Effect of wind, river discharge, and outer-shelf phenomena on circulation dynamics of the Atchafalaya Bay and shelf

The influence of wind, river discharge, and outer-shelf variations on the circulation of the Atchafalaya Bay and the adjoining inner shelf were examined using a 3-dimensional circulation model. Current and water level data from three stations along a transect off the Marsh Island were used for model calibration and skill assessment. Coastal current and its spatial distribution were significantly affected by open boundary conditions. Model sensitivity analysis suggested that the vertical eddy viscosity has a substantial impact on the energy and momentum transfer across the water column in this shallow bay-shelf environment. It was also shown that westward to northwestward currents dominated in the study area during the non-summer months and that would transport westward large volume of sediments discharged from rivers during the spring flood season. This sediment load is contributing to the progradation of the Chenier Plain along the southwestern Louisiana coast. A particle tracking Lagrangian model validates the westward migration of suspended sediments originating from the river mouth area during the spring season.