Electrical Resistivity Tomography and Vertical Sounding for Groundwater Potentials in Erhoike Community, Delta State, Nigeria

Abstract

This study investigated the Electrical Resistivity Tomography (ERT) A geophysical investigation involving Electrical Resistivity Tomography (ERT) and Vertical Electrical Sounding (VES) for groundwater potentials in Erhoike Community, Delta State, Nigeria, using standard geophysical methods. Six (6) lithologies including the topsoil, dry sand, saturated sand, clayey sand, sandy clay and clay were delineated within the area. The top soil with resistivity and thickness of 547.5 – 8348.6 ohm-m and 0.7 – 1 m respectively represent the first delineated geoelectric layer. This overlies the dry sand having geoelectric parameter of 3.9 – 19.7 m and 761.4 – 8248.6 ohm-m respectively. The dry sand layer underlain by the saturated sand having resistivity ranging from 114.3 – 1380.6 ohm-m. The resistivity of the clayey sand oscillates between 47.6 – 85.3 ohm-m. This layer represents the last layers at the locations where it was delineated, as such the thickness could not be estimated. The clay layer underlies sandy clay in places while in other cases, it succeeds the topsoil. The resistivity and thickness of the clay layer were 11.4 – 48.9 ohm-m and 25.8 – 56.1 m respectively. The sandy clay was found to have resistivity of 50.6 – 115.3 ohm-m and thickness of 2.9 – 8.8 m. The results of the study showed that the saturated sand layer represents the aquiferous layer within the area where groundwater can be tapped for the community. The thickness of this layer is found to be more than 58.2 m which is quite significant for groundwater development. The study concluded that there is abundance of groundwater accumulation beneath the area. It further reinforced the applicability of combined ERT and VES in groundwater potential mapping in an area underlain by similar geology.

Keywords

• geophysical techniques;
• electrical resistivity tomography;
• vertical electrical sounding