Semester of Graduation

Summer 2025

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

Barataria Bay, Louisiana, USA exhibits a unique microtidal, wind-driven hydrodynamic climate where extensive levee infrastructure throughout Louisiana has starved Barataria Bay and similar interdistributary bays of the historic levels of terrigenous sediment import. This has contributed to extreme coastal wetland loss in Louisiana. This project seeks to understand how hydrodynamic and meteorological conditions are linked to sediments’ fate after erosion from the marsh edge. Specifically, this project seeks to differentiate the roles of wave resuspension and marsh edge erosion (MEE) in sediment dynamics in Barataria Bay. An acoustic wave and current profiler (AWAC) was used to capture hydrodynamic conditions, and the acoustic backscatter from the AWAC was used to quantify suspended sediment concentration (SSC). The wave parameters from the AWAC were then used to calculate bottom shear stress and estimate sediment resuspension. Additionally, Sentinel-2 imagery and the normalized difference turbidity index were used to quantify marsh edge erosion by identifying zones of high turbidity (ZHTs) originating from the marsh edge, and wind data was taken from the ERA5 reanalysis dataset. When wind speeds exceed 5 m/s a regime shift in the mechanism suspending sediment occurs. During quiescent conditions (wind speed < 5 m/s), resuspension is low, and most SSC is likely due to advection from the Gulf Intracoastal Waterway and the mouth of the Mississippi River. When wind speed exceeds 5 m/s, both resuspension and the size of ZHTs scales with wind speed. This pattern is especially apparent in periods of northerly winds, while southerly winds do not exhibit the same regime shift. While ZHTs were intended as proxies for MEE, a quantitative link between ZHTs and MEE was unable to be established. Rather, ZHTs were visually traced to the marsh edge, and links between wind conditions and ZHTs were established. However, the significance of these relationships is limited due to the small number of images analyzed. This work demonstrates the way meteorological and hydrodynamic conditions lead to marsh edge erosion and sediment transport.

Date

7-23-2025

Committee Chair

Hiatt, Matthew

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