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The technique and procedure described here can be performed with any model of Landmapper (older models ERM-01 and -02 or new ERM-03 and -04). LandMapper ERM-03
Manual VES” cable set made to measure 16 layers of topsoil down to approximately 9 m. The worksheets for pre-set electrode spacings in such cable re-calculating measured resistivities to apparent resistivity, see this Google Drive public folder for downloads:  1D-VES.

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 and video below.

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 the second page in the Excel workbook will re-calculate ER automatically and plot VES profile.
  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 marks (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 the 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 need to be multiplied on appropriate K-coefficients. Use tables below or input in Excel file to carry out auto-calculations.

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

AB MN The measurement from deep to shallow
distances, m m #

AB/2, m

K-set

K-taken

 ER-1 ER-2 ER-3 ER-4
[A1B1] = 28

2.0

1

14.0

K0=1

1

10.41
[A2B2] = 24

2.0

2

12.0

K0=1

1

27.47
[A3B3] = 20

2.0

3

10.0

K0=1

1

102.8
[A4B4] = 18

2.0

4

9.0

K0=1

1

15.75
[A5B5] = 16

2.0

5

8.0

K0=1

1

13.49
[A6B6] = 14

2.0

6

7.0

K0=1

1

10.26
[A7B7] = 12

2.0

7

6.0

K0=1

1

21.28
[A8B8] = 10

1.0

8

5.0

K0=1

1

30.07
[A9B9] = 9

1.0

9

4.5

K0=1

1

12.29
[A10B10] = 8

1.0

10

4.0

K0=1

1

13.73
[A11B11] = 7

1.0

11

3.5

K0=1

1

15.37
[A12B12] = 6

1.0

12

3.0

K0=1

1

62.18
[A13B13] = 5

1.0

13

2.5

K0=1

1

16.02
[A14B14] = 4

1.0

14

2.0

K0=1

1

26.04
[A15B15] = 3

1.0

15

1.5

K0=1

1

18.18
[A16B16] = 2

1.0

16

1.0

K0=1

1

18.18

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.

AB MN Measurement from deep to shallow Recalculate ER for VES interpretation
distances, m m # AB/2, m K-multiply K-taken ER-1
[A1B1] = 28 2.0 1 14.0 306.3 1 3188.6
[A2B2] = 24 2.0 2 12.0 224.6 1 6170.4
[A3B3] = 20 2.0 3 10.0 155.5 1 15986
[A4B4] = 18 2.0 4 9.0 125.7 1 1979.2
[A5B5] = 16 2.0 5 8.0 99.0 1 1335
[A6B6] = 14 2.0 6 7.0 75.4 1 773.59
[A7B7] = 12 2.0 7 6.0 55.0 1 1169.9
[A8B8] = 10 1.0 8 5.0 77.8 1 2338.1
[A9B9] = 9 1.0 9 4.5 62.8 1 772.21
[A10B10] = 8 1.0 10 4.0 49.5 1 679.36
[A11B11] = 7 1.0 11 3.5 37.7 1 579.44
[A12B12] = 6 1.0 12 3.0 27.5 1 1709.3
[A13B13] = 5 1.0 13 2.5 18.8 1 301.97
[A14B14] = 4 1.0 14 2.0 11.8 1 306.78
[A15B15] = 3 1.0 15 1.5 6.3 1 114.23
[A16B16] = 2 1.0 16 1.0 2.4 1 42.836

sample VES profile in pseudo-depths

After automatic recalculation of VES profile in the table above, an Excel file shows 1D profile of electrical resistivity in “pseudo-depths”. To interpret VES profile to exact depths and layers you may use a number of free 1D resistivity interpretation programs (download the whole folders and run from your PC!):

  • iVEZ  (our in-house “soil” VES semi-automatic interpretation software, developed in 1983)
  • RES1DINV – (1D VES freeware by Dr. Loke, we recommend this especially if you plan to link several 1D VES to 2D tomography with RES2DINV) 

Good Field Practice: If you wish to rely on stored ER data, make sure to set up a 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 the actual field session, so you don’t get confused about which data are those!

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