A network of climate-resilient vegetation mats could be coming to Boston Harbor. Here’s how the shoreline would look if The Emerald Tutu is implemented.
The Emerald Tutu is an artificial “floating marsh” that would protect East Boston from sea- level rise and storm surges as the climate warms. This innovative resilience project, proposed by MIT’s Climate Changed series, focuses on designing nature-based infrastructure. With a focus on human and non-human coastal communities, the Tutu is designed to solve a host of problems that plague traditional coastal engineering.
The Problem With “Hard” Coastal Engineering
Boston already experiences some of the worst high-tide flooding in the nation. If carbon emissions continue to be released at their current pace, flooding is projected to worsen. Boston’s sea level is estimated to rise 9 inches by 2030, and more than 3 feet by 2070. This kind of change would worsen storm surges, threaten drinking water with salt-water intrusion, and displace countless residents.
But, thus far, solutions have relied heavily on “hard” infrastructure like concrete seawalls, designed to withstand severe wave action and storm surge. In recent years, these structures have proven to be ineffective and harmful both ecologically and economically.
Seawalls multiply the force of waves onto nearby shorelines, thereby accelerating erosion elsewhere. Smooth, featureless surfaces also make it hard for marine life to grow on and around hard infrastructure.
The “Soft” Solution
Coastal wetlands like marshes are known to protect communities near the shore, soaking up and dispersing energy from waves. The design of the Tutu mimics this natural phenomenon.
The Tutu is a circular network of “mats” that together act as a buffer between the shoreline and incoming ocean waves. Each mat can absorb wave energy and protect about one foot of shoreline—a number that increases when the many mats are interconnected. Floating mats are interlinked and anchored to the seafloor to provide “protective canopies” that encircle the urban coastline. These canopies are seeded with above and below-water plants: marsh grass above and seaweed below. The submerged vegetation impedes the inland rush of tides, known as storm surge. These factors add up to reduce inland flooding during storms. As an interconnected system, the mats absorb and transfer energy through the network, acting to disrupt these large incoming waves.
The manufactured materials used in concrete seawalls will degrade and weaken over time; hard materials reflect incoming energy and break under extreme force. But living materials strengthen over time and self-renew. Such “soft” materials are flexible and absorb energy. They’re biodegradable too, which means materials like coconut fiber, wood chips, and burlap canvas will be harmless if they become dislodged.
Like pieces of a puzzle, the mats would allow designers to add and subtract sections of the network that protect the shore. The floating design makes the Tutu ideal for deployment in areas where high real estate values coastal resilience projects difficult. Offshore walkways would weave through the mats, adding more recreational green space to East Boston.
What Is The Tutu?
The name “Emerald Tutu” references the “Emerald Necklace”: a series of connected park systems in greater Boston. The Emerald Necklace was designed by legendary landscape architect Frederick Law Olmsted in the late 1800s. Olmsted, who designed Central Park, envisioned a radically collective space where residents could have public space to enjoy, while bringing nature back to the city. As systems, these parks solved major drainage challenges of an industrializing city, integrated transit, and balanced residential development.
“The spirit of the Emerald Tutu is to re-imagine what public infrastructure can do for citizens,” says Gabriel Cira, the project lead of The Emerald Tutu. “To address the true danger of climate change in Boston, we wanted to focus on making infrastructure green, inhabitable, and accessible, rather than reinforcing the division and erasure that Boston’s major infrastructure initiatives of the 20th century brought.”
Deploying the Emerald Tutu
The Tutu is a collaborative project between landscape architects, coastal engineers, climate scientists, and water resource specialists. Together, project leaders can study flood mitigation and its relationship to ecological and social co-benefits with coastal communities. The goal for the project is to find a solution that’s flexible, inexpensive, non-invasive, and enjoyable for the public.