Natural defenses: UF researchers use living infrastructure to protect Florida’s shores

Armed with a $7 million grant from the Army Corp of Engineers, University of Florida researchers are working to bolster shoreline resilience and restore troubled wetlands in St. Augustine through nature-based solutions.

“The idea of nature-based solutions is to build what we sometimes refer to as green infrastructure, to use living, natural components as the building blocks,” said Andrew Altieri, Ph.D., an assistant professor with the Engineering School of Sustainable Infrastructure & Environment and interim director of the Center for Coastal Solutions, also known as CCS.

Instead of building man-made structures to protect wetlands, for example, restoration crews can move dredged natural sediment otherwise destined for costly disposal to increase wetlands’ size and elevation, restoring their ability to protect shorelines from storm surge, keep pace with sea-level change, filter toxins, store carbon and provide habitats for wildlife. 

The project is in concert with the Army Corps of Engineers’ goal to naturally reuse and repurpose at least 70% of dredged sediment into other natural areas to benefit habitats and restoration by 2030.

“It is critical to understand, test and model how natural processes can be harnessed and strategically implemented to sustainably meet the challenge of rapidly intensifying coastal hazards while also providing environmental, economic and social benefits,” Altieri wrote in the project’s technical summary.

Overall, the multi-disciplinary project closely examines patterns and processes of change in coastal landscapes. That includes wetlands — marshes and mangroves — and beach/dune systems.

The project comes as these coastal areas are facing threats both natural and human. These areas are essential to wildlife, air quality, native vegetation, storm protection and the overall health of the ecosystem. A 2008 study by the U.S. Fish and Wildlife Service reported a net loss of about 361,000 acres of wetlands in the coastal watersheds of the eastern United States between 1998 and 2004 — an average net decrease of 59,000 acres each year, with experts citing sea-level rise as one of the primary factors.

“We're trying to understand the patterns of that loss and what's leading to it,” Altieri said. “These systems are essentially the first and sometimes last line of defense against coastal hazards, risks that include storm surges and coastal flooding. They are forming a buffer, this kind of protective layer on our coast. But they're changing, generally for the worse and are in danger of being lost.”

With this project, the CCS-led research team plans to advance the science, technology and engineering principles of nature-based solutions.

With marshes, the primary concern is elevation loss, which can drown the vegetation critical to the ecosystem. They are sinking, eroding and succumbing to sea-level changes, Altieri said.

“The plants are really important for trapping sediment and holding sediment,” he said. “You lose some of the plants, then you get more erosional loss and a lack of the accumulation of sediment.”

Sediment is natural muck on the bottom of water bodies.

“If we can add sufficient sediment to increase the elevation to a level where the plants thrive, then they will retain that sediment that's been added to hopefully trap more sediment and accumulate more biomass through their growth,” Altieri said. “It’s something that may need to be done periodically. You may stop that decline, but you may even reverse the process of loss and change the trajectory.”

As a bonus, this process saves the cost of disposing of dredged sediment, which is usually piped offshore or to a materials-management area.

This project is the next step for CCS-led coastal resilience efforts in St. Augustine. In 2024, CCS and WSP Environment & Infrastructure Inc. launched a coastal wetlands-restoration project to keep pace with sea level change and erosion. The 2025 work is a standalone project with separate funding, Altieri said.

The current project also has more research disciplines and project partners, including UF researchers from Landscape Architecture, Geological Sciences and the School of Forest, Fisheries and Geomatic Sciences.

“Storm surges, wave energy, coastal flooding – all of that can be slowed or reduced because of wetlands,” Altieri said. “They are basically like shock absorbers. These wetlands, beaches and dunes can be lost or eroded to some degree, but the upland area behind them is essentially protected.”

Researching the resilience of dunes comes with a different set of dynamics. Here, they are looking at the plants that support the dunes – sea oats and panic grass, for example. That vegetation also provides a habitat for animals such as beach mice, turtles and birds.

On the beach, the team also is looking at water energy and how grain size affects the stability of dunes.

“It’s understanding water movement, water energy. How is that interacting with depositing sediment, moving sediment around, sorting sediment? With water, you tend to carry finer particles further than coarser materials,” he said.

What does success look like after the award’s five years end?

“We'll have an understanding of what's changing on our coasts and why,” Altieri said. “We'll have an understanding of how we can work within this system to modify the natural components and utilize the natural processes. And we will hopefully be working with partners through additional funding mechanisms to actually apply that towards implementation of solutions to increase coastal resilience.”

The team also includes Peter Adams, Department of Geological Sciences; Julie Bruck, Department of Landscape Architecture, School of Landscape Architecture and Planning; Maitane Olabarrieta, ESSIE; Alex Sheremet, ESSIE; Nina Stark, ESSIE; Ben Wilkinson, Geomatics Program, School of Forest, Fisheries, and Geomatics Sciences; and Xiao Yu, ESSIE.