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Online Guide to MODFLOW

Navigation: Groundwater Flow Process

BAS6 - Basic Package

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Abbreviation in Name file

BAS6

Purpose

The Basic package is used to specify certain data used in all models. These include

1.the locations of active, inactive, and specified head cells,

2.the head stored in inactive cells, and

3.the initial heads in all cells.

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

release.txt

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, variously p.

RevisedMF2005Input.pdf

Hanson, R.T., Boyce, S.E., Schmid, Wolfgang, Hughes, J.D., Mehl, S.M., Leake, S.A., Maddock, Thomas, III, and Niswonger, R.G., 2014, One-Water Hydrologic Flow Model (MODFLOW-OWHM): U.S. Geological Survey Techniques and Methods 6–A51, 120 p., http://dx.doi.org/10.3133/tm6A51.

Related Packages

Specified-Head Flow Observation input file

Flow and Head Boundary package

Time-Variant Specified-Head package

Supported in

MODFLOW-2000

MODFLOW-2005

MODFLOW-LGR

MODFLOW-CFP

MODFLOW-NWT

MODFLOW-OWHM

Common Errors

There should be a hydraulic connection between all active cells.

Other Notes

The Basic package input file is required in all models.

IBOUND may require special treatment in some cases.

Specified heads specified in the Basic package can be overridden by those specified in the Time-Variant Specified-Head package and the Flow and Head Boundary package.

Input Instructions

Basic Package Input for the Groundwater Flow Process Basic (BAS) Package except for output control input is read from the file that is specified with “BAS6” as the file type. The file type has been changed from that used in MODFLOW-96, which was “BAS”, because the input data are not compatible.

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 1

Options (199 text characters)

If there are no options to specify, then a blank record must be included for Item 1.

Data Set 2

IBOUND(NCOL,NROW) or (NCOL,NLAY) -- U2DINT

If not a cross section, a layer variable is read for each layer in the grid. If a cross section, NLAY rows of NCOL values are read.

Data Set 3

Data Set 4

STRT(NCOL,NROW) or (NCOL,NLAY) -- U2DREL

If not a cross section, a layer variable is read for each layer in the grid. If a cross section, NLAY rows of NCOL values are read.

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