Numerical Modeling of Tidal Dynamics and Transport in the Multi-channel Estuary of the Mekong River

<span">The Mekong estuary is an area of high biodiversity in which the ecosystem has been influenced not only by natural factors but also by anthropogenic impacts (Quang et al., 2010). The former determine the water circulation such as tide propagation, river discharge and outflow plume behavior, while the latter consist of full-dyke systems in the flood zone, saline protection systems along the coast and in general much reduced mangrove forests along the river banks and coasts. These factors influence the coastal system directly and indirectly by changing the sediment dynamics. This study aims at understanding the tidal characteristics of this multi-channel estuary by simulating the water circulation and investigating impacts of tidal forcing on the flow regime. In order to achieve these objectives, a process-based approach by using Delft3D Flexible Mesh is applied to calculate the water regime in the delta. In addition, the model has been calibrated and validated through comparison of simulated and observed tidal harmonics during different discharge stages. The results show a good agreement between simulation and observation. The model will be used to understand the system-wide sediment dynamics in all the main branches of the tide-influenced Mekong delta, from Kratié in Cambodia to the East Sea shelf. An overview of the grid is given in the attached figure. The model includes a large stretch of shelf to enable studying the seasonal plume characteristics and is driven by astronomical boundary conditions at the seaward boundary and imposed discharges at Kratié; the Tonle Sap lake in Cambodia is included as it exerts a strong control on the upstream water levels.

Acknowledgements: This study was funded by ONR under Grant N00014-12-1-0433 Modeling the Mekong Delta at three different scales