Flow distribution and sediment transport mechanism in the estuarine systems of Ganges-Brahmaputra-Meghna delta

Abstract

The Ganges-Brahmaputra-Meghna delta is one of the most dynamic tide dominated deltas in the world, a dynamism forced in part by the huge flows and sediments generated in the catchments of the GBM basins. In this study, we apply 1D and 2D dynamic models (HEC RAS and Delft 3D) to analyze the volumetric flow distribution in these estuarine systems. The flow distribution parameters are then used as proxy variables to study the sediment transport mechanism in the region. Flow distribution patterns show that freshwater input and storage are much higher than the saltwater input and storage. Considering freshwater contribution, eastern estuarine system plays important role during monsoon whereas, during dry season it is central estuarine system. Western estuarine system mainly contributes to store saline water. The Lower Meghna estuary is the main flow and sediment carrying channel in the region. Clock-wise estuarine circulation makes the sediments to re-enter from the sea into central estuarine system, forms flocks in the saline environment, and cause sedimentation .