Empirical equations of groundwater recharge patterns

Abstract

This paper emanates from attempts at fitting empirical equations to describe the patterns of groundwater recharge in the regolith of the Middle Osun Valley in the Nigerian Basement Complex. Equations of both the temporal and spatial patterns of groundwater recharge were derived empirically by analysing sample data on saturated zone thickness using a least-squares curvilinear regression technique. The temporal pattern for the study period conforms with the prevailing rainfall regime and is optimally described by fourth-degree polynomial regression equations. The spatial pattern is optimally described by quadratic equations and suggests that an almost uniformly thick annual groundwater recharge zone of about 2.4 m overlies the gross spatial distribution of saturated zone thickness from the major river channel to the major water divide. The quantitative methodology of this study is universally applicable and could greatly facilitate direct calculation of groundwater recharge and rainfall-recharge correlation if reliable information about relevant parameters of Basement Complex regolith aquifers is available. © 1986 Taylor & Francis Group, LLC.