Posted on February 12, 2025
Louisiana has lost 2,000 square miles of coastal wetlands since the 1930s. It’s become a cliché to say that Louisiana is losing a football field of wetlands every 100 minutes, but the wetlands in Louisiana are key to communities, industry and wildlife in Louisiana.
People live on the land in such places to be as close to their industries like fishing or crabbing as possible. Their families have for generations. As the land disappears, people are displaced and whole cultures and livelihoods are lost.
“If you have a family that crabs or catches crabs for a living, you can’t move them to Thibodaux,” said Rudy Simoneaux, chief engineer for the Coastal Protection and Restoration Authority, based in Baton Rouge. “They cannot as easily do the thing that they made a living doing if they’re living further inland.”
Oil and gas wells and pipelines run under Louisiana’s coast. Birds migrate through the wetlands and stop to rest. The implications of the wetlands disappearing would have national and even international implications.
“This is not a Louisiana problem,” said Nancy Broussard, tour director for CPRA which handles tours for the LSU Center for River Studies. “We just happen to be where the hurricanes hit.”
To combat these challenges, CPRA is working on the Coastal Master Plan, a comprehensive and constantly evaluated plan that works to restore and reduce risk along Louisiana’s coast. To that end, CPRA works in collaboration with the Center for River Studies to conduct research to maintain and restore the coastal wetlands and implement these changes. The center also serves as a way to reach out to the community and train the next generation of engineers, geologists and river experts.
“A significant amount of the south central and southeastern Louisiana coast was formed by the Mississippi River over the last eight to 10,000 years,” said Clint Willson, Dean of the LSU College of the Coast Environment and director of the LSU Center for River Studies. “Once we recognized how important the river was for navigation, for trade, for the economy, we started engineering the river.”
People built levees which prevented the river from flooding its banks, Willson said. This confined the river between those levees and, consequentially, starved the wetlands of nutrient rich water and sediment that would regularly grow and maintain them.
Now, researchers and engineers are trying to use sediment from the river to restore the wetlands and keep them from sinking. In order to do that, they have to understand how the sand moves and how the river behaves to know when and how much sand will be available.
That’s where the Lower Mississippi River Physical Model comes in.
The 90-by-120-foot foam scale model showcases a 14,000-square-mile stretch of the Mississippi River Delta that covers southeast Louisiana from Donaldsonville to the Gulf of Mexico. The model simulates one year of the river’s movement in an hour and is used to test diversions and come up with the most effective solutions.
The next generation
The research is not confined to the work of academics, graduate students and specialized researchers. Students as early as high school can be and are involved.
Through LSU’s College of Engineering’s High School Research Program, Emily Chen, a high school senior at Baton Rouge Magnet High School, worked on research projects at the center. First, she assisted with other people’s research, and then she worked on a project of her own.
Chen’s research project, “Studying the Effects of Distortion on the Hydrodynamics in the Lower Mississippi River Physical Model,” focuses on how accurately the model replicates the river. When scaling the river down, the designers chose to scale the river using different proportions for the river vertically than they used horizontally. The horizontal scale is 1:6000 while the vertical scale is only 1:400.
This is a compromise so the model remains relatively small size-wise while still being able to replicate water flow. However, due to the differences in scale, the model is distorted in some places, particularly in river bends, which means that it might not completely accurately reflect what might happen in the river.
Due to factors like centrifugal force, there will be more or less turbulence because the walls are steeper in the model than they are in real life, Chen said. That impacts the way the water moves in the model and the way that sediment is transported and settles on the model. For example, an experiment might show that sediment settles in a particular place on the model, but due to the distortion, maybe the sediment in the actual Mississippi River would end up somewhere else, or there might be less of it.
Chen’s project, carried out in 2023, tracked water movement in the model using little floating spheres coated with glow-in-the-dark paint. She hopes that her research can be used to develop and optimize future experiments on the model.
“Learning about the coastal restoration research going on at the center really showed me the urgency of our state’s environmental needs, which helped fuel my passion for my research,” Chen said. “This experience, along with other research opportunities, has encouraged me to think more open-minded and interdisciplinary about science, which I plan to use in my research endeavors after high school.”
Recently, Chen’s work was recognized as a Regeneron Science Talent Search scholar. She was selected as one of the top 300 candidates from nearly 2,500 entrants from 795 high schools across 48 states; American Samoa; Guam; Washington, D.C.; Puerto Rico and 14 other countries.
“We have more confidence that the model is reproducing some of the complexities that occur in the actual river,” Willson said when asked about the implications of Chen’s research. “We have more confidence in the way the water flows and what happens when we divert water out of the Mississippi River.”
According to Willson, having younger students collaborate on research is helpful for training and teaching but also because students with shorter timelines (like a summer) are more intentional about having their projects done. They often ask questions that others might not.
Coastal Master Plan
On the engineering side, the engineers take the research that is done at the center and use it to design projects, facilitate permitting and obtain contractors.
“ Our planning and research division never really stops working on a master plan,” Simoneaux said. “As soon as one’s released, they’re already starting to look into ‘How are some of those projects performing? What could we do differently? What worked, what didn’t work?’”
According to Simoneaux, the team does a lot of dredging, bringing sediment from one part of the coast to another, building new levee systems/barrier islands and repairing parts of the coast that are severely impacted by hurricane damage.
”We do have a couple active diversions at Davis Pond and Caernarvon where we are using the fresh water from the river,” Simoneaux said. “These are areas of the marsh that were dying that have come back a lot since we’ve had these projects that we’ve actually been able to restore and recreate some wetlands using these diversions.”
