Electrical Techniques
Spontaneous (Self) Potential
Detail
The spontaneous potential (SP) method is a passive electrical technique that involves measurement of naturally occurring ground potentials. These can be generated from a number of different sources although all require the presence of groundwater to some degree. The two main sources of interest in environmental and engineering studies are streaming potentials, due to movement of water through porous subsurface materials, and diffusion potentials resulting from differing concentrations of electrolytes within the groundwater.
SP measurements are made using a pair of non-polarising electrodes. These normally comprising a pot containing a copper electrode immersed in a saturated copper sulphate solution. A porous base to the pot enables the electrolyte to percolate out and make contact with the ground. The potential difference between the two pots is measured using a high impedance voltmeter.
Common applications for SP measurements include assessing seepage from dams and embankments, fluid migration pathways in landfills, mapping coal mine fires and for the study of drainage structures, shafts, tunnels and sinkholes.
