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

Integer

NBDTIM is the number of times at which flow and head will be specified for all selected cells.

•If NBDTIM = 1, specified flow and head values will remain constant for the entire simulation.

•If NBDTIM > 1, specified flow and head values will be computed for each time step using linear interpolation.

Integer

NFLW is the number of cells at which flows will be specified.

Integer

NHED is the number of cells at which head will be specified.

Integer

IFHBSS is the FHB steady-state option flag.  If the simulation includes any transient-state stress periods, the flag is read but not used; in this case, specified-flow, specified-head, and auxiliary-variable values will be interpolated for steady-state stress periods in the same way that values are interpolated for transient stress periods.  If the simulation includes only steady-state stress periods, the flag controls how flow, head, and auxiliary-variable values will be computed for each steady-state solution.

•If IFHBSS = 0, values of flow, head, and auxiliary variables will be those specified for the starting time of the simulation.  This results in use of the first value in arrays FLWRAT, SBHED, and AuxVar for each respective boundary cell.

•If IFHBSS ≠ 0, values of flow, head, and auxiliary variables will be interpolated in the same way that values are computed for transient simulations.

Integer

IFHBCB is a flag and unit number.

•If IFHBCB > 0, it is the unit number on which cell-by-cell flow terms will be recorded whenever ICBCFL is set (see McDonald and Harbaugh, 1988, chap. 4, p. 14–15).

•If IFHBCB ≤ 0, cell-by-cell flow terms will not be recorded.

Integer

NFHBX1 is the number of auxiliary variables whose values will be computed for each time step for each specified-flow cell.

Integer

NFHBX2 is the number of auxiliary variables whose values will be computed for each time step for each specified-head cell.

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.

Character

VarName is the name of an auxiliary variable. Name can include up to 16 characters with no embedded blank characters.

Real

Weight is the time-weighting factor for an auxiliary variable specifying the fraction of each time step at which the value of the variable will be interpolated. Value must be in the range from 0.0 to 1.0.

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.

Character

VarName is the name of an auxiliary variable. Name can include up to 16 characters with no embedded blank characters.

Real

Weight is the time-weighting factor for an auxiliary variable specifying the fraction of each time step at which the value of the variable will be interpolated. Value must be in the range from 0.0 to 1.0.

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

Data Set 4a

IFHBUN CNSTM IFHBPT

hmtoggle_plus1Explanation of variables

Integer

IFHBUN is the unit number on which data lists will be read. The same or different unit numbers can be used to read lists in data items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Real

CNSTM is a constant multiplier for data list BDTIM (data item 4b), FLWRAT (part of data item 5b), SBHED(part of data item 7b), and auxiliary variables in data items 6b and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Integer

IFHBPT is a flag for printing values of data lists in items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

•If IFHBPT > 0 data list read at the beginning of the simulation will be printed.

•If IFHBCB ≤ 0 data list read at the beginning of the simulation will not be printed.

Data Set 4b

Real

BDTIM is simulation time at which values of specified flow and (or) values of specified head will be read. NBDTIM values are required.

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_plus1Explanation of variables

Integer

IFHBUN is the unit number on which data lists will be read. The same or different unit numbers can be used to read lists in data items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Real

CNSTM is a constant multiplier for data list BDTIM (data item 4b), FLWRAT (part of data item 5b), SBHED(part of data item 7b), and auxiliary variables in data items 6b and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Integer

IFHBPT is a flag for printing values of data lists in items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

•If IFHBPT > 0 data list read at the beginning of the simulation will be printed.

•If IFHBCB ≤ 0 data list read at the beginning of the simulation will not be printed.

Data Set 5b

Layer Row Column IAUX  FLWRAT(NBDTIM)

Integer

Layer is the layer index of specified-flow cell (data item 5b) or specified-head cell (data item 7b).

Integer

Row is the row index of specified-flow cell (data item 5b) or specified-head cell (data item 7b).

Integer

Column is the column index of specified-flow cell (data item 5b) or specified-head cell (data item 7b).

Integer

IAUX Is an integer auxiliary variable associated with each specified-flow and specified-head boundary cell. A value is read but not used in simulations of groundwater flow with MODFLOW-96. IAUX can be used by programs such as MODPATH (Pollock, 1994) to store information such as the cell face associated with the specified-flow or specified-head boundary.

Real

FLWRAT is volumetric rate of flow at specified-flow cells. A list of NBDTIM values must be specified for each of NFLW specified-flow cells.

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_plus1Explanation of variables

Integer

IFHBUN is the unit number on which data lists will be read. The same or different unit numbers can be used to read lists in data items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Real

CNSTM is a constant multiplier for data list BDTIM (data item 4b), FLWRAT (part of data item 5b), SBHED(part of data item 7b), and auxiliary variables in data items 6b and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Integer

IFHBPT is a flag for printing values of data lists in items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

•If IFHBPT > 0 data list read at the beginning of the simulation will be printed.

•If IFHBCB ≤ 0 data list read at the beginning of the simulation will not be printed.

Data Set 6b

Real

AuxVar is value of real auxiliary variable at specified-flow and specified-head cells. A list of NBDTIM values must be specified for each of NFLW specified-flow cells and for each of NHED specified-head cells.

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_plus1Explanation of variables

Integer

IFHBUN is the unit number on which data lists will be read. The same or different unit numbers can be used to read lists in data items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Real

CNSTM is a constant multiplier for data list BDTIM (data item 4b), FLWRAT (part of data item 5b), SBHED(part of data item 7b), and auxiliary variables in data items 6b and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Integer

IFHBPT is a flag for printing values of data lists in items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

•If IFHBPT > 0 data list read at the beginning of the simulation will be printed.

•If IFHBCB ≤ 0 data list read at the beginning of the simulation will not be printed.

Data Set 7b

Layer Row Column IAUX  SBHED(NBDTIM)

Integer Integer Integer Integer Real

Integer

Layer is the layer index of specified-flow cell (data item 5b) or specified-head cell (data item 7b).

Integer

Row is the row index of specified-flow cell (data item 5b) or specified-head cell (data item 7b).

Integer

Column is the column index of specified-flow cell (data item 5b) or specified-head cell (data item 7b).

Integer

IAUX Is an integer auxiliary variable associated with each specified-flow and specified-head boundary cell. A value is read but not used in simulations of groundwater flow with MODFLOW-96. IAUX can be used by programs such as MODPATH (Pollock, 1994) to store information such as the cell face associated with the specified-flow or specified-head boundary.

SBHED is an array containing NBDTIM values of the head for each specified-head cell.

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_plus1Explanation of variables

Integer

IFHBUN is the unit number on which data lists will be read. The same or different unit numbers can be used to read lists in data items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Real

CNSTM is a constant multiplier for data list BDTIM (data item 4b), FLWRAT (part of data item 5b), SBHED(part of data item 7b), and auxiliary variables in data items 6b and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

Integer

IFHBPT is a flag for printing values of data lists in items 4b, 5b, 6b, 7b, and 8b. A separate value is read for each of these data sets in data sets 4a, 5a, 6a, 7a and 8a respectively.

•If IFHBPT > 0 data list read at the beginning of the simulation will be printed.

•If IFHBCB ≤ 0 data list read at the beginning of the simulation will not be printed.

Data Set 8b

Real

AuxVar is value of real auxiliary variable at specified-flow and specified-head cells. A list of NBDTIM values must be specified for each of NFLW specified-flow cells and for each of NHED specified-head cells.