Characteristics of Sediment in the Inner Shelf Zone of Bangladesh

Author: M. Shahidul Islam, Eshita Akter, Premanondo Debnath, Md. Serajul Islam, Al Artat Bin Ali
DOI: doi.org/10.70279/bmj-v5-i2-1018
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The continental shelf zone of Bangladesh is one of the highest sediment deposition centers of the world. Sediment carried by the vast drainage system surrounding the shelf is widely distributed in the northern part of the Bay of Bengal, where the Swatch of No Ground (SoNG) acts as a triggering factor. In this study, the off-shore bottom sediments from six different locations (around the Bangabandhu Island, SoNG, Nijhum Dwip, Feni river mouth, Meghna estuary and Cox’s bazar) have been used for the analysis of particle size, particle shape, mineralogical properties and bio-markers. It has been found that the distribution of bottom sediments in the northern Bay is distinctive and lead by the land-ocean interface. The western part, part of central zone and eastern part of the shelf is dominated by coarse particles, whereas the greater part of the Meghna estuary is dominated by finer particles. The combined flow GangesBrhmaputra-Meghna rivers through the Meghna estuary is the main source of the coarse sediment influx. These sediments are drift westward to the SoNG. The particle shape shows that the sediments in western part are long-drifted and rich in heavy mineral concentration compare to the eastern part. The sediments in the eastern shelf are short-drifted, possibly derived from nearby hill ranges and/or localized erosion. The bio-marker (diatom) indicates that the greater portion of the Meghna estuary is a unique sediment regime and ecologically very sensitive. This estuarine belt is highly susceptible to marine pollution. However, for sustainable Integrated Coastal Zone Management (ICZM) in Bangladesh, interaction between land and ocean needs to be unraveled connectivity and recording the properties of sediments of the shelf zone could be a good proxy to unveil this links.