DETERMINATION OF SEASONAL VARIATIONS OF AQUIFER DEPTH IN A PART OF BASEMENT COMPLEX OF ILORIN METROPOLIS

S. Olatunji^1* and L. M. Johnson²

¹ Department of Physics, University of Ilorin, Ilorin, Nigeria

² Department of Geology and Mineral Science, University of Ilorin, Ilorin, Nigeria.

E-mail: sam61ng@gmail.com.,mobolajijay@gmail.com

ABSTRACT

Depth to water table was monitored for six consecutive months by direct measurement in nine hand-dug wells within Ilorin metropolis, lying within the basement complex of north central Nigeria. Weekly time series of rainfall and well water level were cross-correlated to investigate seasonal variations in groundwater-level response times, based on periods of 6-month duration. The aims are to monitor the fluctuation of the aquifer recharge, determine the drying rate, detect possible seepage in the studied wells and to analyse geohydrological information. The result shows that in two of the wells some volumes of water are leaking fast at the rate of 0.333m/week and 0.295 m/week to the host rock probably through underground connected pores. This could imply that the wells are seated on fractured and or porous basement. Further with exception of well 2, all other wells show appreciable response to the rainfall. This implies that rainfall is a major recharge source to the aquifer in the study area.

Key words: Well, Aquifer, Aquiclude, Drying-rate, Recharge, Borehole.