1D Vertical Electrical Sounding (VES) with LandMapper Procedure

The technique and procedure described here can be performed with LandMapper ERM-01 or ERM-02 (set in resistivity mode). The electrode spacings provided in this example are identical to Landviser's supplied "big manual VES" cable set made to measure 16 layers of topsoil down to approximately 9 m. The worksheet for pre-set electrode spacings in such cable re-calculating measured resistivities to 1D VES profile can be downloaded as Manual 1D VES workbook (MS Excel format).

Other electrode spacings are possible for custom-made cable arrays to reach deeper profiles. For example, we developed and tested with LandMapper a 60m-long cable, measuring down to ~ 20 m for one custom hydrology project.

This manual VES technique is most convenient to use with three people. Follow step-by-step instructions below. If you need further help, do not hesitate to contact Landviser, LLC @ +1-609-412-0555 or info@landviser.com. Register on our site and download 7 related publications and software! Manual 1D VES workbook

1. On your site establish the center location for the VES profile. It is a center point between M2 and N2 in the diagram above. Here the person with LandMapper will stay and conduct measurements.
2. Send two persons outward in a straight line from the center to unwind both red wires from the probe up to 14 m mark (last electrode) and insert electrodes in soil => A1 and B1.
3. Measuring person grounds central black M1N1 electrodes at MN/2=1.0 m (green label, black wires). Connect black wires (MN) to MN- terminals of LandMapper.
4. Connect red wires (AB) to AB- terminals of LandMapper.
5. Take ER-reading at K0=1 and AB electrodes at 14 m.
6. Move A and B electrodes to 12 m marks at both sides - take ER-reading.
7. Continue  until AB/2=6.0 m.
8. Move MN electrodes to 0.5 m mark (black wire, green label) and AB to 5.0 m mark.
9. Continue taken measurements until last AB/2=1.0 m. It is also previous location of M1N1 electrodes for steps 3-7.
10. Field ER-readings can be stored in LandMapper memory or recorded manually.
11. The recorded ER-values needs to be multiplied on appropriate K-coefficients. Use tables below or input in Excel file to carry out auto-calculations.

Note: if ER values measured on deep AB/2 (#1-5) are too small, switch to K1=10, or even K2=100 (99.99), don't forget to record which K-taken you used in the table,  then the table on second page in the Excel workbook will re-calculate ER automatically and plot VES profile.

Field data recording table. You can print this table from the website or download  Manual 1D VES workbook Excel fileas there is a table already pre-formatted to fit on Landscape page.

Instead of writing ER values on the paper in the provided table, you can store ER in LandMapper's memory. You still need to keep track of what cell # starts new VES profile and which K values had you used (those K1-K9 are stored indefinitely, but don't change K in the middle of field trip).

Recalculation table. This table automatically recalculates field ER measurements taken in the table above (in Excel file). Here on website it just shows values of K-geometric coefficient (K-multiply) for pre-set distances among electrodes using formulas for Schlumberger and Wenner arrays.

After automatic recalculation of VES profile in a table above, Excel file shows 1D profile of electical resistivity in "pseudo-depths". To interprete VES profile to exact depths and layers you may use a number of free 1D resistivity interpetation programs: iVES - SETUP-VES1D.zip, RES1DINV - r1d.zip, IP-Win etc.; most of which can be downloaded from this website.

Good Field Practice: If you wish to relay on stored ER data, make sure to set up data connection to your computer BEFORE you head to the field! You can store some mock data and do download and memory clean up before you go out and start collecting real data! Also clean up ERM-01 memory from all mock data before actual field session, so you don’t get confused which data are those!

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