Associations of anthropogenic activity and tributaries with the physicochemical, nutrient and microbial composition of the Ganga (Ganges) River, India

Clayton, Gillian E; Richards, Laura A; Fox, Bethany G; Thorn, Robin M S; Bowes, Michael J; Read, Daniel S; Tipper, Holly J; Khamis, Kieran; Dutta, Tapan K; Kumar, Arun; Hazra, Moushumi; Howard, Ben; Schneidewind, Uwe; Armstrong, Linda K; Nicholls, David J E; Davies, Helen; Hannah, David; Nel, Holly A; Ghosh, Ashok; Joshi, Himanshu; Gooddy, Daren C; Polya, David A; Krause, Stefan; Reynolds, Darren M

Abstract

The Ganga River (known internationally as the Ganges) is one of the world's most prominent rivers, running from the Himalayas to the Bay of Bengal and supporting the livelihoods of > 40 % of India's 1.4 billion population. The Ganga River is regionally and globally important, supporting agriculture and industry, yet faces potentially detrimental water quality challenges arising from runoff and discharge from increasing urbanization, industry and agriculture. A ∼ 2700 km longitudinal survey of the nutrient and microbial water quality, including phytoplankton composition, of the Ganga River was undertaken in November 2019. The aim was to investigate if and how anthropogenic activities (e.g. urbanisation, industry, and agriculture) and tributary convergence (potentially reflecting both human activity and flow influences) affect and shift physicochemical, nutrient, and microbial water quality parameters along the river continuum. Segmented regression identified four zones of distinct nutrient/microbial characteristics along the Ganga River, with breakpoints located near Kanpur, Varanasi and downstream of the Farakka Barage, at distances of ∼ 1020, ∼ 1500 and ∼ 2350 km downstream from the Himalayan Ganga source. Population density, land use and urban cover were associated with selected water quality parameters in parts of the catchment, with elevated nutrient, microbial and chemical concentrations likely associated with agriculture, industry, and sewage inputs. Some urban areas (e.g. Kanpur and Varanasi), converging tributaries (e.g. Yamuna and Varuna) and barrages (e.g. Farakka) were associated with changes in nutrient availability, microbial activity/abundance and modelled discharge, likely driving apparent water quality changes in the relevant locations. Downstream shifts in nutrient and microbial water quality parameters were observed throughout the ∼ 2700 km Ganga River continuum. This information can help prioritize locations for targeted monitoring and/or remediation interventions and has illustrated an approach to quantify impacts of anthropogenic inputs on major river systems, such as the Ganga River. [Abstract copyright: Copyright © 2025 The Author(s). Published by Elsevier Ltd.. All rights reserved.]

• Journal Article Type: Article
• Acceptance Date: Feb 22, 2025
• Online Publication Date: Feb 25, 2025
• Publication Date: Jun 15, 2025
• Deposit Date: May 12, 2025
• Publicly Available Date: May 14, 2025
• Journal: Water research
• Print ISSN: 0043-1354
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 278
• Article Number: 123374
• DOI: https://doi.org/10.1016/j.watres.2025.123374
• Keywords: Microbial activity, Flow cytometry, Ganga River basin, Breakpoint analysis, Water quality, Nutrient availability
• Public URL: https://uwe-repository.worktribe.com/output/13970095