Online Guide to MODFLOW

ISWTCB is a flag and unit number.

•If ISWTCB > 0, it is the unit number to which cell-by-cell flow terms will be written when “SAVE BUDGET” or a non-zero value for ICBCFL is specified in MODFLOW Output Control (for example, Harbaugh and others, 2000, p. 52–55).

•If ISWTCB ≤ 0, cell-by-cell flow terms will not be recorded.

ISWTOC is a flag and unit number.

•If ISWTOC > 0, it is the number of repetitions of item 17 to be read, each repetition of which defines a set of times steps and associated flags for printing and saving subsidence, compaction by layer, compaction by interbed system, vertical displacement, preconsolidation stress, change in preconsolidation stress, geostatic stress, change in geostatic stress, effective stress, change in effective stress, void ratio, thickness of interbeds, and layer-center elevation.

•If ISWTOC ≤ 0, subsidence, compaction, vertical displacement, preconsolidation stress, change in preconsolidation stress, geostatic stress, change in geostatic stress, effective stress, change in effective stress, void ratio, thickness of interbeds, and layer-center elevation will not be printed or saved.

NSYSTM is the number of systems of interbeds.

ITHK is a flag to determine how thicknesses of compressible sediments vary in response to changes in saturated thickness.

•If ITHK ≤ 0, thickness of compressible sediments is constant.

•If ITHK > 0, thickness of compressible sediments varies in response to changes in saturated thickness.

IVOID is a flag to determine how void ratios of compressible sediments vary in response to changes in saturated thickness.

•If IVOID ≤ 0, void ratio will be treated as a constant.

•If IVOID > 0, void ratio will be treated as a variable.

ISTPCS is a flag to determine how initial preconsolidation stress will be obtained.

•If ISTPCS ≠ 0, an array of offset values will be read in for each model layer. The offset values will be added to the initial effective stress to get initial preconsolidation stress.

•If ISTPCS = 0, an array with initial preconsolidation stress values will be read in.

ICRCC is a flag to determine how recompression and compression indices will be obtained.

•If ICRCC ≠ 0, arrays of elastic specific storage and inelastic skeletal specific storage will be read for each system of interbeds. The recompression index and compression index will not be read.

•If ICRCC = 0, arrays of recompression index and compression index will be read for each system of interbeds. Elastic skeletal specific storage and inelastic skeletal specific storage will not be read.

IZCFL is a flag to specify whether or not initial calculated values of layer-center elevation will be printed.

•If IZCFL > 0, array will be printed using format code specified by variable IZCFM.

•If IZCFL ≤ 0, array will not be printed.

IZCFM is a code for the format in which layer-center elevation will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

IGLFL is a flag to specify whether or not initial calculated values of geostatic stress will be printed.

•If IGLFL > 0, array will be printed using format specified by variable IGLFM.

•If IGLFL ≤ 0, array will not be printed.

IGLFM is a code for the format in which geostatic stress will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

IESTFL is a flag to specify whether or not initial calculated values of effective stress will be printed.

•If IESTFL > 0, array will be printed using format specified by variable IESTFM.

•If IESTFL = 0, array will not be printed.

IESTFM is a code for the format in which effective stress will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

IPCSFL is a flag to specify whether or not initial calculated values of preconsolidation stress will be printed.

•If IPCSFL > 0, array will be printed using format specified by variable IPCSFM.

•If IPCSFL ≤ 0, array will not be printed.

IPCSFM is a code for the format in which preconsolidation stress will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

ISTFL is a flag to specify whether or not initial equivalent storage properties will be printed for each system of interbeds. If ICRCC≠0, the equivalent storage properties that can be printed are recompression and compression indices (Cr and Cc), which are calculated from elastic and inelastic skeletal specific storage (Sske and Sskv). If ICRCC=0, equivalent storage properties that can be printed are elastic and inelastic skeletal specific storage, which are calculated from the recompression and compression indices.

•If ISTFL > 0, array will be printed using format specified by variable ISTFM.

•If ISTFL ≤ 0, array will not be printed.

ISTFM is a code for the format in which equivalent storage properties will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Ifm1 is a code for the format in which subsidence will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun1 is the unit number to which subsidence will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm2 is a code for the format in which compaction by layer will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun2 is the unit number to which compaction by layer will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm3 is a code for the format in which compaction by system will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun3 is the unit number to which compaction by system will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm4 is a code for the format in which vertical displacement will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun4 is the unit number to which vertical displacement will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm5 is a code for the format in which preconsolidation stress will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun5 is the unit number to which preconsolidation stress will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm6 is a code for the format in which change in preconsolidation stress will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun6 is the unit number to which change in preconsolidation stress will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm7 is a code for the format in which geostatic stress will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun7 is the unit number to which geostatic stress will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm8 is a code for the format in which change in geostatic stress will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun8 is the unit number to which change in geostatic stress will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm9 is a code for the format in which effective stress will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun9 is the unit number to which effective stress will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm10 is a code for the format in which change in effective stress will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun10 is the unit number to which change in effective stress will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm11 is a code for the format in which void ratio will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun11 is the unit number to which void ratio will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm12 is a code for the format in which thickness of compressible sediments will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun12 is the unit number to which thickness of compressible sediments will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

Ifm13 is a code for the format in which layer-center elevation will be printed.

Format codes for IZCFM, IGLFM, IESTFM, IPCSFM, ISTFM, Ifm1, Ifm2, Ifm3, … Ifm13 are as follows:

(Positive values for wrap format; negative values for strip format.)

Iun13 is the unit number to which layer-center elevation will be written if it is saved on disk.

The file type of this file must be listed as DATA(BINARY) in the Name file.

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

ISP1 is the starting stress period in the range of stress periods to which output flags Ifl1---Ifl26 apply. If the value of ISP1 is less than 1, the SUB-WT Package will change the number to 1.

ISP2 is the ending stress period in the range of stress periods and time steps to which output flags Ifl1---Ifl26 apply. If the value of ISP2 is greater than NPER (the number of stress periods in the simulation), the SUB-WT Package will change the number to NPER.

ITS1 is the starting time step in the range of time steps in each of the stress periods ISP1 through ISP2 to which output flags Ifl1 through Ifl26 apply. If the value of ITS1 is less than 1, the SUB-WT Package will change the number to 1.

ITS2 is the ending time step in the range of time steps in each of stress periods ISP1---ISP2 to which output flags Ifl1 through Ifl26 apply. If the value of ITS2 is greater than the number of time steps in a given stress period, the SUB-WT Package will change the number to the number of time steps in that stress period.

Ifl1 is the output flag for printing subsidence for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl1 < 0, use default or previously defined settings of Ifl1 for printing subsidence.

•If Ifl1 = 0, do not print subsidence.

•If Ifl1 > 0, print subsidence.

Ifl2 is the output flag for saving subsidence to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl2 < 0, use default or previously defined settings of Ifl2 for saving subsidence.

•If Ifl2 = 0, do not save subsidence.

•If Ifl2 > 0, save subsidence.

Ifl3 is the output flag for printing compaction by layer for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl3 < 0, use default or previously defined settings of Ifl3 for printing compaction by layer.

•If Ifl3 = 0, do not print compaction by layer.

•If Ifl3 > 0, print compaction by layer.

Ifl4 is the output flag for saving compaction by layer to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl4 < 0, use default or previously defined settings of Ifl4 for saving compaction by layer.

•If Ifl4 = 0, do not save compaction by layer.

•If Ifl4 > 0, save compaction by layer.

Ifl5 is the output flag for printing compaction by interbed system for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl5 < 0, use default or previously defined settings of Ifl5 for printing compaction by interbed system.

•If Ifl5 = 0, do not print compaction by interbed system.

•If Ifl5 > 0, print compaction by interbed system.

Ifl6 is the output flag for saving compaction by interbed system to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl6 < 0, use default or previously defined settings of Ifl6 for saving compaction by interbed system.

•If Ifl6 = 0, do not save compaction by interbed system.

•If Ifl6 > 0, save compaction by interbed system.

Ifl7 is the output flag for printing vertical displacement for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl7 < 0, use default or previously defined settings of Ifl7 for printing vertical displacement.

•If Ifl7 = 0, do not print vertical displacement.

•If Ifl7 > 0, print vertical displacement.

Ifl8 is the output flag for saving vertical displacement to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl8 < 0, use default or previously defined settings of Ifl8 for saving vertical displacement.

•If Ifl8 = 0, do not save vertical displacement.

•If Ifl8 > 0, save vertical displacement.

Ifl9 is the output flag for printing preconsolidation stress for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl9 < 0, use default or previously defined settings of Ifl9 for printing preconsolidation stress.

•If Ifl9 = 0, do not print preconsolidation stress.

•If Ifl9 > 0, print preconsolidation stress.

Ifl10 is the output flag for saving preconsolidation stress to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl10 < 0, use default or previously defined settings of Ifl10 for saving preconsolidation stress.

•If Ifl10 = 0, do not save preconsolidation stress.

•If Ifl10 > 0, save preconsolidation stress.

Ifl11 is the output flag for printing change in preconsolidation stress for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl11 < 0, use default or previously defined settings of Ifl11 for printing change in preconsolidation stress.

•If Ifl11 = 0, do not print change in preconsolidation stress.

•If Ifl11 > 0, print change in preconsolidation stress.

Ifl12 is the output flag for saving change in preconsolidation stress to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl12 < 0, use default or previously defined settings of Ifl12 for saving change in preconsolidation stress.

•If Ifl12 = 0, do not save change in preconsolidation stress.

•If Ifl12 > 0, save change in preconsolidation stress.

Ifl13 is the output flag for printing geostatic stress for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl13 < 0, use default or previously defined settings of Ifl13 for printing geostatic stress.

•If Ifl13 = 0, do not print geostatic stress.

•If Ifl13 > 0, print geostatic stress.

Ifl14 is the output flag for saving geostatic stress to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl14 < 0, use default or previously defined settings of Ifl14 for saving geostatic stress.

•If Ifl14 = 0, do not save geostatic stress.

•If Ifl14 > 0, save geostatic stress.

Ifl15 is the output flag for printing change in geostatic stress for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl15 < 0, use default or previously defined settings of Ifl15 for printing change in geostatic stress.

•If Ifl15 = 0, do not print change in geostatic stress.

•If Ifl15 > 0, print change in geostatic stress.

Ifl16 is the output flag for saving change in geostatic stress to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl16 < 0, use default or previously defined settings of Ifl16 for saving change in geostatic stress.

•If Ifl16 = 0, do not save change in geostatic stress.

•If Ifl16 > 0, save change in geostatic stress.

Ifl17 is the output flag for printing effective stress for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl17 < 0, use default or previously defined settings of Ifl17 for printing effective stress.

•If Ifl17 = 0, do not print effective stress.

•If Ifl17 > 0, print effective stress.

Ifl18 is the output flag for saving effective stress to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl18 < 0, use default or previously defined settings of Ifl18 for saving effective stress.

•If Ifl18 = 0, do not save effective stress.

•If Ifl18 > 0, save effective stress.

Ifl19 is the output flag for printing change in effective stress for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl19 < 0, use default or previously defined settings of Ifl19 for printing change in effective stress.

•If Ifl19 = 0, do not print change in effective stress.

•If Ifl19 > 0, print change in effective stress.

Ifl20 is the output flag for saving change in effective stress to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl20 < 0, use default or previously defined settings of Ifl20 for saving change in effective stress.

•If Ifl20 = 0, do not save change in effective stress.

•If Ifl20 > 0, save change in effective stress.

Ifl21 is the output flag for printing void ratio for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl21 < 0, use default or previously defined settings of Ifl21 for printing void ratio.

•If Ifl21 = 0, do not print void ratio.

•If Ifl21 > 0, print void ratio.

Ifl22 is the output flag for saving void ratio to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl22 < 0, use default or previously defined settings of Ifl22 for saving void ratio.

•If Ifl22 = 0, do not save void ratio.

•If Ifl22 > 0, save void ratio.

Ifl23 is the output flag for printing compressible bed thickness for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl23 < 0, use default or previously defined settings of Ifl23 for printing compressible bed thickness.

•If Ifl23 = 0, do not print compressible bed thickness.

•If Ifl23 > 0, print compressible bed thickness.

Ifl24 is the output flag for saving compressible bed thickness to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl24 < 0, use default or previously defined settings of Ifl24 for saving compressible bed thickness.

•If Ifl24 = 0, do not save compressible bed thickness.

•If Ifl24 > 0, save compressible bed thickness.

Ifl25 is the output flag for printing layer-center elevation for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl25 < 0, use default or previously defined settings of Ifl25 for printing layer-center elevation.

•If Ifl25 = 0, do not print layer-center elevation.

•If Ifl25 > 0, print layer-center elevation.

Ifl26 is the output flag for saving layer-center elevation to an unformatted disk file for the set of time steps specified by ISP1, ISP2, ITS1, and ITS2.

•If Ifl26 < 0, use default or previously defined settings of Ifl26 for saving layer-center elevation.

•If Ifl26 = 0, do not save layer-center elevation.

•If Ifl26 > 0, save layer-center elevation.