We are evaluating the performance of three types of nature-based solutions: oyster reefs, coral reefs, and wetlands created from dredged sediments. We will examine project sites five or more years after their implementation to understand the benefits they provide and how those benefits change over time as the sites mature and evolve. Understanding the long-term performance of nature-based solutions is key for site selection, design, and maximizing the benefits of future projects.

The project team is evaluating the long-term performance of three types of nature-based solutions: oyster reefs (top), coral reefs (middle), and wetlands created from dredged sediments (bottom). Credit: NOAA.

Why We Care
Nature-based solutions for coastal protection, such as wetlands, dunes, islands, coral and oyster reefs, are approaches to erosion and flood control that mimic nature, unlike traditional approaches, such as bulkheads and levees. Nature-based solutions have additional benefits that these "hardened" traditional approaches do not, including: improved water quality, improved habitat quality, enhanced recreational opportunities, and the ability to self-repair after storms and adapt to changing sea levels.

An obstacle to widespread use of some nature-based solutions is the uncertainty of how they will evolve and perform over time. Understanding the ability of nature-based solutions to provide the intended benefits in spite of storms, sea level rise, and other environmental stressors is critical to designing the nature-based solutions of the future and to their widespread acceptance and use.

This project will evaluates the long-term performance of three types of nature-based solutions (coastal wetlands restored through beneficial use of dredged sediments, oyster reefs, and coral reefs). Understanding the range of environmental conditions under which each nature-based solution provides long-term coastal resilience benefits is a primary project goal.

What We Are Doing
This project focuses on nature-based solutions projects constructed more than five years ago and that have "as-built" surveys or preliminary monitoring data available for comparison to present conditions. We will use a combination of hydrodynamic modeling, remote sensing, and on-the-ground data collection to evaluate the performance of these projects post-implementation.

Specific parameters measured may include plant/coral/oyster abundance and cover, nature-based solution footprint/dimensions, shoreline position, and surface topography. Environmental conditions to be investigated include wave exposure, water depth, tidal range, sediment characteristics, and adjacent habitats. We aim to select a few project sites within multiple systems and regions to provide some system-level consistency for performance evaluation, while providing a broader range of explanatory variables (e.g., tide range) when comparing performance across systems. Specific projects, indicators, and monitoring metrics will be selected through discussions with stakeholders and end users (e.g., NOAA Restoration Center, US Army Corps of Engineers, state coastal zone managers).

Benefits of Our Work
This project fills knowledge and data gaps on long-term performance of three nature-based solutions approaches. Project results will be useful for designing, permitting, and installing nature-based solutions projects that are more likely to improve an area’s long-term resilience to flooding and erosion, water quality, and habitat quality.

Next Steps
This project is conducted in three phases, one for each nature-based solutions type investigated.

• Phase 1: Beneficial Use (2022–2025) — Texas and Maryland
• Phase 2: Oyster Reefs (2023–2026) — TBD
• Phase 3: Coral Reefs (2024–2027) — TBD

Multiple products will be developed for each phase (type of nature-based solution):

1. Decision Support Tools such as guidance documents to inform design, siting, and evaluation
2. Spatial and Visual Project Inventory to highlight findings, lessons learned, and explore project data
3. Monitoring Guidance on the development of monitoring and adaptive management to further understanding of nature-based solution performance and reduce negative outcomes
4. Publicly accessible data