Prospects and quality indices for groundwater development in Ibadan metropolis, southwestern Nigeria

Abstract

An integrated geophysical and hydrogeochemical studies were conducted in part of Ibadan metropolis, Southwestern Nigeria to investigate the groundwater potential and quality for sustainable development. Interpreted results of vertical electrical sounding data revealed three to four geo-electric layers; top soil (22.1-441.4 Ωm), lateritic horizon (402.1-712.2 Ωm), clayey/sandyclay layer (2.95-66.0 Ωm) and weathered/fractured bedrock (66.3-1056.7 Ωm). Stacked overburden isopach and basement isoresitivity maps revealed few areas with thick overburden and fractured basement, hence of apparently high groundwater prospect. Hydrogeochemical study indicates that groundwater in the study area is generally fresh, soft- moderately hard, slightly acidic and dominated by Na, Ca, Mg, Cl and HCO3 ions. The dominant hydrochemical facies is Na-Cl type with minor mixed Ca-Na-Cl and Ca-Cl types. Many of the analyzed parameters fall within recommended limits and thus, most of the groundwater in the study area are chemically suitable for drinking. A few however, recorded TDS, pH, NO3, Al, Mg and Cl concentrations above permissible levels, suggesting some concern in terms of potability. The groundwater quality for agricultural purposes was assessed using Sodium absorption ratio, permeability index and electrical conductivity values along with USSL and Wilcox diagrams, all indicating that most of the samples are excellent to good for irrigation.

Keywords

• Prospects
• Isoresistivity
• Hydrogeochemistry
• Groundwater quality
• Ibadan