Aquifer characterization using geophysical and pumping test data in Kericho, Kenya

Abstract

The exploration of groundwater resources has considerable potential for boosting water supplies in Kericho County, Kenya. However, it is underused due to limited knowledge caused by lack of adequate research in this field. As a way to fill this gap, this study aimed to characterize hydraulic and hydrogeological parameters controlling groundwater occurrence in the Kericho aquifer in Kericho County, Kenya. To achieve this objective, the study utilized a combination of geophysical and pumping test data. Consequently, fifty Vertical Electric Soundings (VES) were carried out to determine the aquifer properties of the study area. Further, seven out of fifty surveyed sites were drilled to depths ranging between 30m and 230m, and test pumping was done for 24 hours. Geophysical results show that the average hydraulic conductivity in the study area varies from 1.96 m day-1 to 6.2 m day-1 . The transmissivity ranged from 35.83 m2 day-1 to 5166.4 m2 day-1 , while the yield ranged between 0.7 and 9.7 M3 /hr. The aquifer hydraulic parameters determined from geophysical and pumping test data were analysed using one-way analysis of variance (ANOVA). The results show no significant difference (p = 0.948151> 0.05) on hydraulic conductivity between geophysical and pumping test methods. Therefore, this study confirmed the reliability of both methodologies for groundwater assessment. Identifying prospective groundwater zones in the research area demonstrates that the combination of these methods is efficient and suited for groundwater exploration. It is suggested that observation wells be added in future studies to allow for the computation of storativity.