Integrated Geological, Hydrogeological And Geophyysical Assessment of Groundwater Potential in Tuun-Fulani Area of Minna, North-Central Nigeria

Abstract

Groundwater is the major source of potable water for human use. An integrated approach of geological, hydrogeological and geophysical techniques has been used to investigate the potential of groundwater in part of Minna, north-central Nigeria. Granite and granite-gneiss are the two dominant rock types in the study area. Structurally, the principal joint direction in the area trend is NW-SE, which also controls the groundwater flow mechanism. A total of 50 vertical Electrical Sounding (VES) stations were established. The major curve types encountered in the area are H, HA, A and KA. Three major lithologic clay units were identified from the geoelectric sections; the unsaturated top soil which is mainly lateritic clay, the weathered/fractured layer and the fresh basement layer. The lateritic clay as a topmost layer is a thin highly resistive layer with resistivity ranged between 41.0 Ω m to 99.0 Ω m and 0.9 m to 3.2 m. The weathered basement rocks has resistivity value of 23 Ω m to 1820 Ω m and a thickness range of 1.6 m to 26.0 m. The fresh basement rock is characterized by high resistivity values and exceeds 1000 Ω m. Static water level (SWL) measurement were collected from 80 hand dug well in the area and the values used to plot the groundwater low map. The thickness of layer extends to an infinite depth. Isoressistivity and isopach maps were generated from the geoelectric parameters of the subsurface and used to characterize he subsurface. The results revealed that the southern portion of the study area has higher groundwater potential and the display of lower resistivity value and deeper overburden thickness validates the findings. The rosset diagram confirms groundwater flow direction of NW-SE, which conforms to the regional fractures density of the area. Hand dug wells in the area can be terminated within the regoliths/weathered basement units in the area which lies within the depth range of 2.5 m to 12 m while boreholes in the area should be terminated at depth range 60 m to100 m.