Impact of COVID-19 lockdown on real-time DO-BOD variation of river Ganga

A comparative assessment of dissolved oxygen (DO) and biochemical oxygen demand (BOD) of river Ganga during prelockdown and lockdown periods was made through analysis of data generated from real-time water quality motoring systems. The concentration data for DO and BOD are examined for (i) prelockdown period (March 15-21, 2020) and (ii) lockdown period (March 22-April 15, 2020). The analysis results show 3%-20% decrease in DO concentration. The slight decrease in DO observed at all locations during the first week after lockdown which may be due to the increased levels of suspended solids and turbidity in the river water because of heavy rains. DO during fourth week of lockdown has shown a decreased value as compared to the prelockdown period at most of the locations. However, in West Bengal the DO has increased in lockdown. BOD value ranged between 1.13 mg/L and 5.56 mg/L during lockdown period, more or less similar to prelockdown range of 1.37-5.58 mg/L. This chapter further discusses the cause of water quality changes during the period of lockdown as compare to prelockdown period. © 2021 Elsevier Inc.

Water quality assessment of the Ganges River during COVID-19 lockdown.

Ganges River water quality was assessed to record the changes due to the nation-wide pandemic lockdown. Satellite-based (Sentinel-2) water quality analysis before and during lockdown was performed for seven selected locations spread across the entire stretch of the Ganges (Rishikesh-Dimond Harbour). Results revealed that due to the lockdown, the water quality of the Ganges improved with reference to specific water quality parameters, but the improvements were region specific. Along the entire stretch of Ganges, only the Haridwar site showed improvement to an extent of being potable as per the threshold set by the Central Pollution Control Board, New Delhi, India. A 55% decline in turbidity at that site during the lockdown was attributed to the abrupt halt in pilgrimage activities. Absorption by chromophoric dissolved organic matter which is an indicator of organic pollution declined all along the Ganges stretch with a maximum decline at the downstream location of Diamond Harbour. Restricted discharge of industrial effluent, urban pollution, sewage from hotels, lodges, and spiritual dwellings along the Ganges are some of the reasons behind such declines. No significant change in the geographic trend of chlorophyll-a was observed. The findings of this study highlight the importance of regular monitoring of the changes in the Ganges water quality using Sentinel-2 data to further isolate the anthropogenic impact, as India continues the phase-wise opening amidst the pandemic.