Hydrochemical Characterization of Ground and Surface Water for Irrigation Application in Nigeria: A Review of Progress

Irrigation is a very important practice that helps to ensure all-year-round food security, which is one of the Sustainable Development Goals targets. However, irrigation development in Nigeria has not been fully harnessed despite the huge investment allocated to it. Nigeria has a good quality water-stressed environment where surface and groundwater serve as the main sources of water for several purposes. This has put the water under serious anthropogenic pressure from unconscious and uninformed citizens. This review was aimed at assessing the baseline hydrochemical characteristics of surface and groundwater in different zones of Nigeria with respect to the hydrchmical facies, water type and dominant cations and anions. Understanding the flow patterns, origins, and chemical histories of ground-water masses can be accomplished with the help of hydrochemical facies interpretations. In a bid to achieve this aim, over fifty two articles that reported hydrochemical studies on surface and groundwater in Nigeria were examined. The articles were divided into groundwater articles, surface water articles, and articles that considered both together. The common water types observed in the different regions of Nigeria were: Northwestern Nigeria (Na–HCO₃⁻–Cl, Ca–Mg–HCO₃⁻–Cl, Na–Ca–Cl, Ca–Mg–HCO₃⁻ and Ca–Mg–SO₄²⁻–Cl). Southern part (Ca–Mg, HCO₃⁻–CO₃²⁻, Na–HCO₃, NaHCO₃⁻–Cl, Ca²⁺–Mg²⁺–Cl⁻–SO₄²⁻, Na–Cl, Ca–Na–HCO₃⁻–Cl and Na⁺–K⁺–Cl⁻–SO₄²⁻) with Ca–Mg–CO₃²⁻–HCO₃⁻ and Na⁺–K⁺–Cl⁻–SO₄²⁻ water facies as the dominant hydrochemical facies. The northeastern part had Ca–HCO₃⁻, Na–HCO₃⁻, Ca–Mg–HCO₃⁻ and Ca–Mg–SO₄²⁻–Cl facies predominantly. Southwest recorded the largest number of hydrochemical facies with Na–(K)–HCO₃⁻, (Cl + SO₄²⁻ + HCO₃⁻) + (Cl + SO₄²⁻), Na⁺–SO₄²⁻ type (according to Base Exchange Indices), while meteoric genesis indices (showing the various water types and percolation depth) indicated deep meteoric water percolation type. Besides, the primary hydrochemical facies were found to be Na(K)–HCO₃⁻ (minor) and Ca(Mg)–HCO₃⁻ (dominant) water types, which could be associated with mineral dissolution in the different rock units, according to the overall hydrochemical profiles. Two major water facies (the Mixed Ca–HCO₃⁻ and Ca–Mg–Cl) were revealed by the Piper diagram, while samples in the region were primarily influenced by precipitation as a minor influencer and rock weathering/mineral deposition as a major influencer from the Gibbs’ plot perspective. The hydrochemical facies of the south-south (SS) and north-central (NC) regions were not available due to insufficient articles from the regions. Despite the large number of articles reviewed, there was no comprehensive water quality analysis from each article. We therefore hope that this review will stimulate further research in SS and NC. By implication, this review has shown that in respect of water-types, ground and surface water in Nigeria is of good quality for irrigation application, but we must put on notice that water quality changes with time and location.