gained or lost from the element by transport processes,
external sources and sinks (e.g., waste discharges or withdrawals) or by internal sources
and sinks (e.g., benthic sources or biological transformations).
The equation is solved for the steady-flow, steady state condition in a classical
implicit backward difference method. The specific equations and solution technique are
described in detail in the QUAL2E computer program documentation.
The QUAL series of computer programs has a long history in water quality management.
The foundation upon which the series is built was laid by the Texas Water Development
Board (TWDB) in the late 1960s. In the early 1970s, EPA began a program to provide water
quality models for major river basins and specified that QUAL-I be used as the basis for
developing new, more advanced, basin-specific models. Many versions of the QUAL-II model
emerged from this effort. One in particular was further improved in the mid- 1970s for the
Southeast Michigan Council of Governments (SEMCOG), the area-wide wastewater planning
agency for the Detroit metropolitan area. Because of its flexibility and thorough
documentation, the SEMCOG version of QUAL-II, known as QUAL-11/ SEMCOG received widespread
use, especially in wasteload allocation studies. In the late 1970's, the National Council
of the Paper Industry for Air and Stream Improvement (NCASI) undertook a thorough review,
testing and documentation project covering a variety of water quality models, including
QUAL-II/SEMCOG. Changes resulting from this review were incorporated in the program and
the model was renamed QUAL-II/NCASI. NCASI and other groups, such as the U. S. Geological
Survey (USGS) tested the revised program on several intensively sampled rivers across the
United States. Recently, the model has seen several European applications in England,
Greece, Belgium and Spain. Other applications of QUAL-II range from South America to the
Far East, including South Korea, the People's Republic of China, and Thailand. A number of
applications and ongoing work with the QUAL2E model are described by Barnwell, Brown and
Prototype representation in QUAL2E consists of dividing a stream into a network of
"Headwaters', "Reaches', and 'Junctions.' The fundamental reason for subdividing
sections of stream into 'Reaches" is that QUAL2E assumes that some 26 physical,
chemical and biological properties (model input parameters or coefficients) are constant
along a "Reach.' The question that must be addressed in order to define a
"Reach' is what constitutes "significant' change in these model inputs -
'significant' in the sense of their impact on simulation results, not necessarily in the
sense of change in the inputs themselves.
Mass transport in the QUAL2E computer program is handled in a relatively simple manner.
There seems to be some confusion about QUAL2E's transport capabilities as it is sometimes
called a "dynamic' model. However, in all of the computer programs in the QUAL
series, there is an explicit assumption of steady flow; the only time-varying forcing
functions are the climatologic variables that primarily affect temperature and algal
growth. A more proper term for this capability is diurnal, indicating variation over a
24-hour period. The forcing function used for estimating transport is the streamflow rate,
which, as mentioned above, is assumed to be constant. Stream velocity, cross-sectional
area, and depth are computed from streamflow.
One of the most important considerations in determining the assimilative capacity of a
stream is Its ability to maintain an adequate dissolved oxygen concentration. The QUAL2E
computer program includes the major interactions of the nutrient cycles, algal production,
benthic and carbonaceous oxygen demand, atmospheric reaeration, and their effect on the
dissolved oxygen balance In addition, the computer program includes a heat balance for the
computation of temperature and mass balances for conservative minerals, coliform bacteria,
and nonconservative constituents such as radioactive substances. Chlorophyll 'a' is
modelled as the indicator of planktonic algae biomass in QUAL2E.
The nitrogen cycle is composed of four compartments: Organic nitrogen, Ammonia
nitrogen, Nitrite nitrogen, and Nitrate nitrogen. The phosphorus cycle is similar to, but
simpler than, the nitrogen cycle, having only two compartments. Ultimate carbonaceous
biochemical oxygen demand (BOD) is modelled as a first-order degradation process in
QUAL2E, which also takes into account removal by settling and does not affect the oxygen
balance. QUAL2E will convert the traditional 5-day BOD values to ultimate BOD for internal
calculations. The processes discussed above represent the primary Internal sinks of
dissolved oxygen in the QUAL2E computer program. The major source of dissolved oxygen, in
addition to that supplied from algal photosynthesis, is atmospheric reaeration.
An uncertainty analysis is available in QUAL2EUNCAS. A major problem faced by the user
when working with a complex model such as QUAL2E is model calibration and determination of
the most efficient plan for collection of calibration data. This problem can be addressed
by application of principles of uncertainty analysis. These strategies have been applied
to QUAL2E and the resulting computer program is named QUAL2E-UNCAS. Three uncertainty
analysis techniques are employed in QUAL2E-UNCAS: sensitivity analysis, first order error
analysis, and monte carlo simulation. The computer program uses pre- and post-processing
algorithms to select the input variables and/or parameters to be altered without the user
having to manually restructure the input data set and to store and manipulate only the
output of Interest. The modeler is free to select the important variables and locations in
the stream network where uncertainty effects are desired.
QUAL2E requires some degree of modeling sophistication and expertise on the part of a
user. The user must supply more than 100 individual inputs, some of which require
considerable judgement to estimate. The uncertainty analysis procedures incorporated in
the computer program serve both to guide the user in the calibration process as well as to
provide information about the uncertainty associated with calibrated model.
For a copy of QUAL2E, click
Water Quality Analysis Simulation Program, WASP
(Ambrose et al., 1987) is a generalized framework for modeling contaminant fate and
transport in surface waters. WASP5 is the latest of a series of WASP programs (DI Toro et
al., 1983; Ambrose, et al., 1983; Connolly and Winfield, 1984, Ambrose et al., 1986).
Based on the flexible compartment modeling approach, WASP can be applied in one, two, or
three dimensions. WASP is designed to permit easy substitution of user-written routines
into the program structure. Problems that have been studied using the WASP framework
include biochemical oxygen demand and dissolved oxygen dynamics, nutrients and
eutrophication, bacterial contamination, and organic chemical and heavy metal
Two WASP models are provided: the toxics WASP model, TOXI, combines a kinetic structure
adapted from EXAMS2 (Burns and Cline, 1985) with the WASP transport structure and simple
sediment balance algorithms to predict dissolved and sorbed chemical concentrations in the
bed and overlying waters. The dissolved oxygen/ eutrophication WASP model EUTRO combines a
kinetic structure adapted from the Potomac Eutrophication Model (Thomann and Fitzpatrick,
1982) with the WASP transport structure to predict DO and phytoplankton dynamics affected
by nutrients and organic material.
WASP input and output linkages also have been provided to other stand-alone models.
Flows and volumes predicted by the link-node hydrodynamic model DYNHYD can be read and
used by WASP. Loading files from PRZM and HSPF can be reformatted and read by WASP.
Toxicant concentrations predicted by TOXI can be read and used by both the WASP Food Chain
Model and the fish bioaccumulation model FGETS.
A body of water is represented in WASP as a series of computational elements or
segments. Environmental properties and chemical concentrations are modelled as spatially
constant within segments. Segment volumes and type (surface water, subsurface water,
surface benthic, subsurface benthic) must be specified, along with hydraulic coefficients
for riverine networks.
Structurally, the WASP program includes six mechanisms for describing transport. These
'transport fields' consist of advection and dispersion in the water column; advection and
dispersion in the pore water; settling, re-suspension, and sedimentation of up to three
classes of solids; and evaporation or precipitation. To describe advection within WASP,
each inflow or circulation pattern requires specification of the fraction routed through
relevant water column segments and the time history of the corresponding flow. Dispersion
requires specification of cross-sectional areas between model segments, characteristic
mixing lengths, and the time history of the corresponding dispersion coefficient. For each
state variable (termed 'system' In WASP), the user must specify loads, boundary
concentrations, and initial concentrations. The dissolved fractions of each variable also
must be specified for each segment. Only dissolved concentrations are transported by pore
water and only particulate concentrations are transported by solids.
Each variable is advected and dispersed among water segments, and exchanged with
surficial benthic segments by diffusive mixing. Sorbed or particulate fractions may settle
through water column segments and deposit to or erode from surficial benthic segments.
Within the bed, dissolved variables may migrate downward or upward through percolation and
pore water diffusion. Sorbed variables may migrate downward or upward through net
sedimentation or erosion.
For a copy of WASP, click
The Source Loading and Management Model (SLAMM)
was developed to assist water and land resources planners in evaluating the effects of
alternative control practices and development characteristics on urban runoff quality and
quantity. SLAMM only evaluates runoff characteristics at the source areas In the watershed
and at the discharge outfall; it does not directly evaluate receiving water responses.
However, earlier versions of SLAMM have been used in conjunction with receiving water
models (HSPF) to examine the ultimate effects of urban runoff (Ontario Ministry of the
SLAMM is different from other urban runoff models. Beside examining land development
practices and many source area and outfall control practices, it contains two major areas
of improvements. These are corrected algorithms for the washoff of street dirt and the
incorporation of small storm hydrology. Without these corrections, it is not possible to
appropriately predict the outfall responses associated with source area controls and
SLAMM continually develops mass balances for both particulate and dissolved pollutants
and runoff flow volumes for different development and rain characteristics. It was
designed to give relatively simple answers (pollutant mass discharges and control measure
costs for a very large variety of potential conditions). It is therefore used as a
planning tool, such as to generate information needed to make planning level decisions,
while not generating superfluous information unnecessary for these planning decisions. It
is recognized that many stormwater models are available that can generate predicted
outfall conditions with great resolution, but this information is of little value to
planners and substantially increases the data 'gathering and computational costs.
SLAMM predicts urban runoff discharge parameters (total storm runoff flow volume,
flow-weighted pollutant concentrations, and total storm pollutant yields) for many
individual storms and for the study period. It does not predict these parameters for
periods within individual storms. Stormwater management decisions are most appropriately
based on long-term conditions and not on rapidly varying conditions. As examples,
stormwater effects are mostly associated with the long-term discharges of pollutants that
accumulate in the receiving water sediments (Pitt and Bozeman 1982) or in increased flows
that destroy habitats and increase channel erosion (Pitt and Bissonnette 1984).
Very few studies investigating problems in urban runoff receiving waters have found
significant urban runoff quality effects associated with individual events (Heaney et al.
1980). Water quality standards (especially for heavy metals and bacteria) may be violated
during most rains at outfalls, but the durations of the violations are usually short and
only occur for small percentages of the year (EPA 1983). A model capable of accurately
estimating rapidly changing conditions within an individual storm would be very large and
require greater knowledge than is currently available. SLAMM was developed to supply the
type of information most needed to make management decisions, balanced against current
urban runoff knowledge, costs of obtaining program Input Information, and costs of running
the program. If receiving water response information is also needed, the output from SLAMM
can be used in specific receiving water models for the pollutants of concern.
SLAMM was conceived in the mid 1970s mostly as a data reduction tool for use In early
street cleaning projects (Pitt 1979). Special field studies were designed and conducted in
conjunction with many separate field projects to obtain necessary Information (mostly
source area sheetflow characterization and control measure performance information). After
substantial work with the initial versions of the 'model", It was decided that a
needed management tool (at the decision making or planning level) could be developed.
SLAMM was therefore expanded to enable other management practices (located at source areas
and at the outfall) to be evaluated. A preliminary description of SLAMM was included in
the Castro Valley Nationwide Urban Runofr Program (NURP) report (Pitt and Shawley 1982),
but it was not until the other NURP projects and recent field studies conducted by Pitt
(1987) were completed that a more comprehensive version of the model could to be finished
SLAMM requires information concerning the urban runoff controls to be evaluated and the
development characteristics of the study area. SLAMM can evaluate the effects of a number
of different stormwater control practices on runoff quality and quantity, including:
- wet detention basins
- porous pavement
- infiltration devices
- street cleaning
- catchbasin cleaning
- grass swales
- roof runoff disconnections
- paved parking and storage area runoff disconnections
The modeling procedures used to evaluate these stormwater controls are based on many
past research projects (Pitt 1985 and 1987). However, if improperly designed, constructed,
or maintained, the controls could have little benefit. SLAMM requires specific information
concerning each practice to be evaluated. As an example, grass swale evaluations require
the effective infiltration rate in the swale, the drainage density, and the swale width.
Wet detention basin evaluations require information concerning the area and
cross-sectional shape of the basin and the sizes and types of outlet structures. There are
also many development features of an area that affect runoff and that must be known,
- areas of each source type in the watershed
- effective SCS soil type
- building density
- land use
- presence of alleys
- roof pitch
- pavement texture
- traffic density
Of these features, the areas of the separate sources (such as roof area, street area,
landscaped area, etc.) are the most important and should be obtained from aerial
photographs. Building density, land use, and alley information can also be obtained from
aerial photographs. SCS native soil types can be obtained from soil maps, but native soils
have little hydraulic resemblance to typically highly disturbed and compacted urban soils.
Specific infiltration tests should therefore be conducted in an area to obtain an estimate
of the actual hydraulic responses of the urban soils of interest.
Inventory surveys of the neighbourhoods to be evaluated should be conducted to
determine roof and paved area connections and the type of drainage system. Other site
information that can be obtained from site surveys include roof pitches, pavement
textures, and traffic densities. If the model is to be used for future developments, these
characteristics can be estimated from current developments or from the site plans.
Rain information for the period of study is also needed. Because SLAMM only evaluates
complete storm conditions, detailed rain data is not needed. Only rain start and end dates
(and times) and total rain depths are needed for each event. Typically, study periods
containing 10 to 100 rains are used in each evaluation. SLAMM currently does not evaluate
snowmelt or baseflow conditions. Like any urban runoff model, SLAMM must also be
calibrated and verified for local conditions. Needed calibration files describe the runoff
responses and the sheetflow runoff qualities for the different source areas.
The principal outputs are statistical information on quantity and quality of runoff
(and overflow in combined drainage and sewerage systems which are common in US cities) and
pollutographs for selected individual events.
Cornell Mixing Zone Expert System (CORMIX) can
be used for the analysis, computation, design of aqueous toxic or conventional pollutant
discharges into diverse waterbodies. Major emphasis is on computation of plume geometry
and dilution characteristics within a receiving water's initial mixing zone so that
compliance with regulatory constraints can be judged. It also computes discharge plume
behavior at larger distances.
CORMIX, Version 2.10, combines:
CORMIX1 - for submerged single point discharges;
CORMIX2 - for submerged multiport diffuser discharges; and
CORMIX3 - for buoyant surface discharges,
into a single comprehensive system for modeling diverse types of aquatic pollutant
discharge into all types of receiving water bodies streams, rivers, lakes, reservoirs,
estuaries, coastal waters). Version 2.10 also includes a FAST-CORMIX option that provides
fast data entry mode for experienced users.
Notes from CEAM-USERS Digest 133:
The person responsible (as at 970701) for distribution of CORMIX is
DAVE DISNEY [DISNEY.DAVE@EPAMAIL.EPA.GOV]
Center for Exposure Assessment Modeling (CEAM)
U.S. Environmental Protection Agency (U.S. EPA)
Office of Research and Development (ORD)
National Exposure Research Laboratory - Ecosystems Research Division
960 College Station Road
Athens, Georgia (GA) 30605-2700 USA
Users can send questions and/or requests for technical assistance to the CEAM address.
The user list for announcements is: CEAM-USERS@valley.rtpnc.epa.gov
Release of CORMIX Technical Report (June 1997)
The Oregon Graduate Institute--the technical support center for CORMIX users--through the
U.S. EPA Center for Exposure Assessment Modeling (CEAM) announces the availability of the
technical report titled "CORMIX3: An Expert System for Mixing Zone Analysis and
Prediction of Buoyant Surface Discharges" by Gilbert R. Jones, Jonathan D. Nash, and
Gerhard H.Jirka. This report, by the DeFrees Hydraulics Laboratory of Cornell University,
documents the technical background of CORMIX3. The report is available as both an Adobe
Acrobat 3.0 (pdf) and Postscript file at Uniform Resource Locator (URL):
Users can down load the documentation free of charge after completing a short registration
form. For questions, information, and technical support concerning CORMIX model and/or
program content, application, and/or theory, contact Dr. Robert Doneker for assistance
Department of Environmental Science and Engineering
Oregon Graduate Institute
P.O. Box 91000
Portland, OR 97291-1000
Telephone: Voice: 503/690-4053
For a copy of CORMIX and its documentation, click here
EPANET is a computer program that performs
extended period simulation of hydraulic and water quality behavior within pressurized pipe
networks. A network can consist of pipes, nodes (pipe junctions), pumps, valves and
storage tanks or reservoirs. EPANET tracks the flow of water in each pipe, the pressure at
each node, the height of water in each tank, and the concentration of a substance
throughout the network during a multi-time period simulation. In addition to substance
concentrations, water age and source tracing can also be simulated.
EPANET is designed to be a tool for improving our understanding of the movement and
fate of drinking water constituents within distribution systems. The water quality module
of EPANET is equipped to model such phenomena as reactions within the bulk flow, reactions
at the pipe wall, and mass transport between the bulk flow and pipe wall. As we gain more
experience and knowledge of water quality behavior within distribution systems we intend
to update and refine EPANET to reflect this progress.
Another feature of EPANET is its coordinated approach to modeling network hydraulics
and water quality. The program can compute a simultaneous solution for both conditions
together. Alternatively it can compute only network hydraulics and save these results to a
file, or use a previously saved hydraulics file to drive a water quality simulation.
The water quality module of EPANET can track the growth or decay of a substance by
reaction as it travels through a distribution system. Reaction can occur both within the
bulk flow and with material along the pipe wall. Bulk fluid reactions can also occur
within tanks. EPANET models both types of reactions using first order kinetics. The bulk
reaction is defined through a bulk reaction rate constant (Kb) while a wall reaction rate
constant (Kw) is associated with the wall reaction. Different values for Kb can be used
for different pipes and tanks in the network and the same holds true for Kw. Kb has units
of 1/days while Kw has units of ft/day (or m/day). These coefficients are positive for
growth reactions and negative for decay reactions.
EPANET views a water distribution network as a collection of links connected together
at their endpoints called nodes. Links and nodes are identified with ID numbers and can be
arranged in any fashion.
EPANET can be used for many different kinds of applications in distribution system
analysis. Sampling program design, hydraulic model calibration, chlorine residual
analysis, and consumer exposure assessment are some examples. EPANET can help assess
alternative management strategies for improving water quality throughout a system. These
- altering source utilization within multiple source systems,
- altering pumping and tank filling/emptying schedules,
- use of satellite treatment, such as re-chlorination at storage tanks,
- targeted pipe cleaning and replacement.
The EPANET package contains two program modules. One is a network simulator that runs
under DOS, receiving its input from a file and writing its output to another file. The
user must use external programs to edit the input file and view or print the output file.
(An optional DOS shell program is provided that interactively edits EPANET input, runs the
simulator, and views or prints its output according to selections made from a menu). The
second module is a program that allows one to edit EPANET input data, run the simulator,
and graphically display its results in a variety of ways on a map of the network. Thus
there are two different ways to run EPANET -- under DOS or under Windows. We believe that
for most situations the visualization power of the Windows version is an essential aid in
trying to comprehend the results of running EPANET and recommend that this mode be used if
your computer hardware and software can support it.
This Windows version of 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. These include color-coded network maps, data tables, and time series