In electrical surveying, electrodes inject current into the ground and measure voltage differences at the surface. Moving the electrodes produces profiles used to estimate how resistivity changes with depth. The result is a model calculated from measurements, not a direct picture of the subsurface.
Resistivity depends on several factors: rock type, porosity, water content, salinity and clay. Different combinations of materials can produce similar responses. A conductive zone may relate to water, clay or mineralised water; it does not prove on its own that a borehole will be productive.
Survey design, electrode contact and quality checks all affect the measurements. To reduce ambiguity, results are compared with local geology, borehole records and other available methods. The aim is to target further investigation more carefully, then check the interpretation in the field.
