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Navigation: Online Guide to MODFLOW > Groundwater Flow Process > Subsidence

IBS - Interbed-Storage Package

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Abbreviation in Name file

IBS

Purpose

The Interbed-Storage package is used to simulate compaction of low-permeability interbeds within layers.

Documentation

Leake, S.A., and Prudic, D.E., 1991, Documentation of a computer program to simulate aquifer-system compaction using the modular finite-difference ground-water flow model: U.S. Geological Survey Techniques of Water- Resources Investigations, book 6, chap. A2, 68 p.

Related Packages

Subsidence package

SWT Subsidence and Aquifer-System Compaction Package

Supported in

MODFLOW-2000

MODFLOW-2005

MODFLOW-LGR

MODFLOW-CFP

MODFLOW-NWT

MODFLOW-OWHM

Other Notes

The Interbed Storage Package can not be used in the same model with the Subsidence and Aquifer-System Compaction (SUB) package.

Data Set 8 is only read for transient stress periods. (See Ss/tr.)

The UZF package does not take into account changes in the land surface due to subsidence.

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

Input Instructions

Input for the Interbed-Storage Package is read from a file that is specified with "IBS" as the file type listed in the name file.

FOR EACH SIMULATION

Data Set 1

IIBSCB IIBSOC

Format: I10 I10

Data Set 2

IBQ(NLAY) (Maximum of 999 layers in MODFLOW-2000; no fixed limit on the number of layers in MODFLOW-2005, MODFLOW-CFP, MODFLOW-NWT, MODFLOW-OWHM and MODFLOW-LGR)

Format: 4012 (If there are 40 or fewer layers, use one record; otherwise, use multiple records)

The following four arrays are needed to specify the material properties and initial compaction of model layers having interbed storage as indicated in the IBQ array. The four arrays are first read for the uppermost layer with interbed storage, and then continuing downward to lower layers with interbed storage.

FOR EACH LAYER WITH IBQ CODE GREATER THAN ZERO

Data Set 3

HC(NCOL,NROW) Module: UZDREL

Data Set 4

Sfe(NCOL,NROW) Module: UZDREL

Data Set 5

Sfv(NCOL,NROW) Module: UZDREL

Data Set 6

COM(NCOL,NROW) Module: UZDREL

IF IIBSOC IS GREATER THAN ZERO

Data Set 7

ISUBFM ICOMFM IHCFM ISUBUN ICOMUN IHCUN

Format: 110 110 110 110 110 110

FOR EACH TIME STEP

IF IIBSOC IS GREATER THAN ZERO and Ss/tr indicates that this is a transient stress period.

Data Set 8

ISUBPR ICOMPR IHCPR ISUBSV ICOMSV IHCSV

Format: 110 110 110 110 110 110