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

The depth of measurement in the Wenner Four-Pin Method is primarily determined by the spacing of all rods evenly. This method utilizes four equally spaced electrodes inserted into the ground, and the distances between these electrodes directly influence the current distribution and the resulting measurements obtained from the test.

When the rods are spaced evenly, it creates a consistent and controlled condition for measuring resistivity. This uniform spacing allows for a predictable depth of penetration of the electrical current into the soil or material being tested, which is crucial for accurately assessing the subsurface resistivity. Additionally, the geometry of the setup dictates how deep into the ground the measurements will reflect conditions, as the current path diverges from the outer electrodes to the inner electrodes.

In contrast, factors such as the off-centerness of the rods or offsets between inner and outer rods would complicate the interpretation of results and could introduce inconsistencies in the measurement. While operator input regarding measurements and adjustments can aid the process, the fundamental relationship between the spacing of the electrodes and the resultant depth of measurement is the key factor in the effectiveness of the Wenner Four-Pin Method.