Aquifer Characteristics and Groundwater Vulnerability in parts of Warri, Delta State, Nigeria

Abstract

Pumping tests are the most important tools for assessing aquifer characteristics. Pumping tests assess the response of groundwater in an aquifer to pumping. Oil exploration and exploitation in Warri and environs have brought about an increase in the population of industries in the area. These have resulted to an upsurge in groundwater abstraction, which if unchecked can endanger the health of the aquifers. The aquifer system in the study area is largely unconfined and comprises of coastal plain-sand also known as the Benin Formation. The aquifer characteristics and groundwater vulnerability of parts of Warri, Niger Delta was investigated via pumping test and hydrochemical analyses respectively. The trasmissivity ranges from 876.1m2/day to 2022.0m2/day while specific capacity varies from 41.84m3/h/m to 96.30m3/h/m. the well yield is of the order of 200cm/h to 208cm/h. These findings indicate that the area has good groundwater potentials and high aquifer recharge. The borehole logs give a good lithostratigraphic profile of the subsurface rocks in the area. Majority of the bacteriological and physic-chemical parameters analyzed were below the guideline values of the Nigerian Industrial Standard (NIS, 2007) and the World Health Organization (WHO, 2006) except coliform count in locations 2 and 3; chromium in locations 3,4,6 and 7 as well as lead in locations 4 and 5 with values slightly above the guideline values. Based on the results, the groundwater vulnerability in the area was categorized into low and high regions.