Physical Sciences and Mathematics Commons^™

A Numerical Investigation Of Sediment Dynamics In The Northern Gulf Of Mexico In Connection With Hurricanes, Fluid Mud, Climate Change, And Biogeochemical Cycling, Zhengchen Zang

LSU Doctoral Dissertations

Sediment transport and deposition in marginal seas is jointly controlled by many factors including hydrodynamics, fluvial inputs, and the characteristics of sediment particles. This dissertation study employs the coupled ocean-atmosphere-wave-and-sediment transport modeling system (COAWST) to investigate the mechanism of sediment transport in the northern Gulf of Mexico (nGoM) on different temporal scales, as well as its interaction with biogeochemical processes.

First of all, a three-way coupled (atmosphere-wave-ocean) hurricane model reproduced the hydro- and sediment dynamics during hurricane Gustav (2008). Intensive alongshore and offshore currents were simulated on the eastern/western sectors of hurricane track, respectively. High suspended sediment concentration (SSC) was …

Legacy Phosphorus Implications In The Lake Pontchartrain Estuary Sediment Due To The 2011 Bonnet Carre Spillway Opening, Nhan Thanh Nguyen

LSU Master's Theses

Phosphorus (P) is an essential nutrient for life and excess P in aquatic systems can trigger algal blooms. Nutrient-rich Mississippi River water is diverted into the Lake Pontchartrain estuary (LPE) periodically through the Bonnet Carré Spillway (BCS) to avoid downstream flooding to the city of New Orleans, Louisiana and can significantly increase the internal P load in the sediment. A sequential P fractionation procedure was performed on sediments collected before the opening and after the closing of the 2011 BCS operation to understand the role of these large river diversions on P dynamics. Before the 2011 BCS opening, 10,368 Mt …

Incorporating Science-Based Approaches Into The Rapid Assessment Of Wetlands And Streams : Validation, Restoration Trajectory, And Method Development, Jacob Franklin Berkowitz

LSU Doctoral Dissertations

Human alterations within wetlands and streams have resulted in a decrease in ecological functions and associated benefits to society. The scientific literature highlights the functional benefits provided by ecosystems including flood protection, nutrient cycling, and habitat maintenance. Additionally, legislation and regulatory policy require mitigation and restoration as compensation for declines in ecological functions. As a result, the need for practical, repeatable, and technically sound ecosystem assessment methods remains essential to natural resource management. However, few studies determine the validity of rapid assessment approaches by applying quantitative parameters, especially with respect to biogeochemical functions. We assessed biogeochemical functions applied to restored …

Oligohaline Wetland Response And Recovery Following Storm-Driven Saltwater Intrusion In Coastal Louisiana, Whitney Marie Kiehn

LSU Doctoral Dissertations

Coastal ecosystems occupy an interface between land and ocean, making them vulnerable to a variety of natural and anthropogenic disturbances. Large, episodic disturbances (mega-disturbances) cause immediate and long-lasting changes to coastal wetland plant communities and soils by changing the environmental conditions in which they exist. Here I examined the impacts of storm-induced saltwater intrusion and post-intrusion conditions on the structure and growth of an oligohaline wetland plant community, and on wetland soil biogeochemistry and conditions during and after saltwater intrusion. In the greenhouse, a six-week saltwater intrusion reduced canopy cover and species richness. Once intrusion stress was alleviated, plant community …