Exploring Mangrove Modelling for Coastal Protection

Mangroves are critical to the protection of Caribbean coastlines from the effects of climate change. They act as a natural barrier and buffer, absorbing and attenuating energy on the shoreline during intense hurricanes and storm surges. However, mangroves in the Caribbean are threatened by climate change, unsustainable coastal development, and pollution. For nature-based solutions to deliver on their promise to provide co-benefits for local communities, economies and nature, a wide range of actors must be involved in their research, development and implementation. For coastal engineers, this can look like quantifying the given levels of protection that mangrove forests offer, in order to design and build structures that not only complement the coastal protection they provide, but also support their conservation, restoration and/or rehabilitation.

Four species of mangrove inhabit the Caribbean. They are commonly known as red, black, white and buttonwood mangroves. Red mangroves are typically the most seaward and the first line of defense against hurricanes and storm surges. Their complex network of stilt roots, distinct to the species, are responsible for much of the attenuating capacity that is important to us. Their interwoven root network provides a sturdy yet flexible shield that buffers strong wind and wave energy and holds soil and sediment together.

In order to fully investigate the integration of mangroves into nature-based solutions, we have implemented a series of laboratory experiments using a physical model of the mangroves. Our model is being tested against different wave conditions and water levels to account for phenomena associated with climate change, like sea level rise and storm surges. We designed the mangrove models to scale, using field observations and literature reviews. To create a structure that replicates both the rigidity and flexibility of mangroves, we used a combination of PVC and wire. The roots were secured to an aluminum plate to simulate the anchoring effect of soil. The tests are currently being run in the wave flume in the Coastal Laboratory at the Department of Civil and Environmental Engineering at the University of the West Indies, St. Augustine Campus.

Our preliminary findings indicate that the mangrove models significantly influence wave patterns and sediment distribution, demonstrating the potential of generating guidelines for nature-based engineering solutions. Through a thorough data analysis, we aim to establish clear relationships between the characteristics of mangroves and their effects on wave hydrodynamics and sediment transport. These insights can then be applied to real-world scenarios to predict how existing mangroves might respond to extreme events and design nature-inspired structures that can mitigate the effects of current and future climate change events in the Caribbean. 

See the video for some experimental wave action in the lab!