Assessing the water quality and human health risks in surface and hyporheic zone: study from Damodar River, Eastern...

The Damodar River, a vital tropical fluvial system in eastern India, faces escalating contamination from anthropogenic activities, yet integrated assessments of surface and hyporheic water quality remain limited. This study addresses this gap by evaluating pollution dynamics, ecological risks, and human health hazards across both zones during pre- and post-monsoon seasons. Utilizing a GIS-based framework, 120 water samples (60 surface, 60 hyporheic) were analyzed for 20 parameters, including heavy metals, nutrients, and physicochemical properties. Indices (MWQI, HPI, PERI, TSI, HHHI) and multivariate analyses (PCA, clustering) were employed to quantify contamination, map spatial-temporal patterns, and assess risks. Results revealed severe heavy metal pollution, with hyporheic zones exhibiting higher contamination than surface water: 100% of hyporheic samples were "highly polluted" (MWQI), and 48.14% exceeded drinking safety thresholds (HPI > 100). Ecological risk indices indicated moderate contamination (PERI: 150-300), while trophic status reflected low eutrophic conditions (TSI: 50-60). Non-carcinogenic health risks were significant for children (HHHI > 1), particularly post-monsoon, but negligible for adults. Seasonal dilution effects were minimal, and clustering highlighted pollutant-nutrient associations pre-monsoon, shifting to biological-organic linkages post-monsoon. The hyporheic zone emerged as a critical contamination reservoir, influenced by industrial discharges and hydrological shifts. This study underscores the necessity of targeted remediation in hyporheic zones, stricter pollution regulation, and child-centric public health interventions. By integrating geospatial and multivariate approaches, it advances holistic water management strategies for dam-regulated tropical basins, aligning with Sustainable Development Goals for clean water and ecosystem resilience.