Evaluation of groundwater potential using aquifer characteristics on parts of Boki Area, South- Eastern Nigeria

Abstract

Vertical Electrical Sounding (VES) and pumping test (constant discharge and recovery test) was carried out in parts of Boki Local Government Area to evaluate the groundwater potential, using aquifer characteristics of the study area. Sixteen (16) VES point was employed for this study using the Schlumberger array, with a maximum spread of 400- 600m. The stimulated result from the field data shows 3-5 layers resistivity model with the following curve types A, AK, KH, KHA, QH, QHA and QHK. The geoelectric properties include resistivity of the various layers ranging from 33.58 - 2.29 x 105Ώm, thickness from 0.2 - 50.2m, depth to basement varies from 2.99 - 74.60m across the study area. The litho logs show a top layer comprising of laterite, gravel/gravelly sand and intercalations of siltstones, the layers underneath are made-up of clay, weathered basement containing migmatites and gneisses, fractured and unfractured basement are made up of granitic and metamorphic rocks. The weathered and fractured layers constitute the aquiferous layers in the study area. Hydraulic parameters show transmissivity (T) range of 4.1x 10-5 - 1.92 x 10-1 m 2/day, specific capacity (SC) ranges from 2.09-21.42m2 /day, hydraulic conductivity (K) varies from 2.6 x 10-5 - 3.0 x10-3m/day and mean static water level (SWL) of 7.39m. Iso resistivity map of saprolite, fractured basement map, isopach map and the transmissivity map show that the studied area falls within the low-moderate groundwater potential zone.