Comparative Analysis of Aquifer Properties in Selected Geologic Terrain in Nigeria

Abstract

Aim of the Study: Two main geologic terrains of basement complex and sedimentary areas were investigated for underground water production capacity by evaluating the aquifer properties. The assessment was done by evaluating 19 boreholes in the two terrains. TK1-TK10 constituted the boreholes from basement area, while AK1-9 constituted boreholes of sedimentary terrain.

Methodology: Pumping rate of the boreholes were crucial to establish the water production capacity from the geologic terrains. Dipper, stopwatch, graduated plastic container, 1 h.p submersible pump, 5.5 KVA generator and field notebook were materials used to collect the field data. Suitable measuring datum of 0.5 m was taken from the ground level for all measurements. SWL was taken and stopwatch was on simultaneously, just as pumping exercise began. The discharge rate was measured then recovery period monitored as pumping stopped.

Findings: Findings of the study revealed Akerebiata sedimentary wells have SWL with 2.8-5.9m, DWL recorded 18.1-28.2m, yield varied between 0.49-0.93L/sec, RDD was measured to be 0.01-0.09m. Specific capacity was calculated to be 42.33-80.35m³/day/m while DWS recorded 0.1-0.2m. Conversely, Tanke wells were pump tested and revealed SWL varied between 6.1 and 8.9m, DWL recorded 48.2-96.2m, yield varied between 0.51-0.72L/sec, RDD was measured to be 0.09-0.18m. Specific capacity was calculated and range from 44.06 to 61.34m³/day/m. DWS recorded for Tanke wells ranges from 0.1 to 0.3m.

Conclusion: The study concluded that the Akerebiata wells are having the potential to produce more underground water than their counterpart i.e. Tanke wells. Recommendation of 0.8-1.3 meters as DWS in the sedimentary terrain and 0.6-1.0 meters in basement complex terrain will allow such wells to last minimum of 10 years before a new well development can be initiated for removal of impurities.