Pattern and persistence of groundwater level fluctuation in humid tropical regoliths: a case study from Nigeria

This paper is an analytical presentation of the pattern and persistence of groundwater level fluctuation in humid tropical regoliths. Using the Basement Complex in SW Nigeria as a microcosm of the crystalline rock environments in the humid tropics, the groundwater level fluctuation was monitored in three study areas for a number of consecutive years at the sites of observation wells sunk in thick regoliths. The sample data on saturated zone thickness and depth of water in well were analyzed by rigorous but suitable statistical techniques to identify the groundwater level fluctuation pattern and to asses its persistence. The fluctuation pattern in each study area is optimally described by an empirical equation and is perfectly in consonance with the prevailing rainfall regime. Tests for the persistence of the fluctuation pattern reveal that the groundwater regimes in the regoliths of the study areas are almost identical. by reference to the findings of some other research workers elsewhere in the humid tropics it is inferred, subject to verification from further research, that a generally similar groundwater regime prevails in humid tropical regoliths in low-relief deeply weathered landscapes.