A Vertical Electrical Sounding and Self-Potential Methods to Survey for Placement of Potable Water Wells

Water is a precious commodity in most urban and rural areas. Luck of local potable water sources threatens not only thriving but a mere survival of rural communities all over the world. Establishing potable water wells requires a lot of fundings and resources and often cost prohibitive for local governments in South America and Africa. Searching for shallow groundwater require knowledge of subsurface layers and locating intensity and directions of water fluxes, which can be accomplished with geophysical methods of vertical electrical sounding (VES) and self-potential (SP). A method of VES can distinguish differences in electrical resistivity or conductivity at the multiple (10+) layers in soil profiles. These differences reveal the changes in soil texture and structure between water-bearing and waterproof layers, which form a framework for the subsurface water fluxes. The directions and intensities of the fluxes can then be evaluated with the self-potential method. However, conventional equipment for VES and SP is very expensive, bulky and complicated to operate. We tested a simple low-cost handheld device, LandMapper ERM-02, to evaluate layers in the ground with VES method and results were well correlated with drilled profiles in Central TX. Information is provided for the VES array assembly, field measuring procedure and interpretation of sounding results. Previously, device was used in Astrakhan area, Russia for estimation of the groundwater table and salinity layers in the soil profiles. The method of self-potential was used to estimate subsurface water flux directions and intensities through the measured variation in electrical potential on the soil surface and direct potable wells placement in Kiev, Urkaine and Dmitrov, Russia.