Application of Vertical Electrical Sounding (VES) for the Determination of Water-Bearing Zone in Karaworo, Lokoja Kogi State, Nigeria

Abstract

The importance of water in our various communities and the difficulties faced so far to get good and clean water for both domestic consumption and industrial purposes can never be overemphasized. For these purposes to be accomplished, it is necessary to survey the area of study to know more about the geology of the area, which is characterized by the Lokoja Formation, Patti Formation, and Agbaja Ironstone and the possible reasons why there is a lack of water in the area. The geoelectric survey was conducted at Karaworo with the objective of determining the sedimentary formation's geoelectrical features and analyzing the potential of the groundwater in the study area. The most frequently used type of array for Vertical Electrical Sounding (VES) is the Schlumberger array, which needs a lot of space at both ends to yield deeper subsurface information. The Schlumberger configuration was used for data acquisition. About fifteen (15) VES points were acquired at different locations within the study area. For the different VES positions, the maximum AB/2 is within 100m to 180m. Partial curve matching was used to determine the layer parameters as part of the quantitative interpretation of the VES curves. The IP2WIN software was used in the final data analysis. The depth sounding interpretation revealed subsurface layers which comprises of topsoil/clay with a resistivity range between 1.42 ohm-m to 81.0ohm-m and a thickness of 0.253 m to 70.4 m, lateritic clay with a resistivity range between 01.06ohm-m to 1730 ohm-m and a thickness of 0.236 m to 19.2 m, siltstone with resistivity range between 0.423 ohm-m to 5069 ohm-m and a thickness of 4.09 m to 28 m and sandstone with resistivity range between 0.664 ohm-m to 137 ohm-m with the thickness at infinity. Sandstone constituted the aquiferous zone. In conclusion, different types of curves which include HA-type, H-type, KH-type, QH-type and HAK-type characterize the area and hence it is suggested that boreholes be placed in low resistivity zones and considerable depth and thickness as revealed in VES 4 and VES 8 but those with low resistivity without considerable depth, for example, VES 2, VES 5, VES 6, VES 7, etc. can be developed into a hand dug well.