Hydrogeochemical Characterization and Quality Assessment of Groundwater in the Nkwanta Enclave, Oti Region, Ghana

Groundwater is the main source of drinking and irrigation water in the Nkwanta enclave of Ghana, making its quality essential for public health and agriculture. This study assesses the hydrogeochemical characteristics of groundwater in the region and evaluates its suitability for domestic and agricultural use. The area’s geological setting plays a key role in influencing groundwater chemistry, particularly through water-rock interactions and ion-exchange processes. To understand the sources and behaviour of dissolved ions, the study applied graphical methods, bivariate plots, and multivariate statistical tools, including principal component analysis (PCA) and hierarchical cluster analysis (HCA). The results show that most groundwater samples fall within acceptable limits for drinking water, based on the World Health Organization standards. The dominant water types identified were Na–Mg–HCO₃ and Na–HCO₃, with several mixed facies also present. Irrigation water quality assessment revealed sodium adsorption ratio (SAR) ranging from 0.01 to 6.06, with a mean of 2.15, indicating low sodium hazard for irrigation. The magnesium ratio ranged from 31% to 100%, averaging 82%, while sodium percentage varied between 2.00% and 96.00%, with a mean of 58%. These values suggest that the water is generally suitable for irrigation, though the high magnesium content in many samples could negatively affect soil structure by reducing infiltration and hydraulic conductivity. To address this, the use of calcium-rich amendments such as gypsum is recommended. This study not only characterizes the chemical composition of groundwater but also identifies the natural and anthropogenic processes influencing its quality. By mapping areas with elevated concentrations of key ions, it provides a basis for targeted monitoring and management, offering practical guidance for local communities, environmental managers, and policymakers.