Time-Domain Electromagnetic Sounding for Deep Aquifer Investigation in Katsina State, North West Nigeria

Katsina State in North West Nigeria experiences recurrent drought cycles that deplete shallow groundwater sources, necessitating exploration of deeper aquifer systems capable of sustained supply during dry seasons. This study applies time-domain electromagnetic sounding to investigate deep aquifer potential in Dutsin-Ma and Safana Local Government Areas where shallow boreholes have repeatedly failed. TDEM measurements were acquired at 12 sounding stations using a central loop configuration with a 50 by 50 metre transmitter loop. Data were collected at logarithmically spaced time gates from 0.04 to 2.5 milliseconds to sample depths from near surface to approximately 200 metres. Observed transient decay data were converted to apparent resistivity and inverted using a layered earth model algorithm to produce one-dimensional resistivity depth profiles. A pronounced low-resistivity zone, interpreted as a saturated sandstone aquifer, is identified between depths of 80 and 130 metres at four of the sounding stations located along a NE-SW trending structural corridor. The estimated water-bearing layer thickness and resistivity contrast suggest aquifer productivity comparable to productive deep sandstone wells elsewhere in the Sokoto-Rima Basin. Two priority drilling sites are recommended for exploratory boreholes to verify the TDEM predictions. The study provides foundational data for a sustainable water supply programme targeting deep aquifers in drought-prone communities. Keywords: TDEM, deep aquifer, Katsina State, electromagnetic sounding, drought