Geoelectrical Characterization of Coastal Aquifers in Agbado-Ijaye, Lagos, Southwestern Nigeria; Implications for Groundwater Resources Sustainability

Abstract

Water is a natural resource; its availability depends on climatic and geological conditions, and it is invariably controlled by human activities. Agbado-Ijaye lies within a coastal area, where local communities have been facing incessant water shortages, especially during the dry season. This study investigated the groundwater-bearing geological unit(s) using hydrogeophysical techniques in the coastal environment. The electrical resistivity technique, involving vertical electrical sounding (VES) and two-dimensional (2D) electrical resistivity imaging via Wenner array electrode configuration, was used to characterize the geoelectric distribution. Twenty VES stations were investigated and current electrodes (AB/2 m) spacing expanded from 1–200 m; four 2D electrical resistivity imaging traverses having a length of 200 m each and interelectrode spacing of 10 m (level 1) to 60 m (level 6) was adopted. Four geoelectric units were delineated, namely: topsoil (15–251 Ωm), clayey (28–100 Ωm), clayey sand (125–190 Ωm) and sandy (205–876 Ωm) with thicknesses ranging from 0.7–1.3 m, 4.1–19.0 m, 2.6–15.6 m and undefined depth, respectively. The 2D imaging sections also detected similar geoelectric layers, corroborating the VES-derived sections. The inverted sections delineated two different aquifers: the shallower low-yield aquifer comprising sandy clay/clayey sand units with a maximum depth of about 5.5 m. This layer is adjudged to be the continental plain sand of the Benin Formation. The deeper high-yield aquifer with a maximum depth of 30.4 m is a beach sand unit that belongs to the Tertiary Alluvium of the Dahomey Basin. The study showed that hydrogeophysical investigation is vital in exploring, developing, and managing coastal groundwater resources.

Groundwater Prediction Analysis for Sustainable Development in Okeigbo, Southwestern Nigeria: A GIS supported AHP Approach

“…It is often possible to make qualitative hydrogeologic deductions from curve types, thus the area is generally made of high resistive topsoil, underlain by high conductive weathered layer, and basement rock. The preponderant of H curve type is usually a common occurrence in the basement complex of southwestern Nigeria, as similar studies such as Oyeyemi et al (2023) A.1, revealed three to five geoelectric layers, consisting of topsoil, subsoil, weathered layer, partly weathered/fractured basement, and fresh basement. This type of geological succession is the most common in the basement complex (Olorunfemi & Olorunniwo, 1985;Oyegoke et al, 2020;Mogaji et al, 2011;Oloruntola & Adeyemi, 2014;Olatokunbo-Ojo & Akintorinwa, 2016;Bayewu et al, 2018;Aina et al, 2019;Akanbi, 2017;Adagunodo et al, 2018;Abdullahi et al, 2015;Falowo, 2022b;Akintorinwa, 2015).…”

A Hydrogeological Conceptual Model Refines the Behavior of a Mediterranean Coastal Aquifer System: A Key to Sustainable Groundwater Management (Grombalia, NE Tunisia)

“…In the face of escalating global water concerns, the urgency to safeguard aquifers becomes more pressing [58]. The depletion of these vital resources carries substantial risks for ecosystems and the agriculture and industrial sectors, accentuating the imperative for the use of sustainable water management practices [58,59]. The findings of this 3D hydrogeological conceptual model act as a foundational resource for guiding the sustainable management of groundwater resources within the Grombalia aquifer system.…”

Coastal vulnerability assessment using electrical resistivity tomography in Padang Betuah, Central Bengkulu

“…The geophysical method that can describe the subsurface rock structure in 2D and 3D in the coastal areas of Central Bengkulu is the geoelectric method. This method has been widely used in coastal area studies [15]- [19]. Electrical resistivity tomography (ERT) is a geoelectric method one of the geophysical methods that can determine the subsurface geological conditions based on the electrical properties of the constituent rocks [20].…”