Total Suspended Matter Distribution in the Hooghly River Estuary and the Sundarbans: A Remote Sensing Approach

Abstract

Monitoring of total suspended matter (TSM) concentration in the coastal waters is vital for water quality monitoring and coastal management. In this study, TSM over the highly dynamic Hooghly estuary region is derived using MODIS surface reflectances at 645 nm and in-situ TSM observations. MODIS TSM products show a correlation of 0.95, root mean square error of 24.72 g/m 3 and mean absolute & percentage errors of 18.25 g/m 3 and 23.2%, respectively when compared with in-situ measurements. Subsequently, TSM variability in the Hooghly estuary from the derived TSM maps were analyzed during the period 2003-2018 on monthly and seasonal time scales. Annual cycle of TSM showed peak concentration (> 250 g/m 3 ) during southwest monsoon season which could be attributed to large-scale river discharge as compared to the northeast and inter-monsoon seasons (~100-150 g/m 3 ). Inter-annual variability showed higher TSM during the years 2004, 2012, 2013 and low during 2005 and 2015. It could be concluded that the fine-tuning of existing TSM retrieval algorithm is essential based on long term earth observation data for monitoring the sediment distribution in the coastal and estuarine regions utilizing available satellite observations, particularly in the highly turbid estuaries like the Hooghly estuary.

Remote Sensing Inversion of the Total Suspended Matter Concentration in the Nanyi Lake Based on Sentinel-3 OLCI Imagery

“…The primary drawback of this method is that it is timeconsuming and labor-intensive, making it impractical for conducting long-term, large-scale monitoring[ [4], [5]]. Remote sensing, which is characterized by large spatial coverage, short monitoring cycles, long dynamic time series, and low cost[ [6], [7]], can reveal the migration of pollutants and pollution sources, which is challenging to detect using conventional methods [8]. Therefore, an increasing number of experts and scholars are using remote sensing for the quantitative inversion of TSM to monitor water environments.…”