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Online Guide to MODFLOW

Abbreviation in Name file



The Multi-Node, Drawdown-Limited Well package is used to simulate wells that extend over more than one cell.  Most commonly, this would represent cells that extend over several layers.


Halford, K.J. and Hanson R.T., 2002, User Guide for the Drawdown-Limited, Multi-Node Well (MNW) Package for the U.S. Geological Survey’s Modular Three-Dimensional Finite-Difference Ground-Water Flow Model, Versions MODFLOW-96 and MODFLOW-2000t: U.S. Geological Survey Open-File Report 02-293, 33 p.


release.txt for MODFLOW-2005

Related Packages

Well package

MNW2 package

Head-Dependent Flux Boundary packages

Supported in







Other Notes

The MNW1 and MNW2 packages can not both be used in the same simulation.

Input Instructions

Input for the multi-node, drawdown-limited well package (MNW Package) is initiated by specifying in the NAME file (Harbaugh and McDonald, 1996). Data are read from MNW Package input files as 256-character-wide, alphanumeric records to facilitate the addition of comments within the model input files and the use of keys to identify input variables. All integer, real, and character variables are read from the alphanumeric records. The records are initially read by the subroutine NCREAD. Records that begin with a ‘#’ sign in the first column are treated as comment records, are not passed to any other routines, and are discarded. Once NCREAD has acquired a valid data record, the record is checked for a ‘!!’ sign that designates the beginning of any in-line comments on a data-input record. If a ‘!!’ sign is detected, the ‘!!’ sign and all text to the right of the ‘!!’ sign are removed from the record before passing it to any other routines.

Alphanumeric strings are used in the MNW Package to identify variables (keys) and make logical decisions (flags). Specification of these keys and flags is case insensitive because all letters are capitalized before performing any logical tests. Keys precede the variable to be read, which is acquired by identifying the key and reading the first value that follows the key. Logical decisions are based on the presence (true) or absence (false) of a flag. In this report, bold, upper-case letters are used to denote the part of the key that is tested. Key:data pairs that are not delimited by parentheses are mandatory and must be included, and Key:data pairs that are delimited within parentheses and are optional because default values are used if they are not specified by the user.

The MNW Package reads input data for each simulation and for each stress period as follows:


Data Set 1

MXMNW IWL2CB IWELPT [NOMOITER] REFerence SP: kspref (Required record)

Format: Integer Integer Integer [Integer] Alphanumeric key Integer

Data Set 2

LOSSTYPE (PLossMNW) (Required record)

Format: Alpanumeric Real

Data Set Unnumbered

PREFIX:MNWNAME (Optional record)

Format: Alphanumeric header record

Data Set 3a

FILE:filename WEL1:iunw1 (Optional record)

Format: Alphanumeric header record

Data Set 3b

FILE:filename BYNODE:iunby ALLTIME (Optional record)

Format: Alphanumeric header record Flag

Data Set 3c

FILE:filename QSUM:iunqs ALLTIME (Optional record)

Format: Alphanumeric header record Flag


Data Set 4


Format: I10 Alphanumeric key

Data Set 5

Layer Row Column Qdes [MN or MULTI] QWval Rw Skin  Hlim Href [DD] Iwgrp Cp: C [QCUT or Q-%CUT: Qfrcmn Qfrcmx] DEFAULT   SITE: MNWsite

Format I10 I10 I10 F10.0 Flag Real Real Real Real Real Flag Integer Real Real Real Flag Alphanumeric header record

NOTE: The first four values in data item 5 for the variables Layer, Row, Column, and Qdes are read initially as a free format. If this fails, the four values are read as fixed format entries from the first 40 columns. In all instances these values must be specified. The following eight values for the remaining variables are optional, space-delimited or comma-delimited entries but must be entered in the sequence specified for item 5. The alphanumeric flags MN and DD can appear anywhere between columns 41 and 256, inclusive. Input item 5 normally consists of one record for each well cell defined or modified. If ITMP is 0 or less, item 5 is not read and should not be specified.

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