Online Guide to MODFLOW

ZONE - Zone File

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ZONE - Zone File

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ZONE - Zone File

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Abbreviation in Name file



The Zone File  is used to specify zone arrays which can be used to specify the cells in a layer variable that are associated with a parameter.


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.

Supported in


Other Notes

Zone arrays are used in the ADV2, ETS, EVT, HUF2, KDEP, LPF, LVDA, RCH, and UPW input files.

Input Instructions

Input to define zone arrays is read from the file that is specified with "ZONE" as the file type. Zone arrays can be used to specify the cells in a layer variable that are associated with a parameter.


Data Set 0


Item 0 is optional—“#” must be in column 1. Item 0 can be repeated multiple times.

Text—is a character variable (199 characters) that starts in column 2. Any characters can be included in Text. The “#” character must be in column 1. Except for the name file, lines beginning with # are restricted to these first lines of the file. Text is printed when the file is read.

Data Set 1


NZN—is the number of zone arrays to be defined.  In MODFLOW-2000, the maximum number of zone arrays is 1000.

an optional print flag that when set >0 writes all zone arrays to file called “ZONE_Arrays.txt.” This will not occur if ZONEPRINT is not present or set to < 1. ZONEPRINT is only included in MODFLOW-OWHM.


Items 2-3 are repeated for each of the NZN zone arrays.

Data Set 2

ZONNAM—is the name of a zone array. This name can consist of 1 to 10 characters and is not case sensitive; that is, any combination of the same characters with different case are equivalent. The name “ALL” should not be used for a zone array because it is a reserved word.

Data Set 3


IZON—is a zone array.