In the heart of Nagpur, Maharashtra, the Nag River flows as a vital artery, yet it bears the brunt of rapid urbanization and industrialization. A recent study published in the journal *Applied Water Science* (translated as “Applied Water Science”), led by Damini Bramhankar of the PG & Research Department of Chemistry at Hislop College, RTM Nagpur University, offers a groundbreaking approach to understanding and addressing the river’s critical pollution levels. The research integrates Water Quality Index (WQI) with Principal Component Analysis (PCA) and Cluster Analysis (CA) to provide a detailed, spatially resolved assessment of pollution sources along the Nag River’s 17-kilometer urban corridor.
The Nag River, serving as the primary drainage system for Nagpur, is severely polluted due to uncontrolled industrial discharges and municipal sewage. Conventional physicochemical assessments have been inadequate in providing the quantitative, spatially resolved source apportionment necessary for targeted remediation. Bramhankar’s study aims to fill this gap by offering a structured, data-driven assessment of pollution sources.
“Our goal was to holistically assess the surface water quality and quantitatively identify, map, and attribute pollution sources along this critical stretch,” Bramhankar explains. The study collected nine surface water samples during the pre-monsoon season, covering segments influenced by diverse residential, commercial, and industrial land use. Twenty physicochemical and biological parameters were analyzed, with the reliability of the hydrochemical data confirmed using the Ionic Balance Error (IBE) validation.
The results were stark. WQI values ranged from 47.05 (Good) at the upstream baseline to a maximum of 6440.38 (Unfit for all practical uses) at Yashwant Stadium, confirming chronic heavy pollution. This degradation is primarily attributed to untreated municipal sewage, as indicated by extreme Biochemical Oxygen Demand (BOD) levels up to 216.28 mg/l and non-compliant specialized industrial discharges.
PCA identified three primary Varifactors (VFs) explaining 87.935% of the total variance. Varifactor 1 (44.088%) confirmed the overwhelming dominance of untreated municipal sewage (organic load, total dissolved solids, and microbiological parameters). Varifactor 2 (16.666%) was strongly associated with specialized heavy metals (Nickel and Cadmium), indicating a distinct point source industrial effluent. CA successfully categorized sampling sites into four spatial pollution clusters (C1-C4), enabling the identification of high-priority pollution hotspots that correlate directly with land use.
This integrated approach provides critical insights to support evidence-based river restoration and sustainable watershed management planning. The study’s findings are particularly relevant for the energy sector, where water quality is paramount for cooling processes in power plants and other industrial applications. Understanding and mitigating pollution sources can ensure a more reliable and sustainable water supply, reducing operational risks and costs.
Bramhankar’s research not only sheds light on the current state of the Nag River but also offers a model for similar urban water bodies worldwide. By combining WQI, PCA, and CA with land use assessment, the study provides a comprehensive toolkit for targeted remediation efforts. This approach could be instrumental in shaping future developments in water quality management, ensuring that urbanization and industrialization do not come at the cost of environmental degradation.
As cities continue to grow and industries expand, the need for such detailed and actionable insights becomes ever more critical. Bramhankar’s work serves as a beacon, guiding policymakers, urban planners, and industry leaders towards a more sustainable and resilient future.