Please enable JavaScript to view this site.

ModelMuse Help

Navigation: Online Guide to MODFLOW > Groundwater Flow Process > Boundary Condition Packages > Head-Dependent Flux Boundary Packages

GHB - General-Head Boundary Package

Scroll Prev Top Next More

Abbreviation in Name file

GHB

Purpose

The General-Head Boundary package is used to simulate head-dependent flux boundaries.  In the General-Head Boundary package the flux is always proportional to the difference in head.

Documentation

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: U.S. Geological Survey Open-File Report 00-92, 121 p.

Harbaugh, A.W., 2005, MODFLOW-2005, the U.S. Geological Survey modular ground-water model -- the Ground-Water Flow Process: U.S. Geological Survey Techniques and Methods 6-A16. https://doi.org/10.3133/tm6A16

Time-varying-parameters.pdf

release.txt

modpath.txt

Related Packages

Head-Dependent Flux Boundary packages

General-Head Boundary Observation package

Supported in

MODFLOW-2000

MODFLOW-2005

MODFLOW-LGR

MODFLOW-CFP

MODFLOW-NWT

MODFLOW-OWHM

Other Notes

Special care must be taken when constructing the GHB package input file if the observations are used.  See discussion of "Observations at Cells Having More Than One Head-Dependent Boundary Feature Represented by the Same Package" in the GBOB input file.

Input Instructions

Input to the General-Head Boundary (GHB) Package is read from the file that has file type "GHB" in the name file. Optional variables are shown in brackets. All variables are free format if the option “FREE” is specified in the Basic Package input file; otherwise, the non-optional variables have 10-character fields and the optional variables are free format.

FOR EACH SIMULATION

Data Set 0

[#Text]

Item 0 is optional—“#” must be in column 1. Item 0 can be repeated multiple times.

Data Set 1a

[ PARAMETER NPGHB MXL]

This optional item must start with the word “PARAMETER”.

Data Set 1b-1 (MODFLOW-OWHM only)

[TABFILE NTAB FILEIO TIMEOPTION]

 

Data Set 1b-2 (MODFLOW-OWHM only)

[TABNAM TABLOCATION]

READ NTAB TIMES IF NTAB>0

 

Data Set 2

MXACTB IGHBCB [Option]

Repeat Items 3 and 4 for each NPGHB parameter.

Data Set 3

[PARNAM PARTYP Parval NLST [INSTANCES  NUMINST]]

If PARNAM is to be a time-varying parameter, the keyword “INSTANCES” and a value for NUMINST must be entered.

Data Set 4a

INSTNAM

Item 4a is read only if PARNAM is time-varying. NUMINST repetitions of Item 4 (parts a and b) are read. After each repetition of Item 4a, NLST repetitions of Item 4b are read.

Data Set 4b

Layer Row Column Bhead  Condfact [xyz] [TABNAM TSFAC]

NLST repetitions of Item 4b are required; they are read by module ULSTRD. (SFAC of the ULSTRD utility module applies to Condfact). The NLST repetitions of Item 4b follow each repetition of Item 4a when PARNAM is time-varying.

 

TABNAME and TSFAC are only available in MODFLOW-OWHM.

FOR EACH STRESS PERIOD

Data Set 5

ITMP NP

Data Set 6

Layer Row Column Bhead  Cond [xyz]  [TABNAM TSFAC]

ITMP repetitions of Item 6 are read by module ULSTRD if ITMP > 0. (SFAC of the ULSTRD utility module applies to Cond.) Item 6 is not read if ITMP is negative or 0.

 

TABNAME and TSFAC are only available in MODFLOW-OWHM.

Data Set 7

[Pname [Iname]]

Item 7 is repeated NP times. It is not read if NP is negative or 0. Iname is read if Pname is a time-varying parameter.