20-YEAR ASSESSMENT OF TOTAL SUSPENDED SEDIMENT (TSS) VARIABILITY IN BARATARIA BAY FROM MODIS OCEAN COLOR USING A COMBINATION OF ADAPTIVE SEMI-ANALYTICAL AND NEURAL NETWORK ALGORITHMS
Semester of Graduation
Master of Oceanography and Coastal Sciences (SOCS)
Department of Oceanography and Coastal Sciences
Barataria Bay, a hydrologically dynamic basin in the northern Gulf of Mexico, exhibits a distinct spatio-temporal distribution of total suspended sediment (TSS). However, studies on sediment distribution are limited by availability of in-situ data as well as the limitation of ocean color algorithms for suspended sediments in shallow optically complex waters. Barataria Bay TSS concentration profile is complex, influenced in the upper basin by fresh water sources such as the Davis Pond Freshwater Diversion, and in the lower bay by the river plume and marine influence near the mouth of the bay. To efficiently study the sediment dynamics in the Barataria Bay, principal component analysis of long-term field TSS observations identified two major clusters in a region of the bay for which ocean color data were generally available, namely the lower and upper Barataria Bay. In this study, a semi-analytical method based on an adaptive Quasi Analytic Algorithm (AD-QAA) has been used to derive backscattering coefficient at 555nm from MODIS remote sensing reflectance over a span of 20 years (2002 – 2022). Artificial neural network (ANN) algorithm was combined with the AD-QAA processing chain to develop a network with 14 years of in-situ TSS and MODIS-derived backscattering coefficient at 555 nm. The adaptive and flexible nature of ANN predicted long-term TSS in the bay with an accuracy of 73% and 95% in the lower and upper bays, respectively. Further, climatological analysis of TSS showed negligible changes in the lower and upper bays over the study period. The seasonal TSS variation was observed to follow the seasonality of river discharge and wind speed. However, extreme events, such as the high discharge from Davis Pond Freshwater Diversion and cold fronts results in high TSS. Hurricanes can also contribute to high concentration of suspended sediment in the Barataria Bay not only due to effects of high wind and runoff linked to heavy rainfall, but also likely due to hurricane travel speed. Hurricanes making landfall far from Barataria Bay have smaller effect on TSS concentration in the bay.
Sahoo, Bijaylaxmi, "20-YEAR ASSESSMENT OF TOTAL SUSPENDED SEDIMENT (TSS) VARIABILITY IN BARATARIA BAY FROM MODIS OCEAN COLOR USING A COMBINATION OF ADAPTIVE SEMI-ANALYTICAL AND NEURAL NETWORK ALGORITHMS" (2023). LSU Master's Theses. 5758.
D’Sa, Eurico J.
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