This study was conducted to investigate the influence of hydrogeological processes on the water systems of the Uburu-Okposi area situated in the Lower Benue Trough. The aim was to analyze how the interaction between aquifer materials and water impacts its chemical composition. Forty (40) water samples, collected randomly from both groundwater and surface sources, underwent thorough analysis to determine their physicochemical properties. In situ measurements revealed pH ranging from 5.29 to 8.98, EC ranging from 206 to 6970 microsiemens per centimeter (µS/cm), and TDS ranging from 112 to 4690 milligrams per liter (mg/L). Laboratory analysis highlighted sodium ions (Na+) as the most abundant cation, with concentrations ranging from 4.4 to 49,000 mg/L, and chloride ions (Cl-) as the predominant anion, with concentrations ranging from 14.4 to 63,000 mg/L, indicating signs of salinization. Factors affecting water chemistry were determined using Saturation Index (SI), ionic ratio, and bivariate plots. Analysis showed that 65% of the samples exhibited a positive Chloro Alkali Index (CAI) ratio, suggesting that direct base-exchange reactions are the primary influencers of water chemistry. Cation exchange, evidenced by large absolute values in CAI 1&2, significantly influenced groundwater chemistry. Saturation Index (SI) estimations revealed supersaturation of dolomite, calcite, aragonite, and magnesite, impacting water chemistry. Bivariate plots highlighted the significant influence of ion exchange, particularly carbonate and silicate weathering, on water chemistry. Gibbs plot analysis indicated that 92.5% of samples fell within the rock-water interaction field, while 7.5% were within the evaporation-precipitation field. Principal Component Analysis (PCA) identified six component factors, with the first three collectively explaining over 50% of the total variation. These factors primarily relate to hydrochemical processes, including water-rock interactions, carbonate dissolution, and ion exchanges. Geogenic factors emerged as the primary influencers on water chemistry in the study area, as revealed by the results.

Keywords: Ion exchange, Saturation Index, Principal Component Analyses, Chloro Alkali Index, Bivariate