Landscape Design to Improve Coastal Resilience

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This bioswale is a natural landscaping method to slow and filter stormwater runoff from a roadway. Rhode Island communities are exploring natural methods not only to treat runoff, but also to improve coastal resilience to storms, erosion, and sea level rise. Photo by Aaron Volkening.

Three Rhode Island communities will serve as new pilot projects to increase coastal resilience to climate change impacts, such as sea level rise, flooding, and increased storminess.

The project will explore landscape methods that are natural – or that mimic nature – to restore ecosystem services (habitat and stormwater filtration, for example) to developed areas.

The project, funded by the National Fish and Wildlife Foundation and the U.S. Department of the Interior, is led by Pamela Rubinoff and Teresa Crean, extension specialists with the URI Graduate School of Oceanography’s Coastal Resources Center and Rhode Island Sea Grant. It will look at how green infrastructure, typically used to reduce and treat stormwater, could be used in coastal areas in Newport, Warwick, and North Kingstown, to aid those municipalities’ efforts to make their communities more resilient. The project kicked off with a meeting on April 16 with project partners.

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Caitlin Chafee describes how sea level rise is affecting a Rhode Island salt marsh. Photo by Meredith Haas.

Caitlin Chafee, policy analyst for the R.I. Coastal Resources Management Council, described some of the challenges of landscape design and development in coastal area. “One of the most obvious is you are on the shore, you’ve got sea levels, tides, coastal storms, elevated water tables – this is a situation that is not going to get any better with climate change and sea level rise,” she said. “This is something we have to consider when we are … choosing our designs.”

And, she added, “Our coastal areas are some of the most densely developed. There’s not a lot of open space to work with.” She pointed out that coastal areas are also economic engines for their communities and the state, so how projects will impact economics is also a consideration.

Jamie Houle, program manager for the University of New Hampshire Stormwater Center, said that investments in landscaping should aim to serve multiple functions that have economic, environmental, and social benefits. He talked about a project at Berry Brook, a 185-acre watershed in Dover, New Hampshire, where 30 percent of the watershed was covered in impervious surfaces (e.g., roads, buildings, parking lots), and where water pollution was a significant problem. The project, which has been underway for over four years, has reduced the impervious area to 15 percent through numerous projects including widespread installation of raingardens, constructed wetlands, tree filter rainbarrels and stream “daylighting” (removing hard surfaces over the stream, or redirecting the stream back above ground).  The project is continuing this spring with a goal of reducing impervious cover to 9.5 percent. While the cost of the project is estimated to be $1.2 million, paid for through a series of grants from the New Hampshire Department of Environmental Services, at least an equal amount has been contributed by the city via matching funds.  A related triple-bottom-line assessment conducted by the Philadelphia Water Department showed that for every dollar spent on green infrastructure, the city would receive $1.25 in return economic, environmental, and social benefits.  So far, measured water quality and stream hydrology are proving successful in Dover.

This type of example, project leaders hope, may serve as a model for the demonstration communities in Rhode Island, but work done by Save The Bay in wetlands throughout the state has already begun implementing some of these green infrastructure practices.

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Wenley Ferguson of Save The Bay examines marsh grass at a restoration site in Jamestown, R.I. Photo by Monica Allard Cox

Wenley Ferguson, director of habitat restoration for Save The Bay, described several such projects, including removing impervious surface and development of a small berm and planting dune grass at Barrington Beach to reduce stormwater runoff. Save The Bay also worked with Warwick on a project to remove deteriorated asphalt from roads that dead-end at the waterfront and, where possible, adding filter strips or infiltration techniques to reduce runoff.

While the projects described focused on reducing stormwater, several speakers spoke about the importance of investments in green infrastructure serving multiple uses, and in coastal communities, one of those uses is improving resilience. Adding plantings and reducing impervious cover, for example, can reduce an area’s vulnerability to flooding as well as reducing stormwater runoff.

Chaffee said that green infrastructure can have additional ancillary benefits, including preserving (or recreating) natural habitat and creating a more inviting landcape. It can also be more cost-effective than “gray” or hard infrastructure (stone or rock, for example).

Rubinoff said that the project is using pilot projects in the three communities to “understand obstacles and opportunities, demonstrate the process of site assessment, and design green infrastructure as a tool for coastal resilience.”

Project participants planned to visit sites in the communities where some green infrastructure elements have already been incorporated, and where other techniques might be applied.

The project is intended to identify green infrastructure techniques that will be most applicable in these developed coastal areas, but does not fund implementation of these tools. “This project only gets us to conceptual designs for these three places,” Rubinoff said, “We hope to identify funds for implementation.”

Other project partners include the Rhode Island Nursery and Landscape Association, the URI College of the Environment and Life Sciences, and Eastern Connecticut State University. The R.I. Coastal Resources Management Council, the R.I. Department of Environmental Management, and URI Cooperative Extension are serving in an advisory capacity.