THE USE OF ELECTRO-MAGNETIC (EM) METHOD IN GROUNDWATER PROSPECTING IN A BASEMENT AREA OF SABO, KADUNA STATE

Modern Technology in geophysical prospecting (Electromagnetic Method (EM) has provided instrument with better resolution, relatively high speed of operation and low manpower% requirements. Successes have greatly been achieved in water supply schemes in basement complex of this area. Use of electromagnetic method especially in groundwater prospecting in basement terrains is making process of bore-holes drilling operation successful, precise and cost effective. Electro-magnetic (EM) survey of part of the basement was carried out in the Sabo area, Kaduna, Kaduna State Basement complex terrain. An orientation survey was carried out and five profile lines earmarked and pegged at 200m spacing in between each profile line. The very low frequency VLF (Genomic EM16) method was used for the survey at a spacing (a = 20m), making a total numbers of two hundred and five VLF station points. The data from the electro-magnetic mapping were processed by graphical and contouring methods. The results from the electromagnetic responses gave an overall idea about the lateral variation in conductivity and broad lithological differentiation using the EM anomaly amplitudes in the areas where the basement rocks are not concealed is considered feasible. A closer study on the EM anomaly contour maps delineated zones of fracture (faults which are zones of interest in terms of water prospecting and even mineralization. The study examines the role performed by electromagnetic technique as a general reconnaissance geophysical survey instrument for aquifers in die sabo area in the south of Kaduna State. The results obtained are being used for further detailed investigations using other geophysical methods’ such as magnetic, vertical electrical sounding and horizontal electrical profiling.