The Use of Electrical Resistivity Survey for Groundwater Exploration in Ga West Municipality, Greater Accra Region, Ghana

In Ga West Municipal Assembly of Ghana, lack of potable water in both urban and rural communities necessitated the need for groundwater exploration in 11 communities. For this purpose, 1-dimensional electrical resistivity profiling and vertical electrical sounding were carried out in these communities using ABEM Terrameter SAS 300C.The Schlumberger electrode array was used for both electrical resistivity profiling and vertical electrical sounding.While the electrical resistivity profiling led to the identification of 31 anomalous pointsfor vertical electrical sounding, the modeled results of the 31 anomalous point led to identification of 3, 4 and 5-layer subsurface structures characterized by A, H, K, AA, KH, QH and HKH- types resistivity curves. The H-type is the most dominant and occurred mostly in areas underlain by granite of the Birimian Granitites whileK-type is associated withOfankor Market, underlain by Togo Structural Units.Analyzed results showed that apparent resistivity for first layer values varied from 38.8 ? m at Ebenezer (A 4) to 1624.6 ? m at Dedeiman (A 80); intermediate layers had apparent resistivities that changed from 10.0 ? m (A 35, Adom) to 2494.4 ? m (A 80, Dedeiman) while bedrock apparent resistivity values varied from 50.4 ? m (A 28, Dedeiman) to 1613.4 ? m (A 43, Ntafrafra). Thickness of intermediate layersexceeding 9.1 m indicate conductive zone for groundwater occurrence while low(50.5 ? m)to moderate (813.1 ? m)bedrock apparent resistivities indicates thepresence of fracture systems within the bedrock and therefore such points were considered suitable for exploitation. While all anomalous points identified at Adom, Ofankor market and Dedeiman are suitable for the construction of tube wells, other suitable points that can be considered for construction of boreholes are B 53 at Saapeiman, B 15 at Ayikai Dobro, either A 30 or A 55 at Tetteh Asofaha, A 120 at Gatsikope, B 25 at Ntafrafra, B 62 at Adjeiman Kpalafia, A 18 at Ebenezer, and A 36 at Atsiato. Anomalous points that may not support the exploitation of groundwater include A 4 at Ebenezer and A 19 at Atsiato, A 169 at Gatsikope, A 59 at Ayikai Dobro, A 30 at Ntafrafra, and A 43 at AdjeimanKpalafia. Thus, there exist at least a point in each community suitable for the construction of boreholes.