Covid-19 pandemic: Impact and assessment of water quality in the lower Ganga riverine system, India

Abstract

The COVID-19 pandemic and its associated lockdown imposed all over India from 25th March 2020 to 14th April 2020 have made a significant impact on all sectors of life and livelihood including inland fisheries. However, the intensity and extent of the impact on inland open water resources especially rivers and associated water bodies is still unclear. In this study, an immediate and clear effect was observed in the quality of water flowing through the river Ganga. In consideration of pandemic conditions and difficulty in gathering field data, this study attempts to determine the river water quality in terms of turbidity, based on remote sensing imagery data. These changes have been recorded and analysed using Sentinel-2 multispectral remote sensing data for the lower stretches of river Ganga, for selected five stretches covering an approximate mid-channel length of 537 km. The highest sensitivity for turbidity was found in the red and NIR bands among all the bands which were used to estimate turbidity. Temporal variations were also studied through Normalized Difference Turbidity Index at each of these small stretches. A very steep decline in turbidity in the river water has been observed in each of the stretches. The study improved the understanding that the remote sensing approach is capable of assessing the water quality of river turbidity to a greater extent when there are strong hurdles to collecting research data from field studies.