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 severalsample 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 + , Zn 2+ , Mg 2+ , PO 4 3− , Cl − , HCO 3 − , SO 4 2− , and NO 3 − concentrations. Also, ions including Fe 3+ , Zn 2+ , Mg 2+ , Na + , PO 4 3− , and SO 4 2− 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-HCO 3 and Ca-Mg-SO 4-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.

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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.

This review attempted a detailed description of geological and hydrogeological configurations of Cross River and Imo-Akwa Ibo basins. It presented a synthesis of hydrochemistry and a description of the hydrogeological configurations of the two basins. Hydrogeologically, most areas under Cross River and  Imo-Kwa-Ibo are poor in terms of groundwater potentials. Based on the hydrochemistry, the basins hold water of excellent quality.  Groundwater sources fall in soft to moderately hard classes. The entire sources groundwater has a TDS concentration of less than 500 mg/l. Groundwater classification based on electrical conductivity (EC) showed EC levels were less than 500  µS/cm. Most of the examined cations and anions are within WHO reference guidelines for drinking water quality. However, no broad analysis of water quality based on water quality indices. Also, studies modeling pollution or the impact of land use changes on groundwater quality are wanting. Thus, further analysis of the hydrochemistry of groundwater aquifers is recommended.

This review presented a detailed re-assessment of the hydrogeology and hydrochemistry of the Tropical Anambra Basin. It identified and discussed the major geological formations and their groundwater potentials. The geological examination showed that the  Ajali Formation is confined in places forming an artesian condition; the potentials of this aquifer decline in the western basin due to a decrease in thickness. The sandstone associates of the Nsukka Formation are aquiferous and have produced high-pressure artesian boreholes along the Oji River. The Imo Shale is characterized by permeability stability all over much of the intermediate unit. The Bende-Ameki aquifer has a lesser amount of groundwater when equated to other formations; the geologic characteristics do not produce favorable hydrogeological conditions for groundwater occurrence. The stratigraphical and structural framework suggested the presence of an efficient throughflow in the basin. Based on physical and chemical parameters of water quality, the basin holds water of acceptable quality. While there are considerable investigations on the hydrogeology and hydrochemistry, studies are short of analysis of the hydrogeochemical evolution of groundwater, water quality index, heavy metals pollution index as well as total hazard quotient.  Suitability of groundwater based on agricultural water quality indices (e.g. SAR) is also salient. Therefore, future studies should address these owing to increasing dependence on groundwater.