## MODFLOW-USG

Application:Groundwater Flow Modeling

Method:Finite Volume

Model Type:3D

Developer:U.S. Geological Survey

Why MODFLOW-USG with GMS?

GMS provides a custom interface to the MODFLOW-USG model offering a simple way to set model parameters and a graphical user interface to run the model and visualize the results. Gather background data from a variety of sources from GIS to CAD and access online data from numerous databases of maps, images, and elevation data. GMS allows you to interact with models in true 3D taking advantage of optimized OpenGL graphics and to create photo-realistic renderings and animations for PowerPoint, print, and web presentations. GMS is the only MODFLOW-USG interface that supports any unstructured grid type including nested grids and grids based on triangles, rectangles, hexagons, and other cell shapes.

*Try GMS Free for 14 Days* >*Purchase GMS with MODFLOW-USG* >

MODFLOW-USG Description:

MODFLOW-USG offers the ability to create unstructured grids in order to increase model resolution around features such as rivers and wells. By varying the resolution in a groundwater model, more detailed information may be represented in areas that matter most resulting in more accurate models with quicker runtimes.

Unstructured grid types include quadtree (nested grids), voronoi (variably sized polygon), and tri-quad (triangle and quadrilateral) grids.

MODFLOW-USG Package | Description |
---|---|

GNC | Ghost Node Correction |

CLN Process | Connected Linear Network |

BCT | Block Centered Transport |

DDF | Density Dependent Flow |

DPT | Dual Porosity Transport |

PCB | Prescribed Concentration Boundary |

TVM | Time-variant Materials (MODFLOW-USG Transport) |

**Overview of MODFLOW-USG**

*Errors in simulated heads from the a MODFLOW-USG simulation with ghost node correction.*

A version of MODFLOW, called **MODFLOW-USG** (for **U**n**S**tructured **G**rid), was developed to support a wide variety of structured and unstructured grid types, including nested grids and grids based on prismatic triangles, rectangles, hexagons, and other cell shapes. Flexibility in grid design can be used to focus resolution along rivers and around wells, for example, or to subdiscretize individual layers to better represent hydrostratigraphic units.

MODFLOW-USG is based on an underlying control volume finite difference (CVFD) formulation in which a cell can be connected to an arbitrary number of adjacent cells. To improve accuracy of the CVFD formulation for irregular grid-cell geometries or nested grids, a generalized Ghost Node Correction (GNC) Package was developed, which uses interpolated heads in the flow calculation between adjacent connected cells.

MODFLOW-USG includes a Groundwater Flow (GWF) Process, based on the GWF Process in MODFLOW-2005, as well as a new Connected Linear Network (CLN) Process to simulate the effects of multi-node wells, karst conduits, and tile drains, for example. The CLN Process is tightly coupled with the GWF Process in that the equations from both processes are formulated into one matrix equation and solved simultaneously. This robustness results from using an unstructured grid with unstructured matrix storage and solution schemes.

MODFLOW-USG also contains an optional Newton-Raphson formulation, based on the formulation in MODFLOW-NWT, for improving solution convergence and avoiding problems with the drying and rewetting of cells. Because the existing MODFLOW solvers were developed for structured and symmetric matrices, they were replaced with a new Sparse Matrix Solver (SMS) Package developed specifically for MODFLOW-USG. The SMS Package provides several methods for resolving nonlinearities and multiple symmetric and asymmetric linear solution schemes to solve the matrix arising from the flow equations and the Newton-Raphson formulation, respectively.

**Download Current Version of MODFLOW-USG**

**Documentation for MODFLOW-USG**

Panday, Sorab, Langevin, C.D., Niswonger, R.G., Ibaraki, Motomu, and Hughes, J.D., 2013, MODFLOW-USG version 1: An unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation: U.S. Geological Survey Techniques and Methods, book 6, chap. A45, 66 p., https://doi.org/10.3133/tm6A45

**Programs Related to MODFLOW-USG**

- GRIDGEN, a utility for creating layered quadtree grids for use with MODFLOW-USG.

**Superseded MODFLOW-USG Versions**

The following software is not actively supported by the USGS. The software has been superseded by the latest MODFLOW-USGS release above. The software versions below are provided online for historical reference only, and the files may contain outdated information or broken links.

**Find MODFLOW-Related Software**

Visit the MODFLOW and Related Programs page for a list of MODFLOW-related software.

**How to Cite MODFLOW-USG**

Panday, Sorab, Langevin, C.D., Niswonger, R.G., Ibaraki, Motomu, and Hughes, J.D., 2017, MODFLOW-USG version 1.4.00: An unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation: U.S. Geological Survey Software Release, 27 October 2017, https://dx.doi.org/10.5066/F7R20ZFJ

**Software License and Purchase Information**

This software is a product of the U.S. Geological Survey, which is part of the U.S. Government.

__Cost__

This software is freely distributed. There is no fee to download and (or) use this software.

__License__

Users do not need a license or permission from the USGS to use this software. Users can download and install as many copies of the software as they need.

__Public Domain__

As a work of the United States Government, this USGS product is in the public domain within the United States. You can copy, modify, distribute, and perform the work, even for commercial purposes, all without asking permission. Additionally, USGS waives copyright and related rights in the work worldwide through CC0 1.0 Universal Public Domain Dedication (https://creativecommons.org/publicdomain/zero/1.0/ ).

## GMS:MODFLOW-USG

MODFLOW | |
---|---|

Pre-processing | |

MODFLOW Commands | |

Building a MODFLOW Model | |

Map to MODFLOW | |

Calibration | |

Packages Supported in GMS | |

Saving a MODFLOW Simulation | |

Importing MODFLOW Files | |

Unsupported MODFLOW Features | |

Post-processing | |

MODFLOW Display Options | |

MODFLOW Post-Processing Viewing Options | |

Reading a MODFLOW Simulation | |

Tutorials | |

MODFLOW Tutorials | |

Packages | |

Flow: | BCF6, HUF, LPF, UPW |

Solvers: | DE4, GMG, NWT, PCG, PCGN, LMG, SIP, SOR, |

Other: | BAS6, BFH, CHD1, CLN, DRN1, DRT1, EVT1, ETS1, GAGE, GHB1, GNC, HFB1, HUF, LAK3, MNW1, MNW2, OUT1, RCH1, RIV1, SFR2, STR1, SUB1, SWI2, WEL1, UZF1 |

v • e |

Starting at GMS version 10.0, GMS supports MODFLOW-USG. MODFLOW-USG is a version of MODFLOW based on finite volume calculations, thus allowing for many different types of grid cells. This allows the model grid to more accurately match the model domain and be more efficiently refined in areas where more accuracy is desired.

MODFLOW-USG models are built using unstructured grids, or UGrids, which are a new (as of GMS 10.0) type of geometric object that can handle the wide variety of cell types supported by MODFLOW-USG.

The MODFLOW-USG model is included with all paid editions of GMS.

### Choosing MODFLOW Version

Only MODFLOW-USG is supported when using unstructured grids. MODFLOW-USG can also be used for a model using a 3D grid. Choosing to use MODFLOW-USG is done in the *MODFLOW Global/Basic Package* dialog. With a 3D grid at any time the user can switch from one MODFLOW version to another.

*MODFLOW Global/Basic Package*dialog

### Unsupported Features

Previous to GMS 10.1 there was no support for the following MODFLOW-USG features, though the CLN and GNC packages and the import feature are now supported in current versions of GMS.

- Packages/processes
- Older versions of GMS cannot read MODFLOW-USG files written by any non-GMS software. This is because there was no standard way to define the unstructured grid geometry. GMS writes a *.VTU (Visualization Toolkit unstructured grid) file with the MODFLOW files to define the grid geometry. In GMS 10.1 and later versions a model that was created outside of GMS can be imported as long as there is either a *.vtu file (VTK unstructured grid file) or a *.gsf file (Grid Specification File) present to define the grid geometry because the MODFLOW-USG native input files do not include locations of the grid nodes (unfortunately).

Additionally, PEST-ASP is currently unsupported in MODFLOW-USG

### MODFLOW-USG Files

Here are tables of some of the available input and output files for MODFLOW-USG.

- For more information on these files see the manual

Name | Description |
---|---|

MFN | MODFLOW Name File |

GLO | Global Listing File |

DIS | Discretization File |

OC | Process Output Control Option File |

BA6 | Basic Package Global Options File |

Name | Description |
---|---|

SMS | Sparse Matrix Solver |

Name | Description |
---|---|

BCF | Block-Centered Flow |

LPF | Layer Property Flow |

Name | Description |
---|---|

CHD | Time-Variant Specified-Head |

DRN | Drain |

EVT | Evapotranspiration |

GAG | Gage |

GHB | General Head Boundary |

GNC | Ghost Node Correction |

HFB | Horizontal Flow Barrier |

LAK | Lake |

RCH | Recharge |

RIV | River |

SFR | Streamflow-Routing |

STR | Stream-Routing |

SUB | Subsidence |

WEL | Process Well |

Name | Description |
---|---|

OBS | Main Observation Process Input |

DROB | Drain Observation |

CHOB | Constant-Head Flow Observation Input |

Name | Description |
---|---|

MFS | MODFLOW Super File |

MFW | GMS MODFLOW World File |

MFR | GMS MODFLOW Result Index File |

PRJ | Projection |

CSV | Cell Summary Comma Separated Value Excel |

HFF | Head and Flow File Link to MT3DMS |

H5 | Hierarchal Data Format (HDF5) Array & List Data |

M2P | MODFLOW Pest |

PARAM | Parameter Information |

Name | Description |
---|---|

CCF | Cell-to-Cell Aquifer Flow |

CCF2 | Cell-to-Cell Stream Reach Outflow |

DRW | Drawdown |

GLO | Global Listing |

HED | Head Output |

OUT | Output |

VTU | Visualization Toolkit Unstructured Grid |

Name | Description |
---|---|

_W | Weighted Residuals |

_WW | Weighted Equivalents & Weighted Observation |

_WS | Weighted Residuals and Simulated Equivalents |

_R | Unweighted Residuals |

_OS | Observed Values and Simulated Equivalents |

_B | Data Exchange File |

_NM | Weighted Residuals and Probability Plotting |

### Practical Notes

When using MODFLOW-USG to re-wet cells:

- In the
*MODFLOW SMS Solver*dialog, the*Nonlinear solution method*should be set to one of the two Newton methods. - In the
*LPF Package*dialog, each layer should be set to*Convertible Upstream*(this is essentially a Newton layer).

### External Files

### See also

## MODFLOW

**MODFLOW** is the U.S. Geological Survey modular finite-difference flow model, which is a computer code that solves the groundwater flow equation. The program is used by hydrogeologists to simulate the flow of groundwater through aquifers. The source code is freepublic domain software,^{[1]} written primarily in Fortran, and can compile and run on Microsoft Windows or Unix-like operating systems.

Since its original development in the early 1980s,^{[2]} the USGS has made four major releases, and is now considered to be the *de facto* standard code for aquifer simulation. There are several actively developed commercial and non-commercial graphical user interfaces for MODFLOW.

MODFLOW was constructed in what was in 1980's called a modular design. This means it has many of the attributes of what came to be called object-oriented programming. For example, capabilities (called "packages") that simulate subsidence or lakes or streams, can easily be turned on and off and the execution time and storage requirements of those packages go away entirely. If a programmer wants to change something in MODFLOW, the clean organization makes it easy. Indeed, this kind of innovation is exactly what was anticipated when MODFLOW was designed.

Importantly, the modularity of MODFLOW makes it possible for different Packages to be written that are intended to address the same simulation goal in different ways. This allows differences of opinion about how system processes function to be tested. Such testing is an important part of multi-modeling, or alternative hypothesis testing. Models like MODFLOW and SUMMA, a program from NCAR that simulates surface processes like rainfall-runoff and gully erosion, make this kind of testing more definitive and controlled. This results because other aspects of the program remain the same. Tests become more definitive because they become less prone to being influenced unknowingly by other numerical and programming differences.

### Groundwater flow equation[edit]

The governing partial differential equation for a confined aquifer used in MODFLOW is:

where

### Finite difference[edit]

The finite difference form of the partial differential in a discretized aquifer domain (represented using rows, columns and layers) is:

where

- is the hydraulic head at cell
*i*,*j*,*k*at time step*m* *CV*,*CR*and*CC*are the hydraulic conductances, or branch conductances between node*i*,*j*,*k*and a neighboring node- is the sum of coefficients of head from source and sink terms
- is the sum of constants from source and sink terms, where is flow out of the groundwater system (such as pumping) and is flow in (such as injection)
- is the specific storage
- are the dimensions of cell
*i*,*j*,*k*, which, when multiplied, represent the volume of the cell; and - is the time at time step
*m*

This equation is formulated into a system of equations to be solved as:

where

or in matrix form as:

where

*A*is a matrix of the coefficients of head for all active nodes in the grid- is a vector of head values at the end of time step m for all nodes in the grid; and
- is a vector of the constant terms,
*RHS*, for all nodes of the grid.

### Limitations[edit]

- The water must have a constant density, dynamic viscosity (and consequently temperature) throughout the modelling domain (SEAWAT is a modified version of MODFLOW which is designed for density-dependent groundwater flow and transport)

### Versions[edit]

^{[3]}which illustrates a computer surrounded by modules and arraysused by MODFLOW. This was said at the time to resemble a "component stereo system".

### "Modular Model"[edit]

The USGS throughout the 1970s had developed several hundred models, written in different dialects of FORTRAN. At the time, it was common practice to rewrite a new model to fit the need of a new groundwater scenario. The concept for MODFLOW was originally designed in 1981 to provide a common *modular* groundwater model, which could be compiled on multiple platforms without major (or any) modification, and can read and write common formats. Different aspects of the groundwater system would be handled using the modules, similar to the idea of a "component stereo system". The original name of the code was "The USGS Modular Three-Dimensional Finite-Difference Ground-Water Flow Model", or informally as "The Modular Model." The name MODFLOW was coined several years after the initial code development, which started in 1981.^{[2]}

The first version of MODFLOW^{[3]} was published on December 28, 1983, and was coded entirely in FORTRAN 66. The source code for this version is listed in USGS Open File Report 83-875 referred to above.

### MODFLOW-88[edit]

This version of MODFLOW^{[4]} was rewritten in FORTRAN 77, and was originally released on July 24, 1987. The current version of MODFLOW-88 is 2.6, released on September 20, 1996.

*MODPATH*, was initially developed in 1989 to post-process the steady-state MODFLOW-88 data to determine three-dimensional pathlines of particles. This innovation has been indispensable for the fields of contaminanthydrogeology. It is still used as a post-processor in recent versions of MODFLOW.

A separate program, *MODFLOWP*, was developed in 1992 to estimate various *parameters* used in MODFLOW. This program was eventually built into MODFLOW-2000.

### MODFLOW-96[edit]

MODFLOW-96 (version 3.0) was originally released on December 3, 1996, and is a cleaned-up and revised continuation of MODFLOW-88.^{[5]}^{[6]} There are three final releases of MODFLOW-96:

- MODFLOW-96 (version 3.3, May 2, 2000)
- MODFLOW-96h (version 3.3h, July 10, 2000), with HYDMOD package
- MODFLOWP (version 3.2, Oct 9, 1997), MODFLOW-96 with parameter-estimation

Several graphical interfaces were first developed using the MODFLOW-96 code.

### MODFLOW-2000[edit]

MODFLOW-2000 (version 1.0; version numbering was reset) was released on July 20, 2000, which merged MODFLOWP and HYDMOD codes into the main program and has integrated observation, sensitivity analysis, parameter estimation, and uncertainty evaluation capabilities.^{[7]} Many new packages and enhancements were also included, including new solvers, stream and saturated flow packages. The internal design concepts also changed from previous versions, such that *packages*, *processes* and *modules* are distinct. This version was coded in a mixture of FORTRAN 77, Fortran 90, and one solver was programmed in C. MODFLOW-2000 can also be compiled for parallel computing, which can allow multiple processors to be used to increase model complexity and/or reduce simulation time. The parallelization capability is designed to support the sensitivity analysis, parameter estimation, and uncertainty analysis capabilities of MODFLOW-2000.

The final version of MODFLOW-2000 (or *MF2K*) is version 1.19.01, released on March 25, 2010. There are four related or branched codes based on MODFLOW-2000:

- MF2K-GWM or GWM-2000 (version 1.1.4, May 31, 2011, branched from mf2k 1.17.2), with groundwater management capability using optimization
- MF2K-FMP (version 1.00, May 19, 2006, based on mf2k 1.15.03), with Farm Process
- MF2K-GWT (version 1.9.8, October 28, 2008, based on MF2K 1.17.02), groundwater flow and solute-transport model
- SEAWAT (version 4.00.05, October 19, 2012), variable-density flow and transport processes
- VSF (version 1.01, July 5, 2006), variably saturated flow

### MODFLOW-2005[edit]

MODFLOW-2005 ^{[8]} differs from MODFLOW-2000 in that the sensitivity analysis, parameter estimation, and uncertainty evaluation capabilities are removed. Thus, the support for these capabilities now falls to "clip on" codes that are supported externally to the MODFLOW support effort. In addition, the code was reorganized to support multiple models within one MODFLOW run, as needed for the LGR (Local Grid Refinement) capability.^{[9]} MODFLOW-2005 is written primarily in Fortran 90 and C, with C being used for one solver.

The current version of MODFLOW-2005 is version 1.12.00, released on February 3, 2017. Related or branched codes include:

- MODFLOW-CFP (version 1.8.00, February 23, 2011), conduit flow process to simulate turbulent or laminar groundwater flow conditions
- MODFLOW-LGR (version 2.0, September 19, 2013), local grid refinement
- GWM-2005 (version 1.4.2, March 25, 2013), groundwater management capability using optimization
- MF2005-FMP2 (version 1.0.00, October 28, 2009), estimate dynamically integrated supply-and-demand components of irrigated agriculture as part of the simulation of surface-water and ground-water flow
- MODFLOW-NWT(version 1.1.3, August 1, 2017), Newton formulation for solving problems involving drying and rewetting nonlinearities of the unconfined groundwater-flow equation.
^{[10]}

### MODFLOW-OWHM[edit]

MODFLOW-OWHM^{[11]} (version 1.00.12, October 1, 2016), The One-Water Hydrologic Flow Model (MODFLOW-OWHM, MF-OWHM or One-Water^{[12]}), developed cooperatively between the USGS and the U.S. Bureau of Reclamation, is a fusion of multiple versions of MODFLOW-2005 (NWT, LGR, FMP, SWR, SWI) into ONE version, contains upgrades and new features and allows the simulation of head-dependent flows, flow-dependent flows, and deformation dependent flows that collectively affect conjunctive use of water resources.

Being based on the MODFLOW-2005 source code, MODFLOW-OWHM is the second core release of MODFLOW-2005. MODFLOW-OWHM provides the ability to simulated demand-driven, supply-limited hydrologic systems, as commonly occur in arid agricultural areas in which the demand for water exceeds supply. When the added capabilities are not used, MODFLOW-OWHM performs exactly like MODFLOW-2005, or MODFLOW-NWT, or MODFLOW-LGR (depending on the features used).

There is an online input guide that explains the input for the packages that MODFLOW-OWHM supports and formal documentation is at the USGS Publications Warehouse.

### MODFLOW-USG[edit]

All version of MODFLOW listed above are constructed on what is called a structured grid. That is, the grid is composed of rectilinear blocks. The only exception is the LGR capability, which allows locally refined grids to be inserted into the structure of a "parent" grid. The local area is again composed of rectilinear blocks, but the blocks are smaller. Experimentation with a much more flexible grid structure resulted in the release of MODFLOW-USG^{[13]} (version 1.3.00, December 1, 2015), designed to be adapted to a wide range of grid variations using unstructured grids. MODFLOW-USG was replaced with MODFLOW 6, which provided grid capabilities with and intermediate level of flexibility.

### MODFLOW 6[edit]

MODFLOW 6 (MF6), released in 2017, is the sixth core version of MODFLOW to be released by the USGS.^{[14]} This release is a rewrite of MODFLOW-USG following an object oriented programming paradigm in Fortran, and provides a platform that includes the capabilities from several previous MODFLOW-2005 versions, including MODFLOW-NWT, MODFLOW-USG, and MODFLOW-LGR. There are still features lacking in the current release that are supported in MODFLOW-2005, such as subsidence, and stream flow routing (SFR) only supports rectangular wetted perimeters.^{[15]} The current version is 6.2.1, released February 19, 2021.^{[16]}

### Packages[edit]

The names in this table are the labels used to turn MODFLOW capabilities on and off via a key input file. Most capabilities have many alternatives or can be omitted, but the ones related to the BASIC Package are always required. Many of the capabilities introduced are supported in later versions, though the grid change enabled with MODFLOW-USG and MODFLOW 6 meant that such backward compatibility was rather selective.

Name | Long name | Version introduced |
---|---|---|

Basic Package and its Components | ||

BAS | Basic Package | original |

OC | Output Control | original |

DIS | Discretization | MODFLOW-2000 (1.0) |

DISU | Unstructured Discretization | MODFLOW-USG (1.0) |

DISV | Discretization by Vertices | MODFLOW 6 (1.00) |

IC | Initial Conditions | MODFLOW 6 (1.00) |

Groundwater flow packages | ||

BCF | Block-Centered Flow Package | original |

CLN | Connected Linear Network Process | MODFLOW-USG (1.0) |

GNC | Ghost Node Correction Package | MODFLOW-USG (1.0) |

HFB | Horizontal Flow Barrier Package | MODFLOW-88 |

HUF | Hydrogeologic Unit Flow Package | MODFLOW-2000 (1.1) |

LPF | Layer-Property Flow Package | MODFLOW-2000 (1.0) |

NPF | Node Property Flow | MODFLOW 6 (1.00) |

SWI2 | Seawater Intrusion Package | MODFLOW-2005 (1.11) |

UPW | Upstream Weighting Package | MODFLOW-NWT (1.0) |

UZF | Unsaturated-Zone Flow Package | MODFLOW-2005 (1.2) |

Conjunctive Use and Land Use Simulation | ||

FMP | Farm Process | MODFLOW-FMP |

SWO | Surface Water Operations | MODFLOW-OWHM (2.0) |

Specified Head boundary packages | ||

CHD | Constant-Head Boundary / Time-Variant Specified-Head | MODFLOW-88 |

FHB | Flow and Head Boundary Package | MODFLOW-96 (3.2) |

Specified flux boundary packages | ||

FHB | Flow and Head Boundary Package | MODFLOW-96 (3.2) |

RCH | Recharge Package | original |

WEL | Well Package | original |

Head-dependent flux boundary packages | ||

DAF | DAFLOW | MODFLOW-96 |

DRN | Drain Package | original |

DRT | Drain Return Package | MODFLOW-2000 (1.1) |

ETS | Evapotranspiration Segments Package | MODFLOW-2000 (1.1) |

EVT | Evapotranspiration Package | original |

GHB | General-Head Boundary Package | original |

LAK | Lake Package | MODFLOW-2000 (1.1) |

MAW | Multi-Aquifer Well | MODFLOW 6 (1.00) |

MNW | Multi-Node, Drawdown-Limited Well Package | MODFLOW-2000 (1.11) |

RES | Reservoir Package | MODFLOW-88 (2.6) |

RIP | Riparian Evapotranspiration Package | MODFLOW-OWHM (1.0) |

RIV | River Package | original |

SFR | Streamflow-Routing Package | MODFLOW-2000 (1.14.00) |

STR | Stream Package | MODFLOW-88 |

SWR | Surface-Water Routing Process | MODFLOW-NWT 1.08 |

UZF | Unsaturated-Zone Flow Package | MODFLOW-2005 (1.2) |

Solvers | ||

DE4 | Direct Solver Package | MODFLOW-88 (2.5) |

GMG | Geometric Multigrid Solver | MODFLOW-2000 (1.15.00) |

LMG | Link-AMG Package | MODFLOW-2000 (1.4) ^{[Note 1]} |

NWT | Newton-Raphson | MODFLOW-NWT (1.0) |

PCG | Preconditioned Conjugate-Gradient Package | MODFLOW-88 |

PCGN | Preconditioned Conjugate Gradient Solver with Improved Nonlinear Control | MODFLOW-2005 (1.9.0) |

SIP | Strongly Implicit Procedure Package | original |

SMS | Sparse Matrix Solver | MODFLOW-USG (1.0) |

SOR | Slice Successive Over-Relaxation Package | original |

Miscellaneous packages | ||

GAG | Gage | MODFLOW-2000 |

HYD | HYDMOD | MODFLOW-2000 (1.1) |

IBS | Interbed-Storage | MODFLOW-88 |

KDEP | Hydraulic-Conductivity Depth-Dependence Capability | MODFLOW-2000 (1.12) |

LMT | Link-MT3DMS | MODFLOW-2000 (1.5) |

LVDA | Model-Layer Variable-Direction Horizontal Anisotropy Capability | MODFLOW-2000 (1.12) |

MVR | Water Mover | MODFLOW 6 (1.00) |

STO | Storage | MODFLOW 6 (1.00) |

SUB | Subsidence and Aquifer-System Compaction | MODFLOW-2000 (1.12) |

SWT | Subsidence and Aquifer-System Compaction Package for Water-Table Aquifers | MODFLOW-2000 (1.18) |

UTL | Utility | original |

Observation process input files | ||

OBS | Input File For All Observations | MODFLOW-2000 |

HOB | Head-Observation | MODFLOW-2000 |

DROB | Drain Observation | MODFLOW-2000 |

DTOB | Drain Return Observation | MODFLOW-2000 |

RVOB | River Observation | MODFLOW-2000 |

GBOB | General-Head-Boundary Observation | MODFLOW-2000 |

CHOB | Constant-Head Flow Observation | MODFLOW-2000 |

ADV | Advective-Transport Observation | MODFLOW-2000 (1.0) |

STOB | Stream Observation | MODFLOW-2000 |

Obsolete packages | ||

GFD | General Finite-Difference | MODFLOW-88 to 96 |

TLK | Transient Leakage | MODFLOW-88 to 96 |

**^**Due to licensing restrictions, the USGS is no longer able to publicly distribute the Algebraic Multi-Grid

### Graphical user interfaces[edit]

There are several graphical interfaces to MODFLOW, which often include the compiled MODFLOW code with modifications. These programs aid the input of data for creating MODFLOW models.

### Non-commercial interfaces[edit]

Non-commercial MODFLOW versions are free, however, their licensing usually limit the use to non-profit educational or research purposes.

- ModelMuse is a grid-independent graphical user interface from the USGS for MODFLOW 6, MODPATH, SUTRA, and PHAST version 1.51. There are no license restrictions. The source code is included.
- MODFLOW-GUI – Made by the USGS: it is updated often to match the current USGS MODFLOW development. It supports MODFLOW-96, MODFLOW-2000, MODFLOW-2005, MODPATH, ZONEBUDGET, GWT, MT3DMS, SEAWAT, and GWM. Source code for MODFLOW-GUI is included. It depends on Argus ONE: a commercial interface for constructing generic models. There are no license restrictions beyond those of Argus ONE.
- PMWIN – "Processing MODFLOW" (for Windows) – powerful freeware for MODFLOW processing and visualization, provided alongside an instructional book;
^{[17]}also available in Traditional Chinese. The license for this version is limited to non-commercial use. - mflab - mflab is a MATLAB interface to MODFLOW. The user builds and analyzes models by writing a set of MATLAB scripts. This results in flexible and efficient workflows, allowing a great deal of automation.
- iMOD - Free and open source interface developed by Deltares. iMOD contains an accelerated version of MODFLOW with fast, flexible and consistent sub-domain modeling techniques. Facilitating large, high resolution MODFLOW modeling and geo-editing of the subsurface
- FREEWAT is a free and open source, QGIS-integrated modelling platform integrating MODFLOW (MODFLOW versions integrated are MODFLOW-2005 and MODFLOW-OWHM) and the following MODFLOW-related simulation codes: MT3DMS, MT3D-USGS, SEAWAT, ZONE BUDGET, MODPATH, UCODE-2014. FREEWAT has been developed in the framework of the H2020 FREEWAT project (FREE and open source software tools for WATer resource management), financed by the EU Commission under the call WATER INNOVATION: BOOSTING ITS VALUE FOR EUROPE. The source code is released under a GNU GENERAL PUBLIC LICENSE, Version 2, June 1991, along with a complete set of User Manuals and tutorials.

### Commercial programs[edit]

Commercial MODFLOW programs are typically used by governments and consultants for practical applications of MODFLOW to real-world groundwater problems. Professional versions of MODFLOW are generally priced at a minimum of around $1000 and typically range upward to US$7000. This is a list of commercial programs for MODFLOW:

All current versions of these programs run only on Microsoft Windows, however previous versions of GMS (up to Version 3.1) were compiled for several Unix platforms.

### Former graphical interfaces[edit]

- Graphic Groundwater – Windows-based interface
- ModelCad – A Windows-based interface, developed by Geraghty and Miller, Inc.
- ModIME – A DOS-based interface by S.S. Papadopulos & Associates, Inc.

### See also[edit]

### References[edit]

**^**Water Webserver Team (March 5, 2014). "Software User Rights Notice".*Water Resources of the United States*. U.S. Department of the Interior, U.S. Geological Survey. Retrieved 2014-05-27.- ^
^{a}^{b}McDonald M.G. & Harbaugh, A.W. (2003). "The History of MODFLOW".*Ground Water*.**41**(2): 280–283. doi:10.1111/j.1745-6584.2003.tb02591.x. PMID 12656294. - ^
^{a}^{b}^{c}McDonald, M.G. & Harbaugh, A.W. (December 28, 1983).*A modular three-dimensional finite-difference ground-water flow model*. Open-File Report 83-875. U.S. Geological Survey. **^**McDonald, M.G. & Harbaugh, A.W. (1988).*A modular three-dimensional finite-difference ground-water flow model*(PDF). Techniques of Water-Resources Investigations, Book 6. U.S. Geological Survey.**^**Harbaugh, A.W. & McDonald, M.G. (1996a).*User's documentation for MODFLOW-96, an update to the U.S. Geological Survey modular finite-difference ground-water flow model*(PDF). Open-File Report 96-485. U.S. Geological Survey.**^**Harbaugh, A.W. & McDonald, M.G. (1996).*Programmer's documentation for MODFLOW-96, an update to the U.S. Geological Survey modular finite-difference ground-water flow model*(PDF). Open-File Report 96-486. U.S. Geological Survey.**^**Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G. (2000).*MODFLOW-2000, the U.S. Geological Survey modular ground-water model — User guide to modularization concepts and the Ground-Water Flow Process*(PDF). Open-File Report 00-92. U.S. Geological Survey.CS1 maint: multiple names: authors list (link)**^**Harbaugh, Arlen W. (2005).*MODFLOW-2005, The U.S. Geological Survey Modular Ground-Water Model—the Ground-Water Flow Process*. Techniques and Methods 6–A16. U.S. Geological Survey.**^**Mehl, Steffen (2005).*MODFLOW-2005, The U.S. Geological Survey Modular Ground-Water Model—Documentation of Shared Node Local Grid Refinement (LGR) and the Boundary Flow and Head (BFH) Package*. Techniques and Methods 6–A12. U.S. Geological Survey.**^**Niswonger, Richard G.; Panday, Sorab; Ibaraki, Motomu (2011),*MODFLOW-NWT, A Newton Formulation for MODFLOW-2005*, Techniques and Methods 6-A37, Reston, VA: U.S. Geological Survey**^**Hanson, Randall T.; Boyce, Scott E.; Schmid, Wolfgang; Hughes, Joseph D.; Mehl, Steffen W.; Leake, Stanley A.; Maddock, Thomas, III; Niswonger, Richard G. (2014),*One-Water Hydrologic Flow Model (MODFLOW-OWHM)*, Techniques and Methods 6-A51, Reston, VA: U.S. Geological Survey, p. 134CS1 maint: multiple names: authors list (link)**^**"Mf-Owhm | Modflow Owhm".**^**Panday, Sorab; Langevin, Christian D.; Niswonger, Richard G.; Ibaraki, Motomu; Hughes, Joseph D. (2013),*MODFLOW–USG Version 1: An Unstructured Grid Version of MODFLOW for Simulating Groundwater Flow and Tightly Coupled Processes Using a Control Volume Finite-Difference Formulation*, Techniques and Methods 6-A45, Reston, VA: U.S. Geological Survey**^**Hughes, Joseph D.; Langevin, Christian D.; Banta, Edward R. (2017). "Documentation for the MODFLOW 6 framework".*Techniques and Methods*. Techniques and Methods 6-A57. p. 40. doi:10.3133/tm6A57.**^**Langevin, Christian D.; Hughes, Joseph D.; Banta, Edward R.; Niswonger, Richard G.; Panday, Sorab; Provost, Alden M. (2017). "Documentation for the MODFLOW 6 Groundwater Flow Model".*Techniques and Methods*. Techniques and Methods 6-A55. doi:10.3133/tm6A55.**^**"MODFLOW 6: USGS Modular Hydrologic Model".**^**Wen-Hsing Chiang (2005).*3D-Groundwater Modeling with PMWIN*(Second ed.). Springer. doi:10.1007/3-540-27592-4. ISBN .

### External links[edit]

## Usg modflow

#### Links

#### Abstract

A new version of MODFLOW, called MODFLOW–USG (for UnStructured Grid), was developed to support a wide variety of structured and unstructured grid types, including nested grids and grids based on prismatic triangles, rectangles, hexagons, and other cell shapes. Flexibility in grid design can be used to focus resolution along rivers and around wells, for example, or to subdiscretize individual layers to better represent hydrostratigraphic units. MODFLOW–USG is based on an underlying control volume finite difference (CVFD) formulation in which a cell can be connected to an arbitrary number of adjacent cells. To improve accuracy of the CVFD formulation for irregular grid-cell geometries or nested grids, a generalized Ghost Node Correction (GNC) Package was developed, which uses interpolated heads in the flow calculation between adjacent connected cells. MODFLOW–USG includes a Groundwater Flow (GWF) Process, based on the GWF Process in MODFLOW–2005, as well as a new Connected Linear Network (CLN) Process to simulate the effects of multi-node wells, karst conduits, and tile drains, for example. The CLN Process is tightly coupled with the GWF Process in that the equations from both processes are formulated into one matrix equation and solved simultaneously. This robustness results from using an unstructured grid with unstructured matrix storage and solution schemes. MODFLOW–USG also contains an optional Newton-Raphson formulation, based on the formulation in MODFLOW–NWT, for improving solution convergence and avoiding problems with the drying and rewetting of cells. Because the existing MODFLOW solvers were developed for structured and symmetric matrices, they were replaced with a new Sparse Matrix Solver (SMS) Package developed specifically for MODFLOW–USG. The SMS Package provides several methods for resolving nonlinearities and multiple symmetric and asymmetric linear solution schemes to solve the matrix arising from the flow equations and the Newton-Raphson formulation, respectively.

Publication type | Report |
---|---|

Publication Subtype | USGS Numbered Series |

Title | MODFLOW–USG version 1: An unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation |

Series title | Techniques and Methods |

Series number | 6-A45 |

DOI | 10.3133/tm6A45 |

Year Published | 2013 |

Language | English |

Publisher | U.S. Geological Survey |

Publisher location | Reston, VA |

Contributing office(s) | Office of Groundwater |

Description | Report: vii, 68 p.; Available Software |

Larger Work Type | Report |

Larger Work Subtype | USGS Numbered Series |

Larger Work Title | Section A: Ground Water in Book 6 Modeling Techniques |

Country | United States |

Online Only (Y/N) | Y |

Additional Online Files (Y/N) | Y |

Google Analytic Metrics | Metrics page |

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