GMS:MODFLOW Packages Supported in GMS

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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,

SMS
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

MODFLOW is divided into a series of components called "packages." Each package performs a specific task. The input for each package is generally contained in a separate file. The MODFLOW packages supported by GMS are listed in the following tables.

The MODFLOW packages to be used in the MODFLOW simulation are specified in the Packages dialog. This dialog is accessed in the Global Options\Basic Package dialog. Some of the packages are always required for a simulation and some are optional. One of the flow model packages and one of the solver packages must be selected. Each of the boundary condition/source/sink packages is optional.

For any package not currently supported in GMS, the file associated with that package will be ignored when the model is imported. However, GMS keeps track of unsupported packages it encounters when reading the name file and, when the project is saved, GMS lists the unsupported packages in the name file and copies the unsupported package files from the old directory to the new directory.

The MODFLOW Packages dialog.

After specifying packages for a MODFLOW simulation, the package parameters for each package can be reached through the MODFLOW menu; or by right-clicking on the package icon MODFLOW Package Icon.svg in the Project Explorer and selecting the Properties command.

Global Options & Output

Abrev Name Package/File Name USGS Description Always Req'd? Extension
MFN Name file [1] The MODFLOW name file. GMS uses "mfn" as the extension. Yes *.mfn
BAS6 Basic Package [2] Used to specify the grid dimensions, the computational time steps, and an array identifying which packages are to be used. Yes *.ba6
DIS Discretization File [3] The Discretization File is used to specify certain data used in all models. These include, the number of rows, columns and layers, the cell sizes, the presence of Quasi-3D confining beds, the time discretization. Yes *.dis
OUT1 Output Control [4] Controls what information is to be output from MODFLOW and when it is to be output. No *.oc

Flow Packages

Interfaces to four different flow packages are provided in GMS: the block centered flow (BCF), the layer property flow (LPF), the hydrogeologic unit flow (HUF), and the upstream weighting (UPW) packages. One of these four packages must be selected in the Packages dialog.

Abrev Name Package Name USGS Description Always Req'd? Extension
BCF6 Block Centered Flow Package [5] Performs the cell by cell flow calculations. The input to this package includes layer types and cell attributes such as storage coefficients and transmissivity. Parameters for sensitivity analysis or parameter estimation are NOT supported. Yes1 *.bcf
LPF Layer Property Flow Package [6] Performs the cell by cell flow calculations. The input to this package includes layer types and cell attributes such as storage coefficients and transmissivity. Yes1 *.lpf
UPW Upstream Weighting Flow Package [7] Based on the LPF package. Modified to provide a linear formulation that can be used with the NWT solver. Yes1 *.upw
HUF Hydrogeologic Unit Flow Package [8] Defines the model stratigraphy in a grid independent fashion (in the vertical direction). Yes1 *.huf

1 One of the flow packages must be used.

Solver Packages

Abrev Name Package Name USGS Description Always Req'd? Extension
GMG Geometric Multi-Grid [9] The Geometric Multigrid Solver is used to solve the finite difference equations in each step of a MODFLOW stress period. Yes1 *.gmg
SIP1 Strongly Implicit Procedure [10] The Strongly Implicit Procedure package is used to solve the finite difference equations in each step of a MODFLOW stress period. Yes1 *.sip
PCG Preconditioned Conjugate Gradient Method [11] The Preconditioned Conjugate-Gradient package is used to solve the finite difference equations in each step of a MODFLOW stress period. Yes1 *.pcg
PCGN Preconditioned Conjugate Gradient Solver with Improved Nonlinear Control [12] The Preconditioned Conjugate-Gradient package is used to solve the finite difference equations in each step of a MODFLOW stress period. Yes1 *.pcgn
SOR1 Slice-Successive Overrelaxation Method [13] The Slice-Successive Overrelaxation package is used to solve the finite difference equations in each step of a MODFLOW stress period. Yes1 *.sor
SAMG or LMG Algebraic Multi-Grid for Systems Solver [14] The LMG or Link-AMG package is used to solve the finite difference equations in each step of a MODFLOW stress period. Yes1 *.lmg
DE4 Direct Solver [15] The DE4 package is used to solve the finite difference equations in each step of a MODFLOW stress period. Yes1 *.de4
NWT Newton Solver [16] The NWT package is used to solve the finite difference equations in each step of a MODFLOW-NWT stress period. Yes1 *.nwt
SMS Sparse Matrix Solver [17] The SMS package is used to solve the finite volume equations in each step of a MODFLOW-USG stress period. Yes1 *.sms

1 One of these solvers must be selected in the Packages dialog.

Once a solver has been selected, the appropriate solver package dialog can be accessed through one of the solver commands (LMG, SIP, PCG2, or SSOR) in the MODFLOW menu. The default values shown in each dialog are typically adequate.

For more information on Solver Packages visit: http://water.usgs.gov/nrp/gwsoftware/modflow2000/MFDOC/index.html

Optional Packages

Abrev Name Package Name USGS Description Always Req'd? Extension
BFH Boundary Flow and Head Package [18] Used with MODFLOW-LGR to use coupled flows and heads when running parent or child model independently. No *.bfh_hed, *.bfh_flw
CLN CLN Process MODFLOW-USG process to simulate Connected Linear Network. No *.cln
DRN1 Drain Package [19] Simulates drain type boundary conditions. No *.drn
DRT1 Drain Return Package [20] Simulates drain return type boundary conditions. No *.drt
EVT1 Evapotranspiration Package [21] Simulates the effect of evapotranspiration in the vadose zone. No *.evt
ETS1 Evapotranspiration Segments Package [22] "allows simulation of evapotranspiration with a user-defined relation between evapotranspiration rate and hydraulic head."[1] No *.ets
GAGE Gage Package [23] Allows SFR and lake gaging stations. Gaging station prints time series values for gage location. No *.gag
GHB1 General Head Boundary Package [24] Simulates a general purpose head-dependent source/sink. Commonly used to simulate lakes. No *.ghb
GNC Ghost Node Correction Package Only in MODFLOW-USG, corrects for cells whose connector does not perpendicularly bisect the face. No *.gnc
HFB1 Horizontal Flow Barrier Package [25] Simulates the effect of horizontal flow barriers such as sheet piles and slurry trenches. No *.hfb
LAK3 Lake Package [26] A more sophisticated alternative to the typical approach of using the General head package to simulate the effect of lakes and reservoirs. Computes the stage based on the water budget unlike the GHB. No *.lak
MNW1 Multi-Node Well 1 Package [27] older revision of MNW package used to simulate wells that extend over more than one cell. No *.mnw
MNW2 Multi-Node Well 2 Package [28] updated revision of MNW1 package used to simulate wells that extend over more than one cell. No *.mnw2
RCH1 Recharge Package [29] Simulates recharge to the groundwater from precipitation. No *.rch
RIV1 River Package [30] Simulates river type boundary conditions. No *.riv
SFR2 Streamflow-Routing Package [31] Simulates the exchange of water between the aquifer and surficial streams. Includes routing and automatic computation of stage. Parameters for sensitivity analysis or parameter estimation are NOT supported. No *.sfr
STR1 Stream-Routing Package [32] Simulates the exchange of water between the aquifer and surficial streams. Includes routing and automatic computation of stage. Parameters for sensitivity analysis or parameter estimation are NOT supported. No *.str
CHD1 Time Variant Specified Head Package [33] Simulates specified head boundary conditions where the head is allowed to vary with time. No *.chd
SUB1 Subsidence Package [34] Simulates simulates aquifer compaction and land subsidence. No *.sub
SWI2 Seawater Intrusion Package [35] Simulates variable-density seawater intrusion in MODFLOW-2005. No *.swi
WEL1 Well Package [36] Simulates injection/extraction wells. No *.wel
UZF1 Unsaturated-Zone Flow Package [37] Simulate percolation of water through the unsaturated zone. No *.uzf

Other Files

Other files that GMS reads and writes with MODFLOW simulations.

File Name Description Extension
MFS MODFLOW "Super" file, created by GMS to keep track of extra information GMS needs. *.mfs
MFW MODFLOW World file, created by GMS to keep track of the geographic location of a MODFLOW model. *.mfw
PRJ Projection file in ArcGIS well-known text format specifying a geographic coordinate system. *.prj
H5 An HDF5 formatted file containing array and list data referenced from other package files. See MODFLOW_with_HDF5 for more information *.h5
ASP An Advanced Spatial Parameterization file (unavailable in USG) used with a special version of MODFLOW modified to use PEST. *.asp
PARAM Extra information about the parameters used by GMS and our modified version of MODFLOW. *.param
M2P Used by MF2PEST.EXE program. *.m2p

Output Files

Standard Extensions for OUTPUT files.

Package Extension
*.ccf
Drawdown *.drw
Global *.glo
Head *.hed
Output *.out

If a fort.# file occurs the MODFLOW file was written to the given unit number.

If a file has an underscore (*_...) followed by an extension refer to pages 29 and 30 of the MODFLOW Documentation linked here:MF2K Obs-Sen-Pes

Notes