Electromagnetic Profiling for Groundwater in Precambrian Basement Complex Areas of Nigeria

Ground electromagnetic profiling, using a Geonics EM34-3 instrument, has been employed to identify areas of high conductivity in a Precambrian basement complex terrain of Nigeria.

Field examples, conducted as part of a rural water supply programme, are presented. They indicate that the apparent conductivities are generally lower than about 60 mmho m⁻¹. Subsequent borehole drilling suggests a good correlation between high EM34 anomalies, deep weathering and high well yield (> 1 1 s⁻¹). On the other hand, boreholes sited on conductivity lows penetrated a thinner regolith with relatively lower yields.