Groundwater under Basement Complex areas of southern Kebbi has been characterized in order to determine its suitability for drinking and irrigation use. Water samples were drawn from shallow groundwater (hand-dug shallow wells < 5 m) and deep groundwater (boreholes > 40 m). Physical parameters (i.e., temperature, TDS, pH, and EC), were determined in situ, using handheld meters. Discrete water samples were obtained for determination of chemical parameters. Results from several-sample ANOVA (Kruskal–Wallis test) suggested that heterogeneity in water table appeared to exert significant influence on groundwater chemistry which is characterized by a significant difference in pH, EC TH, Na⁺, Zn²⁺, Mg²⁺, PO₄³⁻, Cl⁻, HCO₃⁻, SO₄²⁻, and NO₃⁻ concentrations. Also, ions including Fe³⁺, Zn²⁺, Mg²⁺, Na⁺, PO₄³⁻, and SO₄²⁻ are above World Health Organization (2011) and National Standard for Drinking Water Quality (2007) reference guidelines. Most of the groundwater sources are moderately hard. Groundwater classification based on chloride, EC, and TDS revealed water of excellent quality for all types of uses. However, groundwater classification based on nitrate pollution revealed water of poor quality. Rock mineral is the major mechanism controlling water chemistry, as revealed by the Gibbs model. Most of the water sources have positive Scholler index, indicative of overall base exchange reactions in the underlying aquifers. Such condition was well explained by Piper trilinear diagram, which revealed two types of faces: Ca–Mg–HCO₃ and Ca–Mg–SO₄–Cl. The HCA categorized wells into three groups according to their hydrogeochemical physiognomies. Despite the significant difference in ions concentration and chemical indices, groundwater composition is more influenced by rock weathering than anthropogenic inputs. Groundwater evaluation for irrigation use indicates a significant difference in SAR level which is related to poor permeability index in shallow groundwater. Higher values of Kelly’s index and magnesium adsorption ratio threatened groundwater suitability for irrigation use in the study area.

The hydrogeochemistry of aquifers in the western Sokoto basin was assessed. The objective of this study is to identify the impact of geological variability on groundwater hydrochemistry and the mechanisms controlling the hydrochemistry of aquifers. Univariate statistics (several samples ANOVA), Pearson’s (r), and multivariate statistics-hierarchical cluster analysis (HCA) and Factor analysis (FA) were used to interpret the hydrochemistry of aquifers. Subsequently, geochemical modeling was applied to assess the saturation index (SI) of rock minerals. Forty groundwater samples were collected from Gwandu (n = 20) and Illo (n = 20) formations. ANOVA results indicated that geological variability exerted a considerable impact on groundwater in Gwandu and Illo aquifers. It is characterized by a substantial amount of Ca²⁺, Mg²⁺, SO₄²⁻, HCO₃⁻, Na⁺, and K⁺. The hydrogeochemical facies indicated mixing conditions. FA and correlations analysis further revealed that groundwater received the noticeable influence of silicate weathering and dissolution of carbonates. There were significant differences in SI values for chrysotile, goethite, gypsum, H₂(g), H₂O(g), H₂S(g), illite, and sepiolite minerals between the two geologic environments. Positive SI values for gibbsite were noticed in eleven sampling locations, indicative of potential recharge zones. Likewise, all the sampling locations have positive values for K-feldspar and are supersaturated with mica, suggesting both discharge and transition zones. The HCA classified aquifers into three clusters based on their hydrogeochemical characteristics. Geochemical modeling, univariate, and multivariate analyses are user-friendly tools for hydrochemical analysis.

Understanding the hydrochemical and hydrogeological physiognomies of subsurface water in a semi-arid region is important for the effective management of water resources. This paper presents a thorough review of the hydrogeology and hydrochemistry of the Hadejia-Yobe basin. The hydrochemical and hydrogeological configurations as reviewed indicated that the Chad Formation is the prolific aquifer in the basin. Boreholes piercing the Gundumi formation have a depth ranging from 20-85 meters. The hydrochemical composition of groundwater revealed water of excellent quality, as all the studied parameters were found to have concentrations within WHO and Nigeria’s standard for drinking water quality. However, further studies are required for further evaluation of water quality index, heavy metal pollution index, and irrigation water quality. Also, geochemical, and stable isotope analysis is required for understanding the provenance of salinity and hydrogeochemical controls on groundwater in the basin.