Reduction in turbidity of Indian lakes through satellite imagery during COVID-19 induced lockdown

The lakes of India are getting significantly polluted due to the rapid growth of industries, plastics, and anthropogenic waste. Due to the non-functioning of the industries and human activities during the COVID-19 pandemic lockdown, industrial and other waste going to the lakes was significantly reduced. Moreover, with the reduction of human activities and tourism in the cities and lakes, anthropogenic pollution in the lakes was also reduced. Turbidity is the key indicator of water pollution in the lakes. It has a direct relationship with surface water reflectance and can be estimated through satellite imagery. In this paper, the relative comparison of turbidity values of five Indian lakes in the Rajasthan state was done through Satellite imagery of Sentinel-2 during the pre-lockdown and lockdown period. The relative turbidity is also calculated through reflectance values of Satellite images and then the empirical method is applied to the reflectance values of the red band of Sentinel-2 & Landsat-8 data to estimate the turbidity. Relative comparisons of turbidity values estimated through satellite imagery during the pre-lockdown and lockdown period showed that the turbidity of lakes was reduced in Kaylana Lake (49.6%), Fatehsagar Lake (55.4%), Pichola Lake (54.3%), Rajsamand Lake (58.3%), and Man Sagar Lake (44.8%) during the lockdown period. Spectral curve analysis also showed that there was a decrease in the surface water reflectance in all five lakes and this indicates the reduction in the turbidity of the water during the lockdown period.