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HUF2 - Hydrogeologic-Unit Flow Package

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Abbreviation in Name file

HUF2

Purpose

The Hydrogeologic-Unit Flow package is used to specify properties controlling flow between cells.  It allows you to specify these properties by "hydrogeologic unit".  The unit boundaries are not required to correspond to layer boundaries.  The properties of individual cells is synthesized from the properties of the hydrogeologic units that intersect the cell.

Documentation

Anderman, E.R., and Hill, M.C., 2000, MODFLOW-2000, the U.S. Geological Survey Modular Ground-Water Model - Documentation of the Hydrogeologic-Unit Flow (HUF) Package: U.S. Geological Survey Open-File Report 00-342, 89 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

Anderman, E.R., Kipp, K.L., Hill, M.C., Valstar, Johan, and Neupauer, R.M., 2002, MODFLOW-2000, the U.S. Geological Survey modular ground-water model -- Documentation of the Model-Layer Variable-Direction Horizontal Anisotropy (LVDA) capability of the Hydrogeologic-Unit Flow (HUF) Package: U.S. Geological Survey Open-File Report 02-409, 60 p.

Anderman, E.R., and Hill, M.C., 2003, MODFLOW-2000, the U.S. Geological Survey modular ground-water model -- Three additions to the Hydrogeologic-Unit Flow (HUF) Package: Alternative storage for the uppermost active cells, Flows in hydrogeologic units, and the Hydraulic-coductivity depth-dependence (KDEP) capability: U.S. Geological Survey Open-File Report 03-347, 36 p.

readme_HUF.txt

Related Packages

The Block-Centered Flow package (BCF) and the Layer-Property Flow package (LPF) are two other packages that can be used to specify properties controlling flow between cells.

The Horizontal Flow Barrier package (HFB) modifies the horizontal conductances between certain, specified pairs of cells.

Supported in

MODFLOW-2000

MODFLOW-2005

MODFLOW-LGR

MODFLOW-CFP

MODFLOW-NWT

MODFLOW-OWHM

Other Notes

Every model must  use one and only one of the four packages (BCF6, LPF, HUF2, and UPW) that are used to specify properties controlling flow between cells. UPW is only available in MODFLOW-NWT and MODFLOW-OWHM.

The "Model-Layer Variable-Direction Horizontal Anisotropy" capability is provided in the LVDA input file but is part of the Hydrogeologic Unit Flow package.

The "Hydraulic-Conductivity Depth-Dependence Capability" capability is provided in the KDEP input file but is part of the Hydrogeologic Unit Flow package.

The "Model-Layer Variable-Direction Horizontal Anisotropy" capability (LVDA) is incompatible with the Horizontal Flow Barrier package (HFB) and with the Sensitivity (SEN) process.

The UZF package reads values of hydraulic conductivity and specific yield from the BCF and LPF packages but not the HUF package. Therefore, the HUF2 package can not be used with the UZF package. As of MODFLOW2005 version 1.5, the UZF package can be used with the HUF2 package.

The SFR package does not support unsaturated flow when the HUF package is used.

See the Frequently Asked Questions for information on how to read data from binary files generated by MODFLOW.

The SOR solver (not included in MODFLOW-2005 and MODFLOW-LGR) doesn't work well with the wetting capability.

The vertical flow from or to a lake is calculated incorrectly when the HUF package is used. This bug is present in MODFLOW-2005 version 1.9.1 and in all earlier versions. This bug has been fixed in MODFLOW-NWT version 1.7 and MODFLOW-2005 version 1.10.

Input Instructions

Input for the Hydrogeologic Unit Flow (HUF) Package is read from the file that has type "HUF" in the name file. Free format is used for reading all values.

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

IHUFCB HDRY NHUF NPHUF  IOHUFHEADS IOHUFFLOWS

Data Set 2

Data Set 3

Data Set 4

WETFCT IWETIT IHDWET

Include Item 4 only if LAYWT indicates at least one wettable layer.

Data Set 5

WETDRY(NCOL,NROW) - U2DREL

Repeat Item 5 for each layer for which LAYWET is not 0.

Repeat Items 6-8 for each hydrogeologic unit to be defined (that is, NHUF times).

Data Set 6

Data Set 7

TOP(NCOL,NROW) Arrays are read by the array-reading utility module - U2DREL

Data Set 8

THCK(NCOL,NROW) Arrays are read by the array-reading utility module - U2DREL

Data Set 9

HGUNAM HGUHANI HGUVANI

Repeat Item 9 for each hydrogeologic unit.

Repeat Items 10-11 for each parameter to be defined (that is, NPHUF times).

Data Set 10

PARNAM PARTYP Parval NCLU

Data Set 11

HGUNAM Mltarr Zonarr IZ

Each Item 11 record is called a parameter cluster. Repeat Item 11 NCLU times.

Data Set 12

PRINT HGUNAM PRINTCODE PRINTFLAGS

Item 12 is optional and is included only for hydrogeologic units for which printing is desired. Item 12 must start with the word PRINT.