Spatio-Temporal Variation of Water Quality in the Yan Oya River Basin, Sri Lanka

River basins are logical units interacting with geological formations and anthropological footprints while providing many rewards to humans and the associated ecosystems. Yan Oya is the primary surface water source in the North Central Province of Sri Lanka. The timely study focused on analyzing the present status of surface water quality in the Yan Oya river basin to evaluate the impacts of anthropological activities. Forty surface water samples were collected in wet and dry seasons in 2019. Principal component analysis (PCA) was employed to evaluate the similarities and dissimilarities of the water quality between three different zones of the Yan Oya river basin. At the same time, GIS was applied to show the spatial distribution of water quality parameters. According to the Sri Lankan Standards for drinking water, pH, DO, NO3-, NO2-, NH4 (+), TP, fluoride, Na+, K+, and trace metal concentrations remained within permissible limits. Electric conductivity (EC), total dissolved solids (TDS), chemical oxygen demand (COD), turbidity, total hardness (TH), fecal coliform, and total coliform were exceeded the allowable threshold levels. PCA analysis revealed that the significance of geomorphological catchment factors and land use features on broad-scale water quality patterns and the study identified that spatial variations in cations ( Na+, K+, Ca2+, Mg2+), TH, EC, and TDS. High FC contamination was the most important factor variable for COD and turbidity in the Yan Oya river. The results yielded spatiotemporal patterns of contamination divided along anthropogenic footprints, serving as a benchmark for future studies, particularly basins that have reservoirs constructed to facilitate better human consumption of water.River basins are logical units interacting with geological formations and anthropological footprints while providing many rewards to humans and the associated ecosystems. Yan Oya is the primary surface water source in the North Central Province of Sri Lanka. The timely study focused on analyzing the present status of surface water quality in the Yan Oya river basin to evaluate the impacts of anthropological activities. Forty surface water samples were collected in wet and dry seasons in 2019. Principal component analysis (PCA) was employed to evaluate the similarities and dissimilarities of the water quality between three different zones of the Yan Oya river basin. At the same time, GIS was applied to show the spatial distribution of water quality parameters. According to the Sri Lankan Standards for drinking water, pH, DO, NO3-, NO2-, NH4 (+), TP, fluoride, Na+, K+, and trace metal concentrations remained within permissible limits. Electric conductivity (EC), total dissolved solids (TDS), chemical oxygen demand (COD), turbidity, total hardness (TH), fecal coliform, and total coliform were exceeded the allowable threshold levels. PCA analysis revealed that the significance of geomorphological catchment factors and land use features on broad-scale water quality patterns and the study identified that spatial variations in cations ( Na+, K+, Ca2+, Mg2+), TH, EC, and TDS. High FC contamination was the most important factor variable for COD and turbidity in the Yan Oya river. The results yielded spatiotemporal patterns of contamination divided along anthropogenic footprints, serving as a benchmark for future studies, particularly basins that have reservoirs constructed to facilitate better human consumption of water.