The Emerald Tutu: A Man Made Marsh On Track To Be Built In Boston

Band Of Green Space Around The City Will Protect It From 3 Feet of Ocean Rise by 2050 and Extreme Flooding.

Northeastern University assistant professor Julia Hopkins is helping develop interconnected rings of floating wetlands to stave off flooding of coastal cities like Boston for a startup called the Emerald Tutu. Two of the circular mats are already in the water and a third is set to launch this year. Like land-based parks, the Emerald Tutu is designed to feature walkways that get people out in nature—in this case out on the shallow waters of coastal shorelines.

But in addition to being aesthetically pleasing and recreational, the Emerald Tutu would absorb wave energy and help ameliorate the flooding that increasingly threatens to inundate Boston and other coastal cities. “It functions as a marsh without being a marsh,” says Hopkins, who specializes in civil and environmental engineering and is lead scientist for the Emerald Tutu startup. The circular mats that make up the components of the tutu are about seven feet in diameter and are designed to have marsh grasses growing on top and seaweed below.

“They are like a sponge. They absorb wave energy,” Hopkins says.

“The basic idea takes some of the theory we have about how nature is supposed to be protecting shore and applying that to something we can use in urban environments,” Hopkins says in a Northeastern University College of Engineering article. The Emerald Tutu project was developed by Hopkins and other collaborators, including architect and Tutu project leader, Gabriel Cira, and Northeastern alumna Louiza Wise. It received a Small Business Innovation research grant from the National Science Foundation in 2020 to develop the floating wetlands.

Hopkins, who has tested mats in the massive wave energy basin at Oregon State University, deployed the Emerald Tutu’s first mat off a pier in East Boston in the spring of 2021. Made up of biodegradable material such as coconut fiber, wood chip byproduct, burlap canvas and marine-grade rope, the mats won’t pollute the environment if they break loose and are lost at sea, Hopkins says. The completion is scheduled for 2026.