The Sundarbans National Forest (SNF), located on the modern topset of the Ganges-Brahmaputra-Meghna (GBM) Delta, is the world's largest mangrove stand (~10,000 km²), and provides a wide range of cultural, environmental, and economic benefits to the nation of Bangladesh. At present, sediment accretion in the SNF occurs at a rate comparable to that of the locally accelerated sea level rise (~1.1 cm yr^-1), despite substantial modification of the regional sediment dynamics resulting from the construction of channel embankments. As ~50% of the sediment deposited in the SNF each year is recently delivered (<6 mos) from the GBM, the threat of a reduction in sediment suppy as a result of water and sediment diversions associated with India's National River Linking Project raises concern over the SNF's continued sustainability. Here, we examine: 1) the capacity for short-term sediment storage within tidal channels of varying dimensions, and 2) the hydrodynamic conditions responsible for resuspending this material and delivering it to the mangrove platform. We compare textural and radiochemical characteristics from short cores (< 50 cm) collected along the intertidal channel banks, with those from the mangrove platform, to assess seasonal storage of GBM sediment within tidal channels, and the timeframe of its delivery to the SNF platform. We also present instrument data from multiple locations within a confined basin of the SNF, using an upward-looking acoustic Doppler current profiler, pressure sensors, and optical backscatter sensors, to document how transport conditions change with distance away from the primary inlet, and away from the nearest tidal channel. This collection of physical and instrumental observations is then compared to an existing dataset of platform deposition rates, allowing us to address the threat of a reduced sediment supply to this region, as well as the capacity for this system to self-supply sediment to the platform.

Rip Hale is an assistant professor in the Department of Ocean, Earth & Atmospheric Sciences at ODU. His research focuses on sediment transport and deposition in coastal areas, relying on field data from acoustic and optical instrumentation and sediment cores. He is actively seeking M.S. and Ph.D. students interested in this type of research.

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