Environmental Impacts of Developing Flood Protection Systems throughout a Marshland Ecosystem in Lower Louisiana: a Numerical Case Study

Louisiana is a state in the United States of America that is experiencing the multiple challenges of climate change, extreme weather events (such as hurricanes), and human intervention impacts for flood protection. The marshland regions of lower Louisiana have been heavily impacted by human influence, since the state was originally formed and maintained by deposition of sediment carried from the Mississippi River. Not only has impact of human intervention impacted the sediment transport processes, but there has also been significant human development of levee systems and other flood protection structures in Louisianas coastal environment. Specifically after Hurricane Katrina, additional levee systems, environmental control structures, and floodgates were built in this marshland region. A few different design criteria are important to analyze for these systems, some of the more notable design criteria are flood protection, navigational safety for ships passing through floodgates, marshland protection, water quality, and system biology. In addition to monitoring human impacts, the US Army also seeks to understand how the system behaves under long-term climate change impacts. While flood protection is a primary motivator for building these systems, it is important to ensure that structures built do not have adverse effects on the local wildlife or commercial/recreational opportunities for the locals in these areas. Adaptive Hydraulics (AdH) is a finite element based 2D shallow water equation solver that can be used to numerically evaluate these impacts. Another focus of this study is to analyze the indirect impacts of structures built since 2004. To ensure that everything built since then has not had major impacts on the local wildlife or commercial/recreation opportunities, AdH and PTM can also be used to gain insight into that impact. The numerical modelling portion is the authors direct contribution to the project, though the overall project of developing Lower Louisiana, and its impact of that and climate change on the natural environment and local people will be discussed.