# iMOD User Manual version 5.2 (html)

#### 8.3ISG-FUNCTIONS

##### 8.3.1ISGEXPORT-Function

The ISGEXPORT function reads an ISG file and export the entire content into readable files.

Example 1

FUNCTION=ISGEXPORT
ISGFILE=D:\MODEL\RIVER.ISG
IEXPORT=0

##### 8.3.2ISGIMPORT-Function

The ISGIMPORT function generates an ISG file from files created via the IEXPORT=0 option on the iMODBatch Function ISGEXPORT, see section 8.3.1.

Example 1

FUNCTION=ISGIMPORT
ISGEXPORT=D:\MODEL\RIVER_ISG.TXT
ISGFILE=D:\RIVER.ISG
ISGDOUBLE=1

##### 8.3.3GEN2ISG-Function

The GEN2ISG function reads a GEN file and creates a ISG file. There are two ways to use this function; IUSEDAT=1 and IUSDAT=0. These will be explained below.

Use IUSEDAT=1 to force using the *.DAT file (with GEN file information).

Use IUSEDAT=0 if you do not have a *.DAT file (with GEN file information).

Example 1

FUNCTION=GEN2ISG
FUNCTION=GEN2ISG
GENFNAME=d:\Model\Data\Shape_data\river_lines.gen
IUSEDAT=0
IDFSUMMER=d:\Model\Basic_data\SUMMER_LEVEL_RIVER.IDF
IDFWINTER=d:\Model\Data\Basic_data\WINTER_LEVEL_RIVER.IDF
IDFBOTTOM=d:\Model\Data\Basic_data\BODEMHOOGTE_RIVER.IDF
SAMPLE_DISTANCE=25.0
CCFFNAME=d:\Model\Data\Basic_data\CROSS-SECTION.CCF
IDFRESISTANCE=d:\Model\Data\Basic_data\RIV_RESISTANCE.idf
IDFINFILTRATIONFACTOR=d:\Model\Data\Basic_data\INFFACTOR_RIVER.IDF
OUTFILE=d:\Model\Data\ISG_data\River.isg

Above an example is given how to use the GEN2ISG. This example will generate and ISG file based on river levels, bottom elevation, resistance, infiltration factor and the location of the river segments. The ISG will contain the following information: as many as cross-sections per river segment as there are unique ID-numbers in CCFFNAME related file, calculation nodes on each segment intersection and segment nodes as much as there are coordinate points defined in the GEN file.

##### 8.3.4ISGGRID-Function

Use this function to rasterize the selected ISG-files into IDF-files that can be used by iMODFLOW in a runfile.

Example:

FUNCTION=ISGGRID
ISGFILE_IN=D:\PO.ISG
CELL_SIZE=100.0
NODATA=-999.99
ISAVE=1,1,1,1,0,0,0,0,0,0,0,0
IPERIOD=2
SDATE=19980101
EDATE=19980131
OUTPUTFOLDER=D:\PO_GRIDS

The example above will rasterize the entire ISG for the period of the 1$^{\rm th}$ of January up to the 31$^{\rm th}$ of January 1998 on a 100x100 meter grid.

Use this function to add cross-sections to an existing ISG-file (see section 9.9.3 for more information about the content of an ISG-file and storage of cross-sections). The methodology is twofold:

• 1. One-dimensional cross-sections:

Reading cross-sectional information from a text file for one-dimensional cross-sections.

• 2. Two-dimension cross-sections:

Reading two-dimensional bathymetry from an IDF-file for areas that are defined by a pointer IDF. All existing cross-section will be used to assign two-dimensional cross-sections. The dimension of the bathymetry will be overruling the dimensions of the pointer IDF.

Example 1 (one-dimensional cross-sections):

ISGFILE_IN=D:\iMOD-DATA\MAAS.ISG
CROSSSECTION_IN=D:\DATA\CROSS.TXT
WIDTH_IDF=D:\DATA\WIDTH.IDF
MAXDIST=2.5
ISGFILE_OUT=D:\iMOD-DATA\MAAS_RENEWEDCROSSSECTIONS.ISG

The example above will add cross-sections based on the entered CROSS.TXT file that specifies a cross-section for “New Cross” as follows:

12000.0,45300.0,”New Cross”,-10.0,-5.0,-2.5,2.5,7.5,12.0,5.0,3.0,2.0,1.0,2.5,5.0

the results will be saved in MAAS_RENEWEDCROSSSECTION.ISG.

Example 2 (two-dimensional cross-sections):

CROSS_PNTR=D:\DATA\PNTR.IDF
CROSS_BATH=D:\DATA\BATHEMETRY.IDF
ISGFILE_OUT=D:\iMOD-DATA\MAAS_RENEWEDCROSSSECTIONS.ISG

The example above will transform the existing cross sections with two-dimensional definitions based on the pointerfile read in CROSS_PNTR and the corresponding bathymetry read in BATHEMETRY.IDF.

##### 8.3.6ISGSIMPLIFY-Function

Use this function to reduce the amount of calculation points in a ISD file (part of the ISG-files, see section 9.9.2). iMOD will eliminate calculation points that do not add significant information to the declination of waterlevels, in other words, whenever the gradient of the waterlevel can be described by less calculation points, iMOD will locate those calculation points that are able to represent the original waterlevel most optimally. iMOD will use the mean waterlevels for all calculation nodes to determine a mean descent of waterlevels along a segment. Simplification will be carried out for segments as a whole. Whenever segments will be very short, this function will have a minor effect.

Example:

FUNCTION=ISGSIMPLIFY
ISGFILE_IN=D:\iMOD-DATA\MAAS.ISG
ZTOLERANCE=0.10
NODATA=-999.99
ISGFILE_OUT=D:\iMOD-DATA\MAAS_SIMPLIFIED.ISG

The example above will reduce the amount of calculation points such that the simplified waterlevel will be differ more than 0.10 from the original one, the results will be saved in MAAS_SIMPLIFIED.ISG.

Use this function to perform changes to an existing ISG.

Example:

SESFILE=D:\iMOD-DATA\ISGEDIT\ISG-change-stage.SES
LOGFILE=D:\iMOD-DATA\ISGEDIT\ISG-LOG.TXT
OUTNAME=D:\iMOD-DATA\RIV\ISG_new

The example above will produce new ISG files based on new data in the SES file.

Use this function will add weirs to an ISG.

Example:

ISGFILE_IN=D:\RIV-DATA\LEGGER.ISG
IPFFILE_IN=D:\RIV-DATA\WEIR.IPF
ISGFILE_OUT=D:\RIV-DATA\LEGGER_V2.ISG

The example above will produce new ISG files based on new data in WEIR.IPF.

Use this function will add water levels to an ISG. Existing water levels wil be overwritten if the entered IPF with water levels has water levels for identical dates as already mentioned in the ISG file.

Example:

ISGFILE_IN=D:\RIV-DATA\LEGGER.ISG
IPFFILE=D:\RIV-DATA\WATERLEVEL.IPF
ISGFILE_OUT=D:\RIV-DATA\LEGGER_V2.ISG

The example above will produce new ISG files based on new data in WATERLEVEL.IPF.

##### 8.3.10SFRTOISG-Function

This function can be used to convert the output of the SFR package onto an ISG file. In this way the existing functionalities of ISG Edit can be used to inspect and analyse the output of the SFR package.

Not all of the above mentioned columns are converted to the ISG file, the average stream discharge (half of the sum of the Flow into Stream Reach plus the Flow out of Stream Reach) is converted from m$^3$/d to m$^3$/s. Also the stream head, depth and width are transferred to the ISG file. Those four attributes are considered to be most valuable.

Example:

FUNCTION=SFRTOISG
SFRFILE_IN=D\MODEL\SFR.ISG.
SFRFILE_OUT=D\MODEL\SFR_RESULT.ISG.
SFRFILE_IN=D\MODEL\TUT_FSFR.TXT.

The example above will produce a new ISG files based on the results of the SFR package.

##### 8.3.11IPFTOISG-Function

This function can be used to convert an IPF file with appropriate columns into an ISG suitable for the SFR package. Two following pairs of coordinates will form a single segment in the ISG file. Also, only one calculation point and cross-section will appear on each segment. The cross-section will be rectangular (4 points) based on the given stream width (see below).

Example:

FUNCTION=IPFTOISG
IPFFILE=D\DATA\STREAM.IPF.
ISGFILE=D\MODEL\SFR.ISG.
ILABELCOL=4
ISEGM=3

The example above will produce a new ISG files compatible with the SFR package, for more clarification an example is given for the IPF file as well. This file will create 2 ISG segment called S_2391526_R_1 and S_2391526_R_2. An example of the IPF file is given below:

8
X
Y
SECTION
NAME
WIDTH
WATERLEVEL
BOTTOMLEVEL
PERM
0,TXT
459420.449184,5495001.214598,252-2391526,"2391526",4.0,90.72400,89.724000,100.0
459327.814399,5495038.775708,252-2391526,"2391526",4.0,90.27100,89.271000,100.0
459235.179516,5495076.336717,252-2391526,"2391526",2.0,89.14100,88.141000,100.0