Integrated appraisal analysis of Karnaphuli River water suitability for Chattogram City dwellers in Bangladesh

This is the authors' abstract. We don't add key points for this paper.

The Karnaphuli River, a crucial freshwater source in Bangladesh, is severely threatened due to industrial expansion, unregulated waste discharge, and unplanned urbanization. This study assessed surface water quality in the Karnaphuli River and identified associated health risks by analyzing samples collected from 24 stations during winter for 10 physicochemical parameters and 4 heavy metals. The study employed Water Quality Index (WQI) and the Heavy Metal Pollution Index (HPI), supplemented by spatial analysis (Inverse Distance Weighting), statistical methods (Pearson correlation and PCA), and a survey of local inhabitants through snowball sampling (n=40). The study visualizes pollutant concentration patterns across sampling sites, helping to identify pollution hotspots and high-risk zones along the river. The WQI and HPI findings were concerning. WQI (86.531-475.9) and HPI (80.694-450.45) values indicated that the water was unfit for drinking, with most stations ranging from slightly to strongly polluted. Spatial and statistical analyses showed that pollution levels increased from upstream to downstream, with the left bank exhibiting higher concentrations of Pb (0.0740 mg/L) and Cd (0.0052 mg/L), indicating a direct link to urban and industrial discharges. Most parameters exceeded the standards set by the ECR-2023 and the WHO-2023 guidelines. Moreover, respondents reported widespread skin diseases and confirmed that the river water is unsuitable for drinking, irrigation, or daily use. The results highlight the need for strict enforcement of the ECR-2023, improved wastewater treatment, and ongoing monitoring to protect the environment and public health in the Karnaphuli River.