Mangrove trees are an essential mitigating force against storm surges that plague subtropical and tropical coastlines. Along with their high salt tolerance, mangroves filter and balance incoming saltwater immersions. Capable of sequestering carbon dioxide up to five times greater than the typical terrestrial forest, mangroves use their in-built quality to collect sediment and adjust surface elevation when fluctuating sea levels erode higher ground.
Understanding the impacts of fast-depleting mangroves, and with those the compromised ecosystems and habitats for flora and fauna, two creative teams have proposed hybridized forms to address these challenges. Here, we look at each innovative solution and examine how they aim to solve the issue of storm surges in unique ways.
From rendering to reality: APTUM’s pontoon-like concrete forms are designed to serve as breakwaters and reintroduce mangroves along the coast of Colombia.
Isla Rhizolith / Rhizolith Islandby APTUM Architecture
A partnership spearheaded by APTUM with CEMEX Research Group and Syracuse University architecture students resulted in an experimental project of floating concrete islands to reintroduce mangroves along the Port of Cartagena, Colombia. The floating structure is a root system encased in mineral matter, created through processes of weathering, decomposition and cementation. Serving as breakwaters, the structure is composed of two parts: a “head” and a “fin.”
Images via APTUM
Cast in a light concrete mix to allow floating, the head is outfitted with voids to account for lateral growth. The “fin,” as the base is cast in denser Ultra High Performance Concrete (UHPC), with its stability and in-laid voids promotes habitat opportunity for other species. The Rhizolith relies on its material porosity and its floating form to diffuse water force.
Images via APTUM
Eventually the structures anchor themselves into the seabed when they reach full maturity, envisioned to take five to 10 years. To aggregate along the shore, the Rhizolith island uses ropes to wrap through the steel grommets embedded in the rubber ring of the head.
TetraPOT by Sheng-Hung Lee & Wan Kee Lee
Lee+Lee created a synthesized form that exploits the strengths of natural and man-made coastline defense systems after noting the failure of Tetrapods. The form takes after the Tetrapods, the four-legged concrete structures that occupy many coastlines. The “TetraPOT,” composed of concrete, organic materials and plants, strategically hollows out the tetrapod to hold a decomposable pot and allow mangrove roots to spread outward.
Mangrove root growth occurs when rising tides seep into the decomposable pot. The lateral root growth then begins to intertwine with neighboring TetraPOTs, holding the form in place and creating a structured sea defense web. The TetraPOT also supports habitat for other species while improving air and water quality.
Images via Sheng-Hung Lee
The “Rhizolith” and “TetraPOT” offer compelling takes on coastline defense. Ideologically and materially, both concepts create stable hybrid structural forms and support habitat for other living species. The most significant distinction between the two is their form and structural inner workings.
The Rhizolith, unlike the TetraPOT, takes into greater account the mangrove’s stress risk of too-high waters by introducing floating components. Additionally, while the TetraPOT permanently combines the mangrove encased into the concrete form, the Rhizolith intends for the mangroves upon full maturity to break through the concrete, creating a purely natural defense.
