A remote sensing approach to ascertain spatial and temporal variations of seawater quality parameters in the coastal area of Bay of Bengal, Bangladesh

Abstract

Sea surface temperature (SST), surface chlorophyll (SChl), Sea surface salinity (SSS), and total suspended solids (TSS) are some critical seawater quality parameters (SWQP) in the Bay of Bengal (BoB) of Bangladesh. The research objectives were to investigate the distribution of SST, SChl, SSS, and TSS in the Summer and Winter seasons of 2014, 2018, and 2020 and denominate the spatial and temporal variation of these parameters in the BoB. The MODIS-Aqua, VIIRS-SNPP level-3 ocean color, and Landsat 8 OLI-TIRS multitemporal images were used and the Geographical Information System (GIS), and Remote Sensing (RS) techniques were applied for interpreting and mapping the output. The results asserted that temporally in the Summer season SChl and SSS increased by 11.02% and 7.96% respectively and TSS decreased by 14.25% from 2014 to 2020. On the other hand, in the Winter season, SST and SSS decreased by 3.37% and 3.38% respectively and SChl and TSS increased by 2.32% and 70.95% respectively from 2014 to 2020. Besides, in the Summer season, the maximum values of SST, SChl, and TSS were 30.16 °C, 2.61 mg/m3, 268.45 mg/l respectively and in the Winter season, the maximum values were 25.06 °C, 2.93 mg/m3, 192.31 mg/l respectively. Spatially, all the maximum values of SST, SChl, and TSS were concentrated in areas near the coastline. Contrary, the maximum values of SSS were 29.01 ppt and 31.21 ppt in the Summer and Winter seasons respectively and both values were coagulated in the open sea area. Seasonally, The SST and TSS were higher in the Summer season and SChl and SSS were higher in the Winter season for all the years in the BoB.