What determines the depth of measurement in the Wenner Four-Pin Method?

The depth of measurement in the Wenner Four-Pin Method is determined by the spacing of all rods evenly. This technique involves the placement of four equally spaced electrodes in the ground, which allows for a uniform current distribution and enables accurate measurement of soil resistivity at various depths. The spacing between the outer electrodes directly influences the depth of the measurement because it establishes the radius of the area over which current is flowing and thus defines the zone from which resistivity can be collected.

By maintaining equal spacing between the rods, the Wenner method ensures that the readings taken reflect a more reliable and consistent measure of the soil's electrical properties at different depths. This principle is fundamental for effectively characterizing the soil in cathodic protection assessments and other geophysical studies, making the spacing pivotal to the overall accuracy of the results obtained.