Spatio-Temporal Analysis on the Optical Properties of Vembanad Lake, Kerala, India – A Remote Sensing Approach

Abstract

Abstract Water quality is one of the most essential parts of environmental monitoring; even a little variation in its characteristics may have a large influence on the ecosystem. The water quality parameters such as diffuse attenuation (Kd(490)), turbidity, Suspended Particulate Matter (SPM) and Chlorophyll-a (Chl-a) are considered in this study to evaluate the water quality of Vembanad Lake, Kerala, India. The lake is considered of ecological importance by the Ramsar Convention and has faced serious concerns over the recent years. This study aims to examine the change in the water quality using Sentinel-2 satellite data in the ACOLITE software from 2016 to 2021. The analysis showed 2.5% decrease in the values of Kd whereas SPM and turbidity show a decrease of about 4.3% from the year 2016 to 2021. The flood and the COVID lockdown had an impact on the improvement in the quality of water during this time. There is an anticipation of the increase in Chl-a content during the period but there is no substantial change in the Chl-a till the year 2020 whereas 2021 showed a 12% decrease in the Chl-a values. This may be due to the reduction in the Hydrological Residence Time (HRT) in the lake.