Evaluation of Groundwater Quality and Potability Based on Land Use Variations: A Case Study from Mahiyanganaya, Sri Lanka

This study evaluates groundwater quality and its suitability for drinking, highlighting the impact of land use patterns on water composition. Groundwater samples from 18 wells were analyzed for essential physicochemical parameters, including pH, dissolved oxygen (DO), electrical conductivity (EC), Total dissolved solids (TDS), Alkalinity, Total hardness (TH), Calcium, Magnesium, Sodium, Potassium, Sulfate, and Chloride. The results were compared to World Health Organization (WHO) guidelines for potable water. Spatial distribution analysis, utilizing ArcGIS Pro and the inverse distance weighting (IDW) method, revealed notable deterioration in groundwater quality in urban and paddy field areas due to anthropogenic influences, while forested regions exhibited superior water quality. The findings revealed that 33% of samples from paddy fields, 58% from urban and residential areas, and 83% from forested regions complied with WHO-recommended limits. Hydro-chemical facies were predominantly Ca–Mg–HCO₃, indicating significant geological and anthropogenic influences on water quality. The study concludes that while groundwater remains largely suitable for drinking, continuous monitoring and targeted management strategies are crucial in urban and paddy regions where elevated hardness levels pose contamination risks, thus ensuring the sustainable protection of this vital resource for drinking purposes.