Assessing drinking and irrigation water quality in a highly altered subtropical river in India using hydro-chemical indices

River water pollution and the subsequent degradation of water quality for irrigation and drinking are reported worldwide, especially in tropical regions with excess population pressure. The present study intends to investigate irrigation and drinking water quality and assess their suitability in the subtropical Damodar River in India using hydrochemical indices during pre-monsoon (PRM), monsoon (MON), and post-monsoon (POM) periods. The water quality index (WQI) results reveal that the river's water is unsuitable for drinking, as 68.92% (52.95% in PRM, 86.54% in MON, and 66.88% in POM) of samples are found to be unfit for consumption in the temporal dimension. However, in the spatial dimension, the percentage of unsuitable water samples is primarily high near the village of Mujher Mana station, with 97.20% of samples (97.87% in PRM, 97.91% in MON, and 95.83% in POM) deemed unfit for drinking. This suggests the Damodar River water in MON and near the village of Mujher Mana needs treatment before drinking. The study's findings from the irrigation hazards indices and the local farmers' feedback indicate that the river water is suitable for irrigation use. Moreover, SAR, %Na, KR, and PS are high at Mujher Mana village, RSC at Raniganj downstream (Ds), PI at Barakar, and MAR at Durgapur upstream (Us) in terms of spatial extent. The ANOVA test indicates a significant variation in river water quality across different spatio-temporal dimensions in the study area. Water pollution is mainly attributed to the discharge of untreated industrial and urban effluents directly into rivers, without undergoing water treatment. Therefore, it is imperative to address the issue promptly to reinstate the river water quality.