Hydrogeophysical Evaluation of Groundwater Potential in Federal Housing Estate Lugbe, Abuja, Nigeria using Electrical Resistivity Method

Abstract

Inadequate water supply remains one of the challenges facing residents of Federal Housing Estate, Lugbe, Abuja, Nigeria. The groundwater potential of the area was investigated using vertical electrical sounding (VES) method. A total of 40 VES points were used for the investigation using Schlumberger array and data obtained were analysed using curve matching and computer iteration techniques. The data revealed both a 3-layer (H-Curve) and a 4-layer (HA-Curve) for the area. In the 3-layer system, the apparent resistivity for the first layer ranged from 63 Ωm to 658 Ωm with a corresponding thickness of 0.8 to 2.1 m. The second layer has an apparent resistivity varying from 29 to 726 Ωm with a corresponding thickness range of 3.0 to 21.7m while the third layer has resistivity values ranging from 96 to 6769 Ωm to an infinite depth. For the four layered model curves, the first layers resistivity ranged from 37 to 1087 Ωm, with a corresponding thickness of 0.5 to 2.4 m. The resistivity of the second layers ranged between 28 to 2453 Ωm with a corresponding thickness of 1.4 to 15.3 m. The resistivity of the third layer ranged from 25 to 2441 Ωm with a corresponding thickness range of 7.3 to 37.3 m respectively. The fourth layer has a resistivity value ranging from 69 to 6820 Ωm and an infinite depth. An integration of isopach and isoresistivity maps for both 3 and 4 layer model curves indicates that the northern parts of the study area have low apparent resistivity values and thick overburden which implies good groundwater potential while the southern portion has higher resistivity values and shallow overburden, an indication of poor groundwater potential. Future boreholes in the area should reach an effective depth of 45 to 65 m and the borehole be supervised by a certified hydrogeologist for optimum groundwater yields. Pumping tests should be carried out to ascertain the size and type of submersible pump to install.