Project

In this part, we develop the strategy for a geophysical field-work campaign carried out along the surface over a target.

Structure

For organisation and storage of all relevant data, we use a structure for the project, guided by the following structure:

- project
  |- dtm (digital elevation models)
  |- coord (coordinate preparation)
  |- dop (digital orthophotos)
  |- geol (geology data)
  |-----------
  |- geodyn5 (data sets in geodyn5 format)
  |- gmt5 (plotting with gmt)
  |- jupyter (processing and plotting with python)
  |- vtk (processed vtk data for paraview)
  |- scan (scanned data)
  |-----------
  |- grav (gravity data processing)
  |- mag (magnetics data processing)
  |- em  (electromagnetics data processing)
  |- ert (ERT data processing)
  |- gpr (GPR data processing)
  |- gravimag (GRAViMAG data processing)
  |-----------
  |- lit (literature)
  |- photos (photos)

Directories

dtm

In this directory, elevation data are kept. Often, they are bought or downloaded from the Landesämtern:

Most of these digital elevation data can be downloaded as xyz ascii data. This format is easily convertible to other formats.

Software needed: gmt5, gdal

Script files (need to be modified):

  • 1_xyz2geodyn5: reformat ascii data to geodyn5 format

  • 2_resample: Resample geodyn5-formatted data, using gmt

  • 3_geodyn2grd: Extract geodyn5-formatted elevation data and save as grd (GMT format) for coordinate extraction.

  • 3_geodyn2tif: Extract geodyn5-formatted elevation data and save as geotiff for a GIS application.

These scripts need to be modified for the project …

coord

Directory for coordinate manipulation. Here, the coordinates for the ERT and GPR profiles are generated, and GRAVITY coordinates are merged.

  • ERT profiles: Collect coordinates in UTM reference system, using a hand-held GNSS unit, or better … It is advisable to mark at least start and end points, and additional points, where the profile turns. The UTM coordinates (easting and northing) for each profile will be processed with python, using createERTCoordElevation (see ERT section).

  • GPR profiles: Collect coordinates in UTM reference system, using a hand-held GNSS unit, or better … It is advisable to mark at least start and end points, and additional points, where the profile turns. The UTM coordinates (easting and northing) for each profile will be processed with python, using createERTCoordElevation (see GPR section).

  • GRAVITY points: While the CG-6 Scintrex gravimeter collects positions of every survey point with its in-build GPS unit, it is better to map the gravity stations with a hand-held GPS unit. As elevation must have cm-accuracy in gravity, we additionally need to level each station. We merge coordinates and leveling data with python, using createGravityCoordElevation (see GRAVIY section).

dop

Directory for Digital orthophotos (DOP), for use in QGIS of python.

geol

Directory for geological information, scanned geological maps, or shapefile exported from the Landesämter.

geodyn5

Directory for all data sets in geodyn5 format.

  • 2Dm*.xy: 2D map data

  • 2Dc*.xz: 2D cross-section data

  • 1Df*.z: 1D core/borehole data

gmt5

Directory for GMT scripts. Needs a working copy of GMT (version 5 or 6).

jupyter

Directory with jupyter notebooks for data processing and plotting.

vtk

Directory for vtk files, used in the paraview 3D viewer.

scan

grav

Gravity data.

  • Original files from CG-6 gravimeter.

  • Tides calculated with eterna34.

Will be imported to GRAViMAG2, processed, and exported as Bouguer anomaly in geodyn5 format.

mag

Magnetics data.

  • Original files from the GEM-T2 magnetometer, downloaded and saved with the GEMLink software.

  • Observatory file for correction (download from INTERMAGET. Choose Niemegk observatory (NGK), the time needed, and as format IAGA-2002.

Will be imported to GRAViMAG2, processed, and exported as total-field anomaly in geodyn5 format.

ert

ERT data. One directory per ERT profile.

  • original files from the Geotom unit (name.wen, name.slm, name.dd, …),

  • converted files in res2dinv format (name.dat),

  • profile coordinates from coord directory (name.profile).

NOTE: The exported Res2DInv files do not contain topography data. You can either add these data manually, or use the python function addERTCoordElevation to add the processed elevation data to the Res2DInv file.

Once the `Res2DInv* file is complete (with topography), it can be inverted with

  • Res2DInv

  • pyGimli oIf oyu use Res2DInv for inversion, the inverted file is saved, and you need to export the inversion.

  • inverted files from Res2DInv inversion (name.inv)

  • exported inversion files from Res2DInv (name.xyz)

Will be merged with script

  • 01_ert2geodyn5: merge name.xyz and name.profile to geodyn5 file format. Uses fortran code ERT_Res2DInv2GEODYN5 from the src directory.

gpr

GPR data. Directory structure follows logic from Reflexw:

  • ASCII: Holds data exported from SIR4000 unit, plus the profile data from coord (name.utm).

Once the gpr data and coordinates are prepared, the program ReflexW is used to process the gpr data. The imported and processed data are stored in the file structure defined by RelfexW:

  • MODEL:

  • LINEDATA:

  • PROCDATA:

  • ROHDATA:

Each final processed gpr line need to be exported (4-colunm ascii format), and is saved in the ASCII directory.

em

gravimag

lit

Directory for literature related to project.

photos

Directory for photos related to project.