# iMOD User Manual version 4.4 (html)

#### 5.6Subsurface Explorer

The Subsurface Explorer tool can be used to import prepared subsurface data of the Netherlands into iMOD. The data that can be loaded are stored in a database, of which the path has to be specified in the IMOD_INIT.PRF file using the keyword SUBSURFEXDBASE. Furthermore, the path to the 7-zip executable on the users computer also has to be specified in this file using the keyword 7ZIP, see Section 9.1 for more information.

Subsurface Explorer window:

Note: The window can be resized by dragging the edges in order to adjust the size of the map. When using polygons to select cells, the data will not be clipped to the polygon, it is only used to select the cells. A *.SHP file can easily be converted to a *.GEN file in order to be able to use it in the Subsurface Explorer. Simply open the file in iMOD as an overlay (iMOD Manager) and the *.SHP file will automatically be converted to a *.GEN file, which will be placed in the same directory.

The database that contains the data that is imported using the Subsurface Explorer tool should be structured as the above figure shows:

• • The data type folders, SETTINGS.TXT and PROVINCES.7Z are stored in the folder to which the IMOD_INIT.PRF file should refer (see Section 9.1).

• • The SETTINGS.TXT file contains the minimal X, minimal Y, maximum X, maximum Y and the grid size of the map that is visible on the tool. In this case the map of the Netherlands is divided into cells using a grid with a cell size of 10 km$^2$, resulting in a total of 891 cells. An example of this SETTINGS.TXT is:
10000.0
305000.0
280000.0
635000.0
10000.0

• • The map of the Netherlands is drawn using a GEN file stored in PROVINCES.7Z. The data type folders contain a zip file for each cell, containing only the data of that data type for that cell.

• • Furthermore, when applicable, the data type folder can contain a legend in LEGEND.7Z archive, containing an iMOD format legend which will then be used when plotting the data (see Section 9.16).

• • For data types that consist of many raster files, e.g. REGIS, an MDF file stored in the database in MDF.7Z, is used to be able to handle these files more conveniently (see Section 6.5).

• • Finally each data type folder also contains a SETTINGS.TXT file, in which the extension (e.g. IPF), whether a legend is present (1 for yes, 0 for no) and (only when the data type has the IPF extension) a header which should be used for the IPFs of that data type are given.

• • By using the SETTINGS.TXT files the tool can also be used for other datasets in other geographical regions and new data types can be added easily without editing the source code.

• • The names of the files in the archives containing the data of cells are only the cell number followed by the extension of the file. For example the DINO borehole data of cell 55 are stored in 55.IPF (and corresponding text files). Only raster files have an extended name which also contains one string with information about the layer the file describes, this information can for example be which geological formation the layer describes or at which depth the layer is situated. For example the geotop layer at a depth of 50 centimeters below the surface in cell 55 is named -50_55.IDF. The string on the left of the underscore can contain any character supported by the operating system, except for an underscore, because this character is used to be able to separate the additional information about the layer from the cell number.
The grid cells are numbered in the following way:

• • The data that are loaded are downloaded from the database to the user’s computer and are stored in a folder with the name of the project specified using the tool in the
IMOD_USER\SUBSURFACE_EXPLORER\directory.

• • The data that are loaded into iMOD using the Subsurface Explorer are plotted and shown in the iMOD manager, after which all iMOD functionalities can be used to analyse and edit the data.

Examples of dataset settings-files
Example AHN
IDF
0

This means that the AHN-dataset contains files of the filetype *.IDF and no predefined legend-file (*.DLF) is provided.

Satellite image
PNG
0

In this example satellite images are stored as *.png files and will be available via the iMOD TOPO-tool.

Example DINO boreholes - header file
IPF
1
5
"X-COORDINATE, M"
"Y-COORDINATE, M"
"IDENTIFICATIE"
"MAAIVELD, M+NAP"
"EINDDIEPTE, M+NAP"
3,TXT

iMOD will merge all IPF-files to one large IPF-file and putting these header lines on top of the final IDF-file. In this example the header lines stand for: 1. filetype, 2. legend provided (1=yes, 0=no), 3. amount of IPF-files to be merged, 4.-8. column names, 9. IPF attribute file types with the needed information given in column 3.