Impact of extreme climatic events on the total suspended matter concentrations in coastal waters using OceanSat-2 observations

Abstract

Variations in rainfall and associated erosion levels on the land are the main factor that determines seasonal shifts in coastal ocean color variables. Extreme climate and weather events such as floods and rainfall induced landslides can cause significant impact on water quality property in coastal areas. Studies showing quantitative variability of total suspended matter (TSM) in coastal waters in response to extreme rainfall events are rarely attempted due to the lack of observational and cloud free satellite data products. Here, we investigate the effects of extreme floods that occurred during 14–19 August 2018 in the Western Ghats, and their impacts on TSM concentrations in coastal waters by analyzing OceanSat-2 images. Our results show that the TSM level during the flood stages was more than twice that of normal periods. The excess amount of sediment load from terrigenous sources transported through the rivers has impacted in high TSM concentrations (>23 mg/l) in the coastal waters as compared to normal conditions (<10 mg/l). Furthermore, we noticed that the strong wind mixing and its directionality had a significant impact on resuspension of TSM distributions and their dispersal pathways in Kerala coast.