GROUNDWATER TRANSMISSIVITY FROM ELECTRICAL RESISTIVITY

Groundwater flow is a major determinant of early settlement patterns as nearness to springs, streams and rivers are seriously put into consideration in making settlement choices. Groundwater is not common occurrence in parts of Delta North Senatorial District with remarkable high altitude. However, at Ibusa there are several groundwater flow sources which suggest that Ibusa is a mountainous plain surrounded by water bearing valleys. Most of these sources have extinct in recent time due to neglect and other human activities. Ironically, drilling successful borehole has been a major problem in Ibusa. There is therefore the need to investigate these sources, proffer geophysical and geological explanations to their occurrence, existence and delineate their transmissivity and aquifer sustainability. Hence, this study was made using Electrical Resistivity Technique (ERT) and computer iteration to provide desired empirical analysis and interpretations. Four curve types HKHA, AKQ, KHQ and AHQ with six layers were deduced generally. The top layer consists of thick lateric soil to a depth of about 1.4 metres followed by compact laterite of about 10 metres thick. The third consists of sandy clay formation to 20 – 30 metres. This medium houses steams in some valleys and springs in rock faults. The fourth layer is a mix of clay and shale to about 40 metres. On the North East axis, a rock shield is encountered as the fifth layer at about 50 metres. It engulfs thick layers of fine sand, medium grain sand and coarse grain sand t