Wind-induced bottom sediment resuspension in a microtidal coastal environment

Bottom sediment resuspension frequency, duration, and extent (i.e. areal percent of bottom sediments affected) were characterized for the 15 month period from September 1995 to January 1997 for select water bodies within the Barataria Basin, Louisiana, USA. An empirical model of sediment resuspension as a function of water depth, wind speed, direction, and fetch was derived from surface gravity wave theory. The model was validated with water-column turbidity imagery obtained from visible and near-IR AVHRR data. Based on model predictions, wind-induced resuspension occurred during all seasons of this study. Model predictions of the critical wind speed required to induce resuspension indicate that winds of 4 m s−1 (averaged over all wind directions) resuspend approximately 50% of bottom sediments in the water bodies examined. Winds of this magnitude (4 m s−1) occurred for 80% of the time during the late fall, winter, and early spring and for approximately 30% of the time during the summer. More than 50% of the bottom sediments, on an areal basis, are resuspended throughout the year, indicating the importance of resuspension as a process affecting sediment and biogeochemical fluxes in the Barataria Basin.