Following
is a list of freeware that provides tools for modeling groundwater flow and contaminant fate and transport. Before you access any software or apps, please read our disclaimer and
permissions page if you haven't already done so.
2DFATMIC Source Code (for UNIX)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. FATMIC 2D (2DFATMIC) simulates subsurface flow, transport, and fate of contaminants which are undergoing chemical and/or biological transformations. The model is applicable to transient conditions in both saturated and unsaturated zones. The flow module is a Galerkin finite element solution of Richard's equation. The transport module is a hybrid LagrangianEulerian approach with an adapted zooming and peak capturing algorithm. This model can almost eliminate spurious oscillation, numerical dispersion, and peak clipping due to advective transport.
3DFATMIC (for UNIX)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. FATMIC 3D (3DFATMIC) simulates subsurface flow, transport, and fate of contaminants which are undergoing chemical and/or biological transformations. The model is applicable to transient conditions in both saturated and unsaturated zones. The flow module is a Galerkin finite element solution of Richard's equation. The transport module is a hybrid LagrangianEulerian approach with an adapted zooming and peak capturing algorithm. This model can almost eliminate spurious oscillation, numerical dispersion, and peak clipping due to advective transport.
AGU10
By Integrated GroundWater Modeling Center (IGWMC). A collection of screening level analytical flow and transport programs for homogeneous, isotropic flow fields, based on the American Geophysical Union's Water Resources Monograph 10. It consists of five simulation programs in FORTRAN and two pre/postprocessors in Microsoft BASIC.
ANALGWST (for Data General AViiON)
By US Geological Survey (USGS). A set of programs that calculate analytical solutions for one, two, and threedimensional solute transport in groundwater systems with uniform flow. UNIX source code is available.
ANNIE (for DOS)
By US Geological Survey (USGS). Designed to help users interactively store, retrieve, list, plot, check, and update spatial, parametric, and timeseries data for hydrologic models and analyses. Data are stored in a direct access file called a Watershed Data Management (WDM) file.
ANNIE (for Solaris)
By US Geological Survey (USGS). Designed to help users interactively store, retrieve, list, plot, check, and update spatial, parametric, and timeseries data for hydrologic models and analyses. Data are stored in a direct access file called a Watershed Data Management (WDM) file. UNIX source code is available.
AT123DAT
By Integrated GroundWater Modeling Center (IGWMC). AT123D is based on an analytical solution for transient one, two, or threedimensional transport of a dissolved chemical or radionuclide or heat in a homogeneous aquifer with uniform, stationary regional flow.
BIOCHLOR
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. BIOCHLOR is a screening model that simulates remediation by natural attenuation of dissolved solvents at chlorinated solvent release sites. BIOCHLOR can be used to simulate solute transport without decay and solute transport with biodegredation modeled as a sequential firstorder process within one or two different reaction zones. Runs Microsoft Excel 97 or Excel 2000.
BIOMOC (for Data General AViiON)
By US Geological Survey (USGS). A twodimensional model that can simulate the transport and biotransformation of multiple reacting solutes. UNIX source code is available.
BIOMOC (for DOS)
By US Geological Survey (USGS). A twodimensional model that can simulate the transport and biotransformation of multiple reacting solutes. Source code is available.
BIOMOC (for Silicon Graphics Indigo)
By US Geological Survey (USGS). A twodimensional model that can simulate the transport and biotransformation of multiple reacting solutes. UNIX source code is available.
BIOMOC (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). A twodimensional model that can simulate the transport and biotransformation of multiple reacting solutes. UNIX source code is available.
BIOMOC (for Windows 2000)
By US Geological Survey (USGS). A twodimensional model that can simulate the transport and biotransformation of multiple reacting solutes. Source code is available.
BIOPLUME II (for DOS)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. BIOPLUME II is a simulation that computes concentrations of dissolved hydrocarbon under the influence of oxygenlimited biodegradation in an aquifer. The model solves the solute transport equation for both hydrocarbon and oxygen, assumes an instantaneous reaction between oxygen and hydrocarbon, and combines the two plumes using the principle of superposition. Computations account for convection, dispersion, mixing, and biodegradation effects.
BIOPLUME III
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. BIOPLUME III is a 2D, finite difference model for simulating the natural attenuation of organic contaminants in groundwater due to the processes of advection, dispersion, sorption, and biodegradation.
BIOSCREEN
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. BIOSCREEN is a screening model which simulates remediation through natural attenuation of dissolved hydrocarbons at petroleum fuel release sites. The software, programmed in the Microsoft Excel spreadsheet environment and based on the Domenico analytical solute transport model, has the ability to simulate advection, dispersion, adsorption, and aerobic decay as well as anaerobic reactions that have been shown to be the dominant biodegradation processes at many petroleum release sites. Runs on Windows 95/98.
CONTOUR (for Data General AViiON)
By US Geological Survey (USGS). A contouring program for gridded data designed for use with finitedifference models such as MODFLOW. UNIX source code is available.
CONTOUR (for Silicon Graphics Indigo)
By US Geological Survey (USGS). A contouring program for gridded data designed for use with finitedifference models such as MODFLOW. UNIX source code is available.
CONTOUR (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). A contouring program for gridded data designed for use with finitedifference models such as MODFLOW. UNIX source code is available.
CSMoS Online Model Information Database
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory and International Ground Water Modeling Center. Search for information on modeling software by keyword, software name, distributor, or author. Note: Last modification date for database was 1998.
Darcy Flux & Groundwater Velocity Calculator
By GroundwaterSoftware.com. A free, online tool to calculate Darcy's Law and average groundwater velocity.
GFLOW (Educational Version)
By Haitjema Software. GFLOW is a stepwise groundwater flow model based on the analytic element method. It models steady state flow in a single heterogeneous aquifer using the DupuitForchheimer assumption. While GFLOW supports some local transient and threedimensional flow modeling, it is particularly suitable for modeling regional horizontal flow. [Only the educational version is free.]
Groundwater Modeling System (GMS)
By US Army Corps of Engineers. The GMS provides an integrated computational environment for simulating subsurface flow, contaminant fate/transport, and the efficacy and design of remediation systems.
HSSM (for DOS)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. HSSM simulates flow of the LNAPL phase and transport of a chemical constituent of the LNAPL from the surface to the water table; radial spreading of the LNAPL phase at the water table, and dissolution and aquifer transport of the chemical constituent.
HSSM (Hydrocarbon Spill Screening Model)  Windows
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. HSSM simulates flow of the LNAPL phase and transport of a chemical constituent of the LNAPL from the surface to the water table; radial spreading of the LNAPL phase at the water table, and dissolution and aquifer transport of the chemical constituent.
HSSM  Modelo de evaluación de derrames de hidrocarburos (en Espanol)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. Simula el flujo de la fase LNAPL (líquidos livianos en fase no acuosa) y el transporte de un componente químico por estos líquidos desde la superficie hasta las napas freáticas; la difusión de la fase LNAPL en la napa freática; y la disolución y el transporte acuífero del componente químico.
HST3D (for Linux)
By US Geological Survey (USGS). The Heat and SoluteTransport Program (HST3D) simulates groundwater flow and associated heat and solute transport in three dimensions. The HST3D program may be used for analysis of problems such as those related to subsurfacewaste injection, landfill leaching, saltwater intrusion, freshwater recharge and recovery, radioactivewaste disposal, hotwater geothermal systems, and subsurfaceenergy storage.
HST3D (for UNIX)
By US Geological Survey (USGS). The Heat and SoluteTransport Program (HST3D) simulates groundwater flow and associated heat and solute transport in three dimensions. The HST3D program may be used for analysis of problems such as those related to subsurfacewaste injection, landfill leaching, saltwater intrusion, freshwater recharge and recovery, radioactivewaste disposal, hotwater geothermal systems, and subsurfaceenergy storage.
HST3D (for Windows)
By US Geological Survey (USGS). The Heat and SoluteTransport Program (HST3D) simulates groundwater flow and associated heat and solute transport in three dimensions. The HST3D program may be used for analysis of problems such as those related to subsurfacewaste injection, landfill leaching, saltwater intrusion, freshwater recharge and recovery, radioactivewaste disposal, hotwater geothermal systems, and subsurfaceenergy storage.
HydroOffice
By Michal Truban. The HydroOffice package is modular software package for users interested in water sciences. It was created and is currently being developed mainly in the author's free time. Its aim is to create powerful software tools to streamline the work in the water sciences. The beginnings of the HydroOffice modules development dates back to 2002 and the individual modules are progressively developed and new modules are added.
HYDROTHERM (for Linux)
By US Geological Survey (USGS). A threedimensional finitedifference model to simulate multiphase groundwater flow and heat transport in the temperature range of 0 to 1,200 degrees Celsius. UNIX source code is available.
HYDROTHERM (for Windows)
By US Geological Survey (USGS). A threedimensional finitedifference model to simulate multiphase groundwater flow and heat transport in the temperature range of 0 to 1,200 degrees Celsius.
Internet Geographical Exposure Modeling System (IGEMS)
By US Environmental Protection Agency, Office of Pollution Prevention and Toxics (OPPT). IGEMS is a modernization of OPPT's older Graphical Exposure Modeling System and PCGEMS tools. IGEMS brings together in one system several EPA environmental fate and transport models and some of the environmental data needed to run them. IGEMS includes models and data for ambient air, surface water, soil, and ground water, and makes the models much easier to use than their standalone counterparts. IGEMS will have graphics and Geographical Information System (GIS) capabilities for displaying environmental modeling results.
Linear Interpolation Calculator
By GroundwaterSoftware.com. A free, online tool to perform linear interpolation calculations. Linear interpolation determines, from two points (x1,y1) and (x2,y2), what the value of y is at a different point x3.
Lizza  PAKP
By Institute for Water Resources (Jaroslav Cerni) and Bioengineering Research and Development Center  BioIRC. LizzaPAKP is a groundwater flow simulation system which consists of solver based on finite element method (PAKP) and user interface (Lizza). It provides full 3D modeling capabilities, stationary and nonstationary modeling, saturated and nonsaturated environment calculation, as well as mass and heat transport handling. PAKP module incorporates a solver based on MPI paradigm, making its presence a grid site requirement.
MFI (for Data General AViiON)
By US Geological Survey (USGS). A data input program for USGS's models MODFLOW, MODPATH, and MOC3D. Source code is available.
MFI (for DOS)
By US Geological Survey (USGS). A data input program for USGS's models MODFLOW, MODPATH, and MOC3D. Source code is available.
MMSOILS (for DOS)
By US Environmental Protection Agency, Center for Exposure Assessment Modeling (CEAM). The Multimedia Contaminant Fate, Transport, and Exposure Model (MMSOILS) estimates the human exposure and health risk associated with releases of contamination from hazardous waste sites. The methodology consists of a multimedia model that addresses the transport of a chemical in groundwater, surface water, soil erosion, the atmosphere, and accumulation in the foodchain. The human exposure pathways considered in the methodology include: soil ingestion, air inhalation of volatiles and particulates, dermal contact, ingestion of drinking water, consumption of fish, consumption of plants grown in contaminated soil, and consumption of animals grazing on contaminated pasture.
MOC (for Data General AViiON)
By US Geological Survey (USGS). Twodimensional methodofcharacteristics groundwater flow and transport model. It simulates solute transport in flowing ground water and is applicable to one or twodimensional problems involving steadystate or transient flow. Source code is available.
MOC (for DOS)
By US Geological Survey (USGS). Twodimensional methodofcharacteristics groundwater flow and transport model. It simulates solute transport in flowing ground water and is applicable to one or twodimensional problems involving steadystate or transient flow. Source code is available.
MOC (for Macintosh)
By US Geological Survey (USGS). Twodimensional methodofcharacteristics groundwater flow and transport model. It simulates solute transport in flowing ground water and is applicable to one or twodimensional problems involving steadystate or transient flow. Includes source code.
MOC (for Silicon Graphics Indigo)
By US Geological Survey (USGS). Twodimensional methodofcharacteristics groundwater flow and transport model. It simulates solute transport in flowing ground water and is applicable to one or twodimensional problems involving steadystate or transient flow. Source code is available.
MOC (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). Twodimensional methodofcharacteristics groundwater flow and transport model. It simulates solute transport in flowing ground water and is applicable to one or twodimensional problems involving steadystate or transient flow. Source code is available.
MOC3D (for DOS)
By US Geological Survey (USGS). A threedimensional methodofcharacteristics groundwater flow and transport model. Source code is available.
MOC3D (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). A threedimensional methodofcharacteristics groundwater flow and transport model. Source code is available.
MOCDENSE (for Data General AViiON)
By US Geological Survey (USGS). A twoconstituent solute transport model for ground water having variable density. Source code is available.
MOCDENSE (for DOS)
By US Geological Survey (USGS). A twoconstituent solute transport model for ground water having variable density. Source code is available.
MOCDENSE (for Silicon Graphics Indigo)
By US Geological Survey (USGS). A twoconstituent solute transport model for ground water having variable density. Source code is available.
MOCDENSE (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). A twoconstituent solute transport model for ground water having variable density. Source code is available.
MODBRNCH (for Data General AViiON)
By US Geological Survey (USGS). Surface and groundwater interactions can be simulated by the coupled BRANCH and USGS modular, threedimensional, finitedifference groundwater flow (MODFLOW96) models, referred to as MODBRNCH. Source code is available.
MODBRNCH (for DOS)
By US Geological Survey (USGS). Surface and groundwater interactions can be simulated by the coupled BRANCH and USGS modular, threedimensional, finitedifference groundwater flow (MODFLOW96) models, referred to as MODBRNCH. Source code is available.
MODBRNCH (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). Surface and groundwater interactions can be simulated by the coupled BRANCH and USGS modular, threedimensional, finitedifference groundwater flow (MODFLOW96) models, referred to as MODBRNCH. Source code is available.
MODFE (for Data General AViiOM)
By US Geological Survey (USGS). A modular finiteelement model for areal and axisymmetric groundwater flow problems. Source code is available.
MODFE (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). A modular finiteelement model for areal and axisymmetric groundwater flow problems. Source code is available.
MODFLOW2000 (for UNIX)
By US Geological Survey (USGS). MODFLOW2000 simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined. Flow from external stresses, such as flow to wells, areal recharge, evapotranspiration, flow to drains, and flow through river beds, can be simulated. Hydraulic conductivities or transmissivities for any layer may differ spatially and be anisotropic (restricted to having the principal directions aligned with the grid axes), and the storage coefficient may be heterogeneous. Specified head and specified flux boundaries can be simulated as can a head dependent flux across the model's outer boundary that allows water to be supplied to a boundary block in the modeled area at a rate proportional to the current head difference between a "source" of water outside the modeled area and the boundary block. MODFLOW is currently the most used numerical model in the U.S. Geological Survey for groundwater flow problems. In addition to simulating groundwater flow, the scope of MODFLOW2000 has been expanded to incorporate related capabilities such as solute transport and parameter estimation.
MODFLOW2000 (for Windows)
By US Geological Survey (USGS). MODFLOW2000 simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined. Flow from external stresses, such as flow to wells, areal recharge, evapotranspiration, flow to drains, and flow through river beds, can be simulated. Hydraulic conductivities or transmissivities for any layer may differ spatially and be anisotropic (restricted to having the principal directions aligned with the grid axes), and the storage coefficient may be heterogeneous. Specified head and specified flux boundaries can be simulated as can a head dependent flux across the model's outer boundary that allows water to be supplied to a boundary block in the modeled area at a rate proportional to the current head difference between a "source" of water outside the modeled area and the boundary block. MODFLOW is currently the most used numerical model in the U.S. Geological Survey for groundwater flow problems. In addition to simulating groundwater flow, the scope of MODFLOW2000 has been expanded to incorporate related capabilities such as solute transport and parameter estimation.
MODFLOW2005
By US Geological Survey (USGS). MODFLOW2005 can be used to help address such issues as water availability and sustainability, interaction of ground water and surface water, wellhead protection, seawater intrusion, and remediation of contaminated ground water.
MODFLOW88 (for Data General AViiON)
By US Geological Survey (USGS). The original modular finitedifference groundwater flow model (MODFLOW) simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined (McDonald and Harbaugh, 1988). An easier to use version MODFLOW96 is also available. Source code is available.
MODFLOW88 (for DOS)
By US Geological Survey (USGS). The original modular finitedifference groundwater flow model (MODFLOW) simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined (McDonald and Harbaugh, 1988). An easier to use version MODFLOW96 is also available. Source code is available.
MODFLOW88 (for Silicon Graphics Indigo)
By US Geological Survey (USGS). The original modular finitedifference groundwater flow model (MODFLOW) simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined (McDonald and Harbaugh, 1988). An easier to use version MODFLOW96 is also available. Source code is available.
MODFLOW88 (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). The original modular finitedifference groundwater flow model (MODFLOW) simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined (McDonald and Harbaugh, 1988). An easier to use version MODFLOW96 is also available. Source code is available.
MODFLOW96 (for DOS)
By US Geological Survey (USGS). The modular finitedifference groundwater flow model (MODFLOW) simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined (McDonald and Harbaugh, 1988; Harbaugh and McDonald, 1996). The program was constructed in the early 1980s and has continually evolved since then with development of many new packages and related programs for groundwater studies. Currently, MODFLOW is the most widely used program in the world for simulating groundwater flow. Source code is available.
MODFLOW96 (for Silicon Graphics Indigo)
By US Geological Survey (USGS). The modular finitedifference groundwater flow model (MODFLOW) simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined (McDonald and Harbaugh, 1988; Harbaugh and McDonald, 1996). The program was constructed in the early 1980s and has continually evolved since then with development of many new packages and related programs for groundwater studies. Currently, MODFLOW is the most widely used program in the world for simulating groundwater flow. Source code is available.
MODFLOW96 (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). The modular finitedifference groundwater flow model (MODFLOW) simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined (McDonald and Harbaugh, 1988; Harbaugh and McDonald, 1996). The program was constructed in the early 1980s and has continually evolved since then with development of many new packages and related programs for groundwater studies. Currently, MODFLOW is the most widely used program in the world for simulating groundwater flow. Source code is available.
MODFLOW96 (for UNIX)
By US Geological Survey (USGS). The modular finitedifference groundwater flow model (MODFLOW) simulates steady and nonsteady flow in an irregularly shaped flow system in which aquifer layers can be confined, unconfined, or a combination of confined and unconfined (McDonald and Harbaugh, 1988; Harbaugh and McDonald, 1996). The program was constructed in the early 1980s and has continually evolved since then with development of many new packages and related programs for groundwater studies. Currently, MODFLOW is the most widely used program in the world for simulating groundwater flow. Source code is available.
MODFLOWGUI (for Windows 95/98 or NT)
By US Geological Survey (USGS). Preprocessor and postprocessor graphicaluser interfaces for preparing MODFLOW96 and MOC3D input data and viewing model output for use within Argus Open Numerical Environments (Argus ONE). Source code is available.
MODFLOWP (for Data General AViiON)
By US Geological Survey (USGS). A version of the U.S. Geological Survey modular, threedimensional, finitedifference, groundwater flow model (MODFLOW), which, with the ParameterEstimation Package, can be used to estimate parameters by nonlinear regression. The following MODFLOW model inputs can be estimated: layer transmissivity, storage, coefficient of storage, hydraulic conductivity, and specific yield; vertical leakance; horizontal and vertical anisotropy; hydraulic conductance of the River, StreamflowRouting, GeneralHead Boundary, and Drain Packages; areal recharge; maximum evapotranspiration; pumpage; and the hydraulic head at constanthead boundaries. Source code is available. Replace by MODFLOW2000.
MODFLOWP (for DOS)
By US Geological Survey (USGS). A version of the U.S. Geological Survey modular, threedimensional, finitedifference, groundwater flow model (MODFLOW), which, with the ParameterEstimation Package, can be used to estimate parameters by nonlinear regression. The following MODFLOW model inputs can be estimated: layer transmissivity, storage, coefficient of storage, hydraulic conductivity, and specific yield; vertical leakance; horizontal and vertical anisotropy; hydraulic conductance of the River, StreamflowRouting, GeneralHead Boundary, and Drain Packages; areal recharge; maximum evapotranspiration; pumpage; and the hydraulic head at constanthead boundaries. Source code is available. Replace by MODFLOW2000.
MODFLOWP (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). A version of the U.S. Geological Survey modular, threedimensional, finitedifference, groundwater flow model (MODFLOW), which, with the ParameterEstimation Package, can be used to estimate parameters by nonlinear regression. The following MODFLOW model inputs can be estimated: layer transmissivity, storage, coefficient of storage, hydraulic conductivity, and specific yield; vertical leakance; horizontal and vertical anisotropy; hydraulic conductance of the River, StreamflowRouting, GeneralHead Boundary, and Drain Packages; areal recharge; maximum evapotranspiration; pumpage; and the hydraulic head at constanthead boundaries. Source code is available. Replaced by MODFLOW2000.
MODPATH (for DOS)
By US Geological Survey (USGS). A particletracking postprocessing model for MODFLOW that was developed to compute threedimensional flow paths using output from steadystate or transient groundwaterflow simulations by MODFLOW, the U.S. Geological Survey finitedifference groundwaterflow model. Source code is available.
MODPATH (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). A particletracking postprocessing model for MODFLOW that was developed to compute threedimensional flow paths using output from steadystate or transient groundwaterflow simulations by MODFLOW, the U.S. Geological Survey finitedifference groundwaterflow model. Source code is available.
MODPATH (for UNIX)
By US Geological Survey (USGS). A particletracking postprocessing model for MODFLOW that was developed to compute threedimensional flow paths using output from steadystate or transient groundwaterflow simulations by MODFLOW, the U.S. Geological Survey finitedifference groundwaterflow model. Source code is available.
MOFAT (for DOS)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. A twodimensional, finite element model for simulating coupled multiphase flow and multicomponent transport in planar or radically symmetric vertical sections. MOFAT evaluates flow and transport for water, nonaqueous phase liquid (NAPL), and gas.
MT3DMS
By The Hydrology Group at The University of Alabama. A modular 3D multispecies transport model for simulation of advection, dispersion, and chemical reactions of contaminants in groundwater systems.
MULTIMDP (MULTIMED Daughter Process) (for DOS)
By US Environmental Protection Agency, Center for Exposure Assessment Modeling (CEAM). The Multimedia Exposure Assessment Model (MULTIMED) for exposure assessment simulates the movement of contaminants leaching from a waste disposal facility. The MULTIMED model has been modified (MULTIMDP) to simulate the transport and fate of first and secondgeneration transformation (daughter) products that migrate from a waste source through the unsaturated and saturated zones to a downgradient receptor well.
NAPL Simulator  2D (DOS)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. NAPL Simulator conducts a simulation of the contamination of soils and aquifers which results from the release of organic liquids commonly referred to as NonAqueous Phase Liquids (NAPLS).
NAPL Simulator  3D (DOS)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. NAPL Simulator conducts a simulation of the contamination of soils and aquifers which results from the release of organic liquids commonly referred to as NonAqueous Phase Liquids (NAPLS.
Natural Attenuation Software (NAS)
By Virginia Tech. A screening tool to estimate remediation timeframes for monitored natural attenuation (MNA) to lower groundwater contaminant concentrations to regulatory limits, and to assist in decisionmaking on the level of source zone treatment in conjunction with MNA using sitespecific remediation objectives. NAS consists of a combination of analytical and numerical solute transport models.
PAT
By Integrated GroundWater Modeling Center (IGWMC). PAT is an analytical model for the computation and graphical representation of pathlines and travel times of groundwater in an infinite or semiinfinite homogeneous and isotropic confined aquifer. The computed steadystate flow field can include arbitrary pumping and injection wells superimposed with a natural homogeneous regional flow which is consistent with the boundary chosen.
PEST (Parameter ESTimation)
By US Environmental Protection Agency, Center for Exposure Assessment Modeling (CEAM). PEST is a modelindependent parameter estimation package which can communicate with any model through the model's own input and output files. PEST can be used for nonlinear parameter estimation and predictive analysis in many different fields of study including ground and surface water hydrology, geophysics, engineering and others. DOSbased.
PESTAN (for DOS)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. PESTAN is used to estimate the vertical migration of dissolved organic solutes through the vadose zone to ground water. Estimates are based on a closedform analytical solution of the advectivedispersivereactive transport equation. The model is intended for use in conducting initial screening assessments of the potential for contamination of groundwater from currently registered pesticides and those submitted for registration.
PHAST (for Windows)
By US Geological Survey (USGS). A 3dimensional model for simulating groundwater flow, solute transport, and multicomponent geochemical reactions.
PHAST (RPM file for Linux)
By US Geological Survey (USGS). A 3dimensional model for simulating groundwater flow, solute transport, and multicomponent geochemical reactions.
PHAST (tar.gz file for Linux)
By US Geological Survey (USGS). A 3dimensional model for simulating groundwater flow, solute transport, and multicomponent geochemical reactions.
PHREEQC (for Linux)
By US Geological Survey (USGS). A program for aqueous geochemical calculations that can perform speciation, inverse, reactionpath, and 1D advective reactiontransport modeling. UNIX source code is available.
PHREEQC (for Mac)
By US Geological Survey (USGS). A program for aqueous geochemical calculations that can perform speciation, inverse, reactionpath, and 1D advective reactiontransport modeling. UNIX source code is available.
PHREEQC (for Windows)
By US Geological Survey (USGS). A program for aqueous geochemical calculations that can perform speciation, inverse, reactionpath, and 1D advective reactiontransport modeling. Source code is available.
PHREEQC (generic UNIX version)
By US Geological Survey (USGS). A program for aqueous geochemical calculations that can perform speciation, inverse, reactionpath, and 1D advective reactiontransport modeling.
PHREEQCI (for Windows)
By US Geological Survey (USGS). A graphical user interface for PHREEQC, a multipurpose geochemical program that can perform speciation, inverse, reactionpath, and 1D advective reactiontransport modeling. For Windows.
RADMOD (for Data General AViiON)
By US Geological Survey (USGS). A preprocessor to the program MODFLOW for simulation of axisymmetric problems. Source code is available.
RADMOD (for DOS)
By US Geological Survey (USGS). A preprocessor to the program MODFLOW for simulation of axisymmetric problems. Source code is available.
RADMOD (for Silicon Graphics Indigo)
By US Geological Survey (USGS). A preprocessor to the program MODFLOW for simulation of axisymmetric problems. Source code is available.
RADMOD (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). A preprocessor to the program MODFLOW for simulation of axisymmetric problems. Source code is available.
SHARP (for Data General AViiON)
By US Geological Survey (USGS). A quasithreedimensional, numerical finitedifference model to simulate freshwater and saltwater flow separated by a sharp interface in layered coastal aquifer systems. Source code is available.
SHARP (for DOS)
By US Geological Survey (USGS). A quasithreedimensional, numerical finitedifference model to simulate freshwater and saltwater flow separated by a sharp interface in layered coastal aquifer systems. Source code is available.
SHARP (for Silicon Graphics Indigo)
By US Geological Survey (USGS). A quasithreedimensional, numerical finitedifference model to simulate freshwater and saltwater flow separated by a sharp interface in layered coastal aquifer systems. Source code is available.
SHARP (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). A quasithreedimensional, numerical finitedifference model to simulate freshwater and saltwater flow separated by a sharp interface in layered coastal aquifer systems. Source code is available.
SHARP (for Windows)
By US Geological Survey (USGS). A quasithreedimensional, numerical finitedifference model to simulate freshwater and saltwater flow separated by a sharp interface in layered coastal aquifer systems. Source code is available.
SPAW
By US Department of Agriculture, Natural Resources Conservation Service. SPAW (Soil, Plant, Atmosphere, Water) is a water budgeting tool for farm fields, ponds and inundated wetlands. The SPAW model performs daily hydrologic water budgeting using the SCS Runoff Curve Number method.
SUTRA (for Windows)
By US Geological Survey (USGS). A finiteelement simulation model for saturatedunsaturated, fluiddensitydependent groundwater flow with energy transport or chemicallyreactive singlespecies solute transport. SUTRA may be employed for areal and crosssectional modeling of saturated groundwater flow systems, and for crosssectional modeling of unsaturated zone flow. SUTRA Version 2D3D.1 includes both 2D and 3D simulation capability. The 2D portion of the code represents the same hydrologic processes as earlier versions and is conceptually unchanged, and the 3D portion of the code represents the same processes as the 2D portion, but in three spatial dimensions.
SUTRAGUI (for Windows 95/98 and NT)
By US Geological Survey (USGS). Preprocessor and postprocessor graphicaluser interface for preparing SUTRA input data and for viewing model output for use within Argus Open Numerical Environments (Argus ONE). Source code is available.
UCODE (for DOS/Windows)
By International Ground Water Modeling Center (IGWMC) and US Geological Survey. A computer code for universal inverse modeling
UCODE (for UNIX  compressed)
By International Ground Water Modeling Center (IGWMC) and US Geological Survey. A computer code for universal inverse modeling
UTCHEM (PC version)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. Originally a threedimensional finite difference model for multiphase flow, transport and chemical flooding, the UTCHEM code has been modified to transform it into a general purpose NAPL simulator. Appropriate physical, chemical and biological process models have been incorporated into the simulator to create a 3D multiphase multicomponent model capable of simulating the fate and transport of NAPL's in the saturated and unsaturated zones of aquifers.
UTCHEM (UNIX version)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. Originally a threedimensional finite difference model for multiphase flow, transport and chemical flooding, the UTCHEM code has been modified to transform it into a general purpose NAPL simulator. Appropriate physical, chemical and biological process models have been incorporated into the simulator to create a 3D multiphase multicomponent model capable of simulating the fate and transport of NAPL's in the saturated and unsaturated zones of aquifers.
VLEACH (for DOS)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. VLEACH is a onedimensional, finite difference model for making preliminary assessments of the effects on ground water from the leaching of volatile, sorbed contaminants through the vadose zone. The program models four main processes: liquidphase advection, solidphase sorption, vaporphase diffusion, and threephase equilibration. Modeling results in an overall, areaweighted assessment of groundwater impact.
VS2DI (for Windows)
By US Geological Survey (USGS). Simulates water flow and solute transport in variably saturated porous media. Source code is available.
WhAEM2000 for Windows
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. WhAEM2000 is a public domain, groundwater flow model designed to facilitate capture zone delineation and protection area mapping in support of the State's Wellhead Protection Programs (WHPP) and Source Water Assessment Planning (SWAP) for public water supplies in the United States.
WHPA (for DOS)
By US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Center for Subsurface Modeling Support. WHPA is a semianalytical groundwater flow simulation program used for delineating capture zones in a wellhead protection area. The program consists of four computational modules (RESSQC, MWCAP, GPTRAC, MONTEC). WHPA is applicable to homogeneous aquifers exhibiting twodimensional, steady groundwater flow in an areal plane and appropriate for evaluating multiple aquifer types (i.e., confined, leakyconfined, and unconfined).
WODA (Well Outline and Design Aid)
By Group for Numerical Analysis, Jaroslav Cerni Institute. WODA (Well Outline and Design Aid) is a simulator of variably saturated welldriven groundwater flow in an anisotropic discontinuous environment with miscible displacements, heat transfer, variable density, sorption, degradation etc. WODA does not have its own graphical user interface, but it can work with groundwater models constructed using Lizza interface.
ZONEBUDGET (for Data General AViiON)
By US Geological Survey (USGS). Computes subregional water budgets using results from the MODFLOW groundwater flow model. Source code is available.
ZONEBUDGET (for DOS)
By US Geological Survey (USGS). Computes subregional water budgets using results from the MODFLOW groundwater flow model. Source code is available.
ZONEBUDGET (for Silicon Graphics Indigo)
By US Geological Survey (USGS). Computes subregional water budgets using results from the MODFLOW groundwater flow model. Source code is available.
ZONEBUDGET (for Sun SPARCstation Solaris)
By US Geological Survey (USGS). Computes subregional water budgets using results from the MODFLOW groundwater flow model. Source code is available.
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