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Navigation: Online Guide to MODFLOW > Groundwater Flow Process > Boundary Condition Packages > Specified Flux Boundaries

FHB - Flow and Head Boundary Package

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Abbreviation in Name file

FHB

Purpose

The Flow and Head Boundary package is used for specified head cells and specified flow cells whose properties can vary within a stress period.

Documentation

Leake, S.A., and Lilly, M.R., 1997, Documentation of a computer program (FHB1) for assignment of transient specified-flow and specified-head boundaries in applications of the modular finite-difference ground-water flow model (MODFLOW): U.S. Geological Survey Open-File Report 97-571, 50 p.

Readme_FHB.txt

Related Packages

See: IBOUND in the Basic package

Time-Variant Specified-Head package

Well package

Recharge package

Supported in

MODFLOW-2000

MODFLOW-2005

MODFLOW-LGR

MODFLOW-CFP

MODFLOW-NWT

MODFLOW-OWHM

Other Notes

Specified heads specified in the the Flow and Head Boundary package override those specified in the the Basic and Time-Variant Specified-Head packages.

If two different specified heads are specified for the same cell with the Flow and Head Boundary package, the later one overrides the earlier one.

If two specified fluxes are specified for the same cell with the Flow and Head Boundary package, the fluxes are added together.

Programmers should know that the Flow and Head Boundary package changes the value assigned to IBOUND in the Basic package.

If the UZF package is used, IUZFBND should be set to zero for all specified head cells.

Input Instructions

Input for FHB1 is read from the file that has file type "FHB" in the name file.. All input is free format, which requires each of the numbered data groups to start on a new input record. More than one record can be used for any data group and numbers within data groups must be separated by at least one space or a comma. Integer data types cannot include a decimal point. Blank spaces are not treated as zeros. For an example annotated input data set, refer to figure 8 in Leake and Lilly 1997.

FOR EACH SIMULATION

Data Set 1

NBDTIM NFLW NHED IFHBSS  IFHBCB NFHBX1 NFHBX2

Data Set 2

VarName Weight

Omit data item 2 if NFHBX1=0. Input item 2 consists of one record for each of NFHBX1 auxiliary variables.

Data Set 3

VarName Weight

Omit data item 3 if NFHBX2=0. Input item 3 consists of one record for each of NFHBX2 auxiliary variables.

Data items 4a and 4b are required for all simulations. Include NBDTIM times in data item 4b.

Data Set 4a

IFHBUN CNSTM IFHBPT

hmtoggle_plus0Explanation of variables

Data Set 4b

Omit data items 5a and 5b if NFLW=0. Input item 5b consists of one set of numbers for each of NFLW cells. Each set of numbers includes layer, row, and column indices, an integer auxiliary variable, and NBDTIM values of specified flow.

Data Set 5a

IFHBUN CNSTM IFHBPT

hmtoggle_plus0Explanation of variables

Data Set 5b

Layer Row Column IAUX  FLWRAT(NBDTIM)

Omit data items 6a and 6b if NFHBX1=0 or if NFLW=0. Include one set of data items 6a and 6b for each of NFHBX1 auxiliary variables. Input item 6b consists of one set of numbers for each of NFLW cells. Each set includes NBDTIM values of the variable.

Data Set 6a

IFHBUN CNSTM IFHBPT

hmtoggle_plus0Explanation of variables

Data Set 6b

Omit data items 7a and 7b if NHED=0. Input item 7b consists of one set of numbers for each of NFLW cells. Each set of numbers includes layer, row, and column indices, an integer auxiliary variable, and NBDTIM values of specified head.

Data Set 7a

IFHBUN CNSTM IFHBPT

hmtoggle_plus0Explanation of variables

Data Set 7b

Layer Row Column IAUX  SBHED(NBDTIM)

Integer Integer Integer Integer Real

If the UZF package is used, IUZFBND should be set to zero for all specified head cells.

Omit data items 8a and 8b if NFHBX2=0 or if NHED=0. Include one set of data items 8a and 8b for each of NFHBX2 auxiliary variables. Input item 8b consists of one set of numbers for each of NHED cells. Each set includes NBDTIM values of the variable.

Data Set 8a

IFHBUN CNSTM IFHBPT

hmtoggle_plus0Explanation of variables

Data Set 8b