Groundwater Vulnerability Assessment of Parts of Southern Bida Basin, Southwestern Nigeria Using DRASTIC Method

Abstract

The DRASTIC Index approach has been employed to assess the susceptibility of groundwater in parts of the Southern Bida Basin, Southwestern Nigeria to pollution. This research was required due to uncontrolled disposal of residential and agricultural waste by residents, which has resulted in groundwater contamination. In addition, the assessment of groundwater vulnerability to contamination has become an important element for land-use planning and groundwater resource management. The DRASTIC index employs seven hydrological parameters, namely depth to groundwater table, net recharge, aquifer media, soil media, topography, impact of vadose zone, and hydraulic conductivity to generate vulnerability maps. The groundwater vulnerability map was prepared using index and overlay analysis with the aid of Arc GIS 10. The calculated DRASTIC vulnerability scores in the basin range from 71 to 180 which divided the study area into low-moderate and moderate-high risk zones. The value range for the low-moderate zone is 71–160, while the moderate-high zone has a value range of 160–180. Communities located in the Patti and Agbaja Formations have showed a vulnerability index that varies from low to moderate. On the other hand, settlements in the Lokoja Formation have a vulnerability rating that varies from moderate to high; these communities are particularly prone to contamination. This sensitivity can be attributed to shallower groundwater depths, sandy aquifer materials, slope of the area, and gravelly vadose zones with the Formation. Hence, Policies should be put in place to make it easier to close possible pollution sources in moderate to high vulnerability areas, such as open dump sites, agricultural areas, effluent discharge from industries, and sewage disposal units..

Publication Info:

Author: Olaleye, I.M. , Ige, O.O. and Oyeleke, T.A.

Volume: 60

Issue: September

Published By: Olaleye, I.M. , Ige, O.O. and Oyeleke, T.A., 2024-09-01