Understand the ground.
Plan with evidence.

Vertical Electrical Sounding (VES)

ZEDOPS undertakes geophysical surveys and interpretation using VES to support groundwater exploration. The method investigates how electrical resistivity varies beneath a sounding location, helping assess possible subsurface layers before drilling.

How the methodology works

1. Review the site. Consider local geology, access, terrain and available information from nearby boreholes.
2. Collect resistivity readings. Place current and potential electrodes in a suitable arrangement, such as a Schlumberger array. Increase electrode spacing around the sounding point, recording current and potential differences to calculate apparent resistivity.
3. Check and interpret the data. Review readings for consistency and model sounding curves to estimate layer resistivities and thicknesses. Compare the interpretation with geological and borehole information where available.
4. Guide the drilling plan. Assess potential water-bearing zones and use the combined evidence to recommend a drilling location and an indicative target-depth range, subject to site findings.

What the findings mean

A VES interpretation is a model, not a direct image of an aquifer. Different ground conditions can produce similar responses; low resistivity alone does not prove fresh groundwater. The method is most useful when its assumptions about layering are appropriate to the site.

Drilling observations, pump testing and laboratory water analysis are separate steps. VES does not guarantee a successful borehole, a particular yield or safe drinking water.

Discuss your survey

Share the project location, intended water use and any existing survey or borehole records. We can then discuss a suitable scope and interpretation requirements.

Technical reading

USGS: Direct-current vertical electrical-resistivity soundings describes Schlumberger-array measurements and inverse modelling. USGS: Application of surface geophysics to groundwater investigations provides further background. These references explain the method and do not imply endorsement of ZEDOPS.