Geological and Structural Control of Groundwater Occurrence in parts of Abuja, North-Central Nigeria

Abstract

The study of geological and structural control of groundwater occurrence in parts of Abuja, North-Central Nigeria waass investigated with the aim of providing a model for groundwater occurrence In the area .The study area of lies between latitude 9°07’30”Nto 9°15’00”N and longtitude 7°19’5”E to 7°27’20”E covering Kubwa, Tunga Alhaji, Dutsen Alhaji and Tunga Magaranta area of Abuja. The geological mapping revealed three rock types in the in the area: migrates, schist and granites which were differentiated in two based on texture. Structural analyses of the area indicate NW-SE as the principal joint direction in the area which corresponds to the area underlain by the granites. The vertical electrical sounding method was used to delineate the fracture density and aguifer characteristics of the area. The results of the VES investigation also confirm the NW-SE as the major fracture axis and also confirm to the regional fracture pattern of the area. Thick weathering layer of about 25m to 40m was discovered along the NW-SE direction and the groundwater flows majorly in the same direction which implies that it is structurally controlled and same with the river flow in the area.The geoelectric layers were found in the order of: top layer, weathered layer/fractured zone and fresh basement rock typical of a basement aguifer. The isorsistivity maps taken at various depth further ascertain the dominance of fractures in the NW-SE direction. For good yield in bore holes and wells, it is recommended that groundwater abstraction in the area should concentrate more on the northwestern and southeastern part of the area.