Sediment Transport Processes in Shallow Receiving Basin: A Case Study at Barataria Bay, Louisiana, USA

Guandong Li1, Kehui Xu2,3, Samuel J Bentley4,5, Yanxia Ma6, Z. George Xue2 and Robert Bales2, (1)Tulane University, New Orleans, LA, United States, (2)Louisiana State University, Oceanography and Coastal Sciences, Baton Rouge, LA, United States, (3)Coastal Studies Institute, Baton Rouge, United States, (4)Louisiana State University, Geology and Geophysics, Baton Rouge, LA, United States, (5)Coastal Studies Institute, Baton Rouge, LA, United States, (6)Louisiana State University, Baton Rouge, LA, United States
Eustatic sea level rise, insufficient sediment supply, and local subsidence are the most powerful factors impacting drowning coastal areas around the world. To overcome such land loss issues, sediment diversion is proposed as an efficient way to reintroduce sediment-laden river water to adjacent shallow receiving bays and build new land. Hence, background studies and understanding the physical settings of shallow receiving basins is critical for successful implementation of sediment diversion. This study deployed two tripods as observation platforms from December 2018 to May 2019 at Barataria Bay, the receiving basin of the Mid-Barataria sediment diversion - one of the largest sediment diversion projects globally. Four sensors were deployed on each tripod, including OBS (Optical Backscatter Sensor) 3A, ADV (Acoustic Doppler Velocimeter) Ocean, seabird HydroCAT-EP, and wave gauge. Tripods were deployed in the northern and southern sites of Barataria Bay and collected data for two observational periods: December 2018-February 2019 and March-May 2019. Sediment dynamics, hydrodynamics and their impacts on dissolved oxygen concentration were studied using measured suspended sediment concentration, salinity, temperature, turbidity, dissolved oxygen, wave and current data, in conjunction with meteorology data from NOAA station. During the frequent cold fronts season (December 2018-February 2019) strong northerly wind led to increased wave height, bottom shear stress, turbidity and oxygen. Meanwhile, temperature and salinity decreased during these periods. After the passage of cold fronts, salinity increased gradually due to tidal mixing with salty water. While weak diurnal tides are the dominant tidal pattern in Barataria Bay and the role they play in sediment transport cannot be ignored. These observations indicate tides might be more important than wind-driven waves. Observational data collected in March-May 2019 reveals less frequent passing of cold fronts and lower salinity in both stations which most likely due to estuarine freshening by Mississippi River flooding in spring 2019.