Integrated geoelectrical and structural studies for groundwater investigation in parts of Abuja, North Central Nigeria

Abstract

Abuja, the capital city of Nigeria, West Africa, is underlain by Precambrian basement rocks consisting mainly of porphyroblastic gneisses, granitic‐gneisses, migmatitic gneisses, amphibolites, Pan‐African granites and undifferentiated schists. The geology of Abuja, therefore, makes the groundwater conditions in the area very unpredictable. Geophysical surveys were carried out at 12 locations within and around the Gosa area and the results integrated with 88 lineament (fractures) extracted from hill‐shaded Shuttle Radar Topography Mission (SRTM) data. The dominant fracture trend for the area is NNE–SSW and N–S, which corresponds to the Pan‐African trends in the basement complex of Nigeria. It is observed that in the Gosa area, whereas fractures exist, they do not possess sufficient interconnectivity; this may have adversely affected the permeability of the fractured zone, resulting in the incidence of dry wells in the area. Moreover, evidence from interpreted two‐dimensional (2D) geoelectric sections reveals that in some parts of Abuja, the weathered overburden is not thick enough to support sufficient yield for a viable borehole. Interconnected fractures therefore become the desirable structural feature capable of improving the aquifer potential. This study demonstrates the usefulness of integrating conventional vertical electrical sounding (VES) surveys with structural data derived from enhanced SRTM imagery in a hydrologically complicated terrain.

Tectonic and radioactivity impacts of238U on groundwater-based drinking water at Gosa and Lugbe areas of Abuja, North Central Nigeria

“…The activity concentration of 238 U in Gosa borehole may not have been in + VI (uranyl oxidation state) due to non-interconnectivity of fractures that would have allowed + IV (uranous state) to oxidize to + VI by enhancing the activity level in the borehole sample at Gosa. The lower activity level found at Gosa bore-hole may have been affected by the geology of the area such as insufficient fractures, joints and fissures that creates favourable condition for water-rock interaction and thorough mineral contacts with groundwater system [25]. Table 2 summarizes the concentrations of 238 U in groundwater in the study area and compared to other works published elsewhere [26][27][28][29][30][31][32].…”