Comparative Analysis of Empirical Formulae Used in Groundwater Recharge in Ogun – Oshun River Basins

Quantification of the rate of natural groundwater recharge is a pre-requisite for efficient groundwater resource management. It is particularly important in regions with large demands for groundwater supplies, where such resources are the key to economic development. However, the rate of aquifer recharge is one of the most difficult factors to measure in the evaluation of groundwater resources. Estimation of recharge, by whatever method, is normally subject to large uncertainties and errors. In this paper, an attempt has been made to derive groundwater recharge from rainfall in ogun-oshun river basin using three empirical formulae and they include modified chaturvedi formula (1936) and Krishna Rao (1970) in Kumar, (2009); Kumar and Seethapathi (2002). Results from these three empirical formulae were compared using line graph, inter-item correlation and one way analysis of variance (ANOVA). A correlation coefficient of the range of 0.99-1.0 exist between each formula, and the rejection the null hypothesis that the means of the three formulae are not different from each other leading to the conclusion that any of the formula can be used for recharge estimations.