Long term trend analysis and suitability of water quality of River Ganga at Himalayan hills of Uttarakhand, India

Abstract

Abstract River Ganga flows in the northern part of India and is treated as sacred water resource. The river receive huge amount of partially treated and untreated waste from industrial, agricultural, and religious activities being practiced across the flow, causing deterioration of water quality (WQ) of the river. The present study aims to assess the pollution status and trend of WQ in the river and its primary tributaries (river Bhagirathi and Alaknanda) based on 49 years (1971–2020) data from various locations using water quality index and graphical trend analysis based on a Cartesian coordinate system with 1:1 (45°) line as a benchmark. The results reveal that the WQ in the rivers was good as the estimated values of all WQ parameters were within their permissible limits for drinkable water. The river water was suitable for agriculture activity as sodium-absorption-ratio (SAR) was less than 10 at all sampling-locations. The river WQ was slightly polluted during year 2015–18 as the comprehensive pollution index was in the range of 0.40–1.00. The WQ trend analysis revealed that the parameters pH, Cl − , F − , K + , Na + , SO 4 − 2 , BOD 3 27 , and SAR were altered over time at all sampling-locations. Among all parameters, only SO 4 − 2 concentration gained an incremental trend at all sampling-locations. The decreasing trend of pH and dissolved oxygen concentration was noted at the downstream locations, which reveals that the river WQ might decline if the same scenario remains unchanged in future. The result has implications for the water resource planners, managers, policymakers, and environmentalists responsible for the preservation and restoration of WQ of Ganga and may serve as a strategic model for other major rivers in the region.