WEL - Well Package

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Abbreviation in Name file

WEL

Purpose

The Well package is used to simulate a specified flux to individual cells and specified in units of length3/time.

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

Niswonger, R.G., Panday, Sorab, and Ibaraki, Motomu, 2011, MODFLOW-NWT, A Newton formulation for MODFLOW-2005: U.S. Geological Survey Techniques and Methods 6-A37, 44 p.

release.txt for MODFLOW-NWT

Related Packages

The Recharge package is used to simulate a specified flux distributed over the top of the model and specified in units of length/time.  Within MODFLOW, these rates are multiplied by the horizontal area of the cells to which they are applied to calculate the volumetric flux rates.

The Flow and Head Boundary package can be used to simulate a specified flux to particular cells specified in units of length3/time and varying as a function of time within stress periods.

Supported in

MODFLOW-2000

MODFLOW-2005

MODFLOW-LGR

MODFLOW-CFP

MODFLOW-NWT

MODFLOW-OWHM

Other Notes

In MODFLOW-NWT version 1.1 WEL parameters can not be used if NUMTAB  > 0

MODFLOW-NWT version 1.1 does not read auxiliary variables for wells when tabfiles are used.

Input Instructions

Input to the Well (WEL) Package is read from the file that has type "WEL" 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 1

[ PARAMETER NPWEL MXL]

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

Options Block (MODFLOW-NWT version 1.1

Note that the following changes to the Well Package input no longer supports previous input files that read the key word option SPECIFY in Data Set 2B. In MODFLOW-NWT version 1.1.3 backwards compatibility was restored by allowing the options to be read in Data Set 2B.

The input format for specifying the keyword (character) variable SPECIFY has changed.This character variable is now specified within the OPTIONS block that is specified between Data Set 0 and Data Set 1. A new character variable option was added that allows users to specify pumping rates using separate tabular input files for each well. Each tabular input file consists of a series of simulation times and pumping rates that should begin with time equal to zero. The applied pumping rate will be interpolated from the tabular input file using the times at the end and beginning of the time step. Options must be proceeded with the "OPTIONS" specification and followed by the "END" specification. Characters can be specified as upper or lower case.

In MODFLOW-NWT version 1.3, backwards compatibility was restored by allowing the SPECIFY keyword to again be specified in Option in data set 2A.

Optional character variables for WELL in any order:

OPTIONS

[SPECIFY PHIRAMP IUNITRAMP]

[TABFILES NUMTAB MAXVAL]

END

 

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

[TABFILE NTAB FILEIO TIMEOPTION]

 

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

[TABNAM TABLOCATION]

READ NTAB TIMES IF NTAB>0

 

Data Set 1a-3 (MODFLOW-OWHM only)

[PrintOption NLNK]

READ IF NTAB>0

 

Data Set 1a-4 (MODFLOW-OWHM only)

[LAYER ROW COL TABNAM TSFAC]

READ NLNK TIMES IF NLNK>0

Note: If you have multiple wells located at the same layer, row, and column that are linked to different tabfiles, then the tabfiles will be applied in the order that they appear here. For example if you specify 3 identical wells with the same layer, row and column, but with each linked to a different tabfile and then have a stress period with only 2 of the 3 wells identical wells specified. When this occurs only the first two tabfiles read in here are applied and the third is ignored. This does not apply to identical wells that use the same tabfile, but have different scale factors.

Data Set 2a

MXACTW IWELCB [Option]

Data Set 2b

Data set 2b can only be specified in versions of MODFLOW that include the NWT solver. PHIRAMP is only used if NWT is the selected solver. Otherwise, it is ignored.

[SPECIFY PHIRAMP IUNITRAMP]

Repeat Items 3 and 4 for each NPWEL 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 Qfact [xyz]

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

FOR EACH STRESS PERIOD

Data Set 5

ITMP NP

 

MODFLOW-NWT version 1.1

IF TABFILES is specified then DATA SET 6 is replaced with the following NUMTAB lines for stress period 1 only. DATA SET 6 is not required for stress periods following the first stress period when the TABFILES option is used.

[TABUNIT TABVAL TABLAY TABROW TABCOL]  

#repeat this line NUMTAB times for stress period 1.

 

Data Set 6

Layer Row Column Q [xyz]

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

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.