Geophysical investigation of effects of topographic complexities on groundwater potential in Ibusa, Delta State Nigeria

摘要

Ibusa is situated a few kilometres from the River Niger near Delta State capital, Asaba. .Despite its nearness to the course of River Niger, it is positioned on a cliff which makes the acquisition of groundwater a serious problem for the inhabitants. It marks a transition point from the river bank to the hinterland and between geological formations. It is therefore, necessary to carry out geophysical survey within and around Ogboli, Ezukwu and Achala in Ibusa to determine the topographic complexities and their effects. Thus, ten VES soundings were made using Schlumberger array with a sensitive SAS 1000 terrameter. The results show that virtually all sites in the study area exhibit A – type curve. They also indicate that while Ogboli and Ezukwu villages have typically deep aquifers enclaved by deep rooted rocks, neighbouring Achala village is a low land zone with shallow aquifer. In addition Ogboli and Ezuikwu villages consist of thick lateritic top soil to about 10 m, remarkable weathered rocks of high iron content at shallow depths of 15 – 18 m and a thick formation of hard granite at far depth. False aquifers exist at shallow depths of 30 – 40 m while viable aquifer is at 80 – 110 m. On the other hand, Achala possess loose top soil to considerable depth followed by a thin layer of lateritic soil, a layer of medium to gravely sand and viable aquifer at about 30 – 40 m