Evaluation of the Groundwater Potential in Ngor-Okpala, Imo State, Nigeria

Abstract

Rapid urbanization being experienced in Ngor-Okpala has resulted in increased groundwater abstraction. As a result, accurate estimation and proper evaluation of the groundwater potential in the area becomes necessary for accurate utilization and management of the resources. The aquifer characteristics and groundwater occurrence in the area was evaluated using geophysical survey, borehole logs, sieve analysis and pumping test results. The area lies within the coastal plain sand aquifers of southeastern Nigeria which is composed of loosely consolidated sands, sandstones and gravels with minor intercalations of silt and clays. This study is an initial step towards providing information needed for effective management of the groundwater system in the area. The geophysical survey and borehole logs show that the area is sand dominated. The borehole logs and sieve analysis results indicate: coarse grained sand > medium grained sand > fine grained sand > gravel > (silt & clay). Pumping test gives transmissivity values ranging from 214m2/d to 396m2/d with a mean value of 306m2/d while the storativity varies from 4.0 x 10-2 to 3.4 x 10-1 with an average value of 2.5 x 10-1. The borehole yield is of the order of 2459m2/d to 5622m3/d and mean value of 3207m2/d while the hydraulic conductivity varies from 4.33m/d to 15.16m/d with an average value of 10.61m/d. These findings indicate that the area high groundwater potentials.