Delineation of Aquifer Storage Capacity in Response to Regional Groundwater Development

Abstract

Developing aquifers as part of sustainability efforts towards groundwater development is a tactical approach to meeting water demand and management objectives. Delineation of aquifer storage capacity (ASC) and longitudinal conductance (S_L) is a good approach in an attempt to increase water supply. Due to site-specific needs and demands, ASC and S_L play an all-important role in regional groundwater development and sustainability. This study applied Schlumberger and 2D electrical resistivity image (ERI) to determine the regional aquifer thickness in an attempt to assess the strength of ASC and also evaluation of a local S_L that can also be applicable regional scales using fifteen (15) VES points with one orthogonal profile of 2D ERI. The study shows that the layer resistivity values of the regional aquifer range from 39.9 Ωm – 105 Ωm, while the aquifer layer thickness values spread from 15 m – 44 m and the overburden thickness overlays the aquifer unit extends from 5 m to 10 m. The deeper aquifer zones were delineated within the depth of 30 m – 44 m, and the zones are considered to be suitable for groundwater development. The weathered/fractured basemen, which constitute the regional aquifer are delineated. The weathered layer with appreciably low resistivity values with thick aquifer regolith has also been identified as most suitable for borehole siting. The weathered/fractured encountered within thick aquifer regolith indicates a high storage capacity and positive groundwater development. The longitudinal conductance, SL and transverse resistance, RT estimated from aquifer parameters vary between 0.21 Ω-1-0.85 Ω-1 and 1695 Ωm2-3124Ωm2 respectively. The SL values show that that study area falls within moderate (0.20 Ω-1-0.69 Ω-1) and good (0.7 Ω-1-0.49 Ω-1) ASC, which invariably improved the regional aquifer recovery processing.