2019 CSDMS meeting-056


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Seasonal variation in wave-driven sediment resuspension in the northern Andaman Sea: Results from a numerical model

Courtney Harris, Virginia Institute of Marine Science Gloucester Point Virginia, United States. ckharris@vims.edu
Matthew Fair, Virginia Institute of Marine Sciences Gloucester Point Virginia, United States. mjfair@vims.edu

Much of the estimated 600 Mt of river sediment annually carried by the Ayeyarewady and Thanlwin River system (Myanmar) is delivered to the northern Andaman Sea. This area is influenced by strong tides, monsoon conditions, and periodic cyclones; however the processes that dominate dispersal of riverine material in the coastal ocean of this system have remained largely unquantified. The shelf exhibits a dramatic asymmetry of the surface morphology and sediment texture in the east – to – west direction, and recent field observations indicate that sediment accumulation rates increase toward the west. To explore the role that wave resuspension may play in these patterns, the SWAN (Simulating WAves Nearshore) model was implemented for the northern Andaman Sea, and run to represent both winter and summer time periods. The wave orbital velocities provided by SWAN were then analyzed to estimate the frequency of resuspension of fine-grained sediments throughout the study area. Results showed that wave-driven resuspension is much more frequent during the summer conditions which are characterized by the southwest monsoon; compared to during the northeast winds typical of the winter season. Additionally, the area fronting the Ayeryarwaddy Delta is subjected to energetic waves throughout both the summer and winter conditions, but wave energy decreases dramatically eastward toward the Thanlwin River mouth.