ANALYSIS OF GROUNDWATER QUALITY PARAMETERS IN NIGER STATE USING ORDINARY KRIGING AND COKRIGING APPROACHES

Abstract

Groundwater is the primary source of water for households in Niger State. However, increasing urbanisation, poor sanitation, and limited monitoring have raised concerns regarding its quality and safety. This study used data on five Ground Water Quality (GWQ) parameters from twenty locations, which comprised five Boreholes (BH) and fifteen Hand-Dug Wells (HDW). Descriptive statistics were used to measure microbial, physical, and chemical parameters in accordance with the World Health Organization (WHO) standard. Geospatial structures in the data were estimated using ordinary kriging and cokriging. The results showed that, in BH, descriptive statistical analysis of Escherichia coli (0 cfu/100mL) concentrations clustered at zero, indicating good water quality. HDW showed a high E. coli count (12 cfu/100mL), indicating contaminated water. BH recorded very low microbial contamination with physical and chemical parameters within WHO limits. While HDW exhibited elevated microbial loads (1–56 cfu) and acidic pH (5.80–6.40), these conditions indicate that the water is not safe for direct consumption, despite acceptable Total Dissolved Solids (260–390 mg/L). Boreholes showed moderate spatial dependence (Z₀ = 0.05–0.15, Z = 0.60–1.85, and a = 1.20–2.80 km), implying that GWQ changes in a similar pattern. The spherical model best fitted the boreholes, while the spherical and exponential models best fitted the wells. Cross-variogram confirmed pH as the preferred auxiliary variable. The coefficient of determination confirmed that Cokriging outperformed ordinary kriging with ( ≥ 0.96). These results imply that boreholes represent the safest groundwater source in Minna. The study recommended routine monitoring, sanitation, and use of prediction maps to prioritise targeted interventions.