Sediment Dynamics in a Vegetated Tidally Influenced Interdistributary Island: Wax Lake, Louisiana

River deltas are maintained by a continuous supply of terrestrial sediments that provide critical land-building material to help sustain and protect coastal communities. In order to examine the mechanisms of sediment delivery, a field study was conducted at Wax Lake Delta WLD located in St. Mary Parish, LA. Instrumented platforms equipped with wave, current, tide and sediment sensors were installed on Mike Island, an interdistributary island located near the centerline axis of the delta complex. This report focuses on the hydrodynamic measurements, which imply multiple regimes of sediment delivery based on seasonal differences in climate and biological activity. In winter, vegetation is absent, and the primary flow is driven by tides. In the spring, increased river discharge inundates the island producing lateral flows and increase in suspended sediment concentrations that supply large quantities of terrestrial sediments to interior regions. In late spring, persistent southeasterly winds create setup along the coast and higher water levels over the island allowing waves to more easily penetrate the island interior. The emergence of American lotus Nelumbo lutea in summer forms a dense canopy over the island reducing wave and current energy, increasing the potential for sediment deposition.