Impact Assessment of Geogenic and Anthropogenic Pressures on Water Quality in Ramganga River Basin in Himalayan Region

ABSTRACT

River Ramganga, a tributary of river Ganga, plays a vital role in supporting industrial, domestic, and agriculture sectors in Uttarakhand and Uttar Pradesh, India. However, the water quality is degraded due to anthropogenic pressures and geohazard‐induced activities, particularly in landslide‐prone Himalayan terrain. Study aimed to assess the freshwater quality of Ramganga River and its tributaries (Dhela and Dhandi) with samples collected from selected seven sites over a year and analyzed using water quality index (WQI), heavy metal pollution index (HPI), heavy metal evaluation index (HEI), and principal component analysis (PCA). WQI ranged from 62.65 (poor) at the upstream Dhela site to 204.91 (unsuitable for drinking) at the Dhandi–Dhela confluence, whereas downstream sites were also classified as unsuitable (WQI > 140). HPI values exceed the critical level (>30) at all sites, whereas HEI values (2.93–9.83) placed the river in the low‐risk class with cumulative metal concentrations. Increased BOD (up to 75.78 mg/L), COD (up to 223.10 mg/L), hardness (>200 mg/L), and Fe and Pb frequently exceeding Bureau of Indian Standard (BIS) limits highlight severe deterioration of water quality and potential health risks. HPI and HEI revealed significant metal contamination, whereas WQI suggested the unsuitability for consumption. PCA highlighted total dissolved solids (TDS) as the highest loading factor, whereas phosphate was the lowest, reflecting the interactions between geohazard‐induced sediment mobilization and water quality. Similarly, PCA of heavy metals showed Zn and Fe as the principal contributors linked to geomorphic instability enhanced by erosion and landslide. These findings highlighted the urgency of strategic water stress management to enhance resilience, mitigate contamination, and ensure sustainable usage of river Ramganga system.