Impact of lockdowns and possible quantification of pollution sources on the water quality of the Yamuna River

ABSTRACT The COVID-19 lockdown halted industrial and transportation networks, resulting in a change in the level of pollution. In this study, the analysis of pre- and post-lockdown water quality of the Yamuna River is done, and primary causes are identified, by considering five in situ parameters and four Landsat-8-derived parameters. During the 2020 lockdown, pollution-indicating in situ parameters decreased, with chemical oxygen demand decreasing the most, possibly due to reduced industrial impact. All satellite-derived indices improved during lockdown and post-lockdown periods of 2020. Even in segments with uniform flow, floating algal index and normalized difference vegetation index exhibited lower levels. In contrast, the examination of the 2021 lockdown revealed no noteworthy insights. Mapping the observations with the drainage network and location of common effluent treatment plants revealed that industrial effluents were the dominant cause of water quality fluctuations. This demonstrates the impact of industrial effluents on the degrading water quality of Yamuna.