Hydrogeochemical Evaluation of Groundwater Quality in the Yola Arm, Upper Benue Trough, Northeastern Nigeria

Abstract

Groundwater constitutes the principal source of potable water in Pariya and its environs within the Yola Arm of the Upper Benue Trough, Northeastern Nigeria. However, increasing population pressure, agricultural practices, and inadequate sanitation pose growing threats to its quality. This study evaluates the hydrogeochemical characteristics and suitability of groundwater for drinking using integrated hydrochemical and multivariate statistical approaches. Twenty three groundwater samples were collected from boreholes and hand-dug wells and analyzed for major physicochemical and microbiological parameters following standard procedures. Hydrogeochemical interpretation employed the Water Quality Index (WQI), Piper trilinear diagram, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA) to identify water types and the dominant processes controlling groundwater chemistry. The groundwater is slightly acidic to neutral, with pH values ranging from 5.88 to 7.10. Electrical conductivity (210–312 µS/cm) and total dissolved solids (136–243 mg/L) indicate low to moderate mineralization. Major ions generally fall within World Health Organization (WHO) permissible limits. Turbidity ranges from 0.03 to 13.14 NTU, with only one sample exceeding the recommended threshold. In contrast, coliform bacteria exceed acceptable limits in approximately 70% of the samples, revealing widespread microbial contamination linked to poor sanitation and surface infiltration. WQI values range from 32.41 to 202.61, classifying 86.9% of the samples as suitable for drinking (Grade B), while 4.3% are poor (Grade C), 4.3% abysmal (Grade D), and 4.3% unsuitable (Grade E). Piper plots reveal dominant Ca–Mg–HCO₃ and Ca–Mg–SO₄–Cl facies, indicating that groundwater chemistry is primarily controlled by carbonate and silicate weathering, mineral dissolution, and reverse ion exchange. PCA and HCA identify natural mineralisation, rock–water interactions, Na-alkalinity, and localised fertiliser inputs as the principal factors influencing groundwater composition. The results demonstrate that groundwater in the study area is generally suitable for irrigation and domestic use; however, microbial contamination necessitates disinfection before consumption. Strengthening sanitation infrastructure, regulating fertiliser application, and implementing periodic groundwater monitoring are essential to safeguard public health and ensure sustainable groundwater management in the Yola Arm.