Beyond Stormwater

By Steven Whitman, EdD, AICP, and Brian Eisenhauer, PhD

What do you picture when you hear "green infrastructure"?

For most planners, the term conjures up images of rain gardens, bioswales, green roofs, and other isolated design solutions focused on mitigating the impacts of stormwater. What a lot of people don't realize is those approaches represent only a fraction of the potential that green infrastructure offers as a strategy for community planning and design.

By using green infrastructure solely as a stormwater management technique, urban planning and design professionals are missing an opportunity to leverage the practice more broadly as a truly living and interconnected infrastructure that provides a wide range of benefits, including habitat for increased biodiversity, improved air quality, temperature regulation, space for recreation, nature therapy, and more. This is particularly important given many of the challenges of today around a changing climate, food insecurity, and equitable access to open space and natural areas. Some of our most urban and economically disadvantaged areas exhibit the greatest need. Fortunately, potential exists for communities to leverage shared infrastructure more effectively to address needs more equitably.

But before we can capitalize on these opportunities, we first need to redefine and broaden the concept of green infrastructure and acknowledge that it is most effective when embraced and used as an integrated comprehensive approach.

The rooftop farm on the power plant of Boston Medical Center supplies herbs, leafy vegetables, and fruits to the hospital's staff and patients while providing insulation and slowing stormwater runoff. Photo ©Michael Piazza, Saint Lucy Represents.

Evolution of green infrastructure

The term "green infrastructure" was once used to represent natural resource-focused conservation strategies associated with such famous examples as New York's Central Park and Boston's Emerald Necklace. Over time, examples of green infrastructure have included regional and national ecological networks and smaller municipal green space networks such as village greens, waterfront parks, and conservation lands.

However, efforts to implement green infrastructure solutions eventually narrowed to focus primarily on site-specific design solutions such as rain gardens and green roofs, and stormwater management became the dominant understanding and application of green infrastructure.

We found this narrower interpretation to be common when we recently examined the green infrastructure planning work of more than 50 municipalities from across the U.S.

The purpose of our 2018 study — Community Resilience: An Investigation of Municipal Green Infrastructure Planning and the Role of Ecosystem Services — was to understand how municipalities define green infrastructure, what benefits they are seeking as they plan for green infrastructure, and how land-use regulations play a role in implementing green infrastructure initiatives.

This initial "rebranding" of green infrastructure as a water-centric set of design solutions happened for several good reasons, including the availability of funding for and the importance of stormwater issues, and it certainly helped further our understanding of the importance of functioning natural systems within the built environment. Environmental agencies and organizations influencing the more stormwater-focused interpretation saw the potential to address significant water quality challenges using the concept, and they have produced good results.

However, this narrow definition acknowledges only a fraction of what green infrastructure can be used to accomplish.

A Transect of Green Infrastructure Systems and Solutions

This cross section shows a range of green infrastructure examples from an urban area out to a more undeveloped setting. Ideally these would be interconnected systems that create a green infrastructure network throughout the community.

Illustration by Elizabeth Kelly, Resilience Planning & Design, for City of Portsmouth, New Hampshire.

An ecosystems approach

Human populations are not separate from the environment upon which we depend.

The ecosystems of which we are a part are well defined as coupled human-natural systems, communities of interrelationships that people influence and depend upon. Returning to the roots of green infrastructure planning reminds us to consider this interconnected nature of ecosystems and their inherent resilience.

Conceptualizing green infrastructure as a comprehensive approach to designing the built environment that promotes — not just conserves — ecosystem services in an equitable manner can promote many benefits for our communities.

The goal of this approach can be visualized as a network of green infrastructure areas of varying sizes and solutions across a municipality or region. Such a network would include large intact natural areas, natural resource corridors that may double as recreation or transportation infrastructure, and smaller site-level solutions within the built environment. We visualize these networks of natural lands and constructed ecologies and embedded solutions as the connective tissue, heart, lungs, and digestive system of a community.

Like the human biological system, no community is complete without such a critical network of healthy living infrastructure.

Most communities in the U.S. have severed their natural resource networks through the construction of roadways and decades of development activity. What were once dynamic, interconnected natural systems are now reduced to patches of degraded open space, if they exist at all. An ecosystems approach to green infrastructure, on the other hand, provides a means for ecological processes to be incorporated into the built environment, rather than destroyed by it.

Mound Bayou, Mississippi, launched an ecosystems approach in 2010. Their green infrastructure plan for the downtown includes a reimagined park corridor and improved municipal properties complete with trees for shade, improved air and water quality, and food production. The plan also considers these interconnected parcels for alternative transportation modes and outdoor education, recreation, and entertainment. While rain gardens and other common green infrastructure techniques are used, they are a small part of an intricate, integrated landscape-scale approach to address many known issues in the downtown.

Planning that embraces the ecosystem approach to green infrastructure provides a way to incorporate the important roles natural resource systems play in community well-being and for meeting critical needs, while also looking for areas that would benefit from renewal through the restoration of natural systems and their functions.

Broader benefits

Restoring valuable ecosystem functions to our built environments requires using a variety of interconnected green infrastructure strategies. We can no longer install isolated rain gardens. We need to plan and design with inspiration from nearby forests, wetlands, and meadows, which are complex and part of larger natural landscapes.

We must also consider multiple ecosystem functions in our work. Doing so will provide increased benefits, including access to open spaces and nature for all residents, habitat for pollinators, and heat island impact mitigation, as well as address many other needs to enhance a community's adaptation efforts and overall resilience.

These benefits are called "ecosystem services," according to the Millennium Ecosystem Assessment published by the United Nations, and include "provisioning services such as food, water, timber, and fiber; regulating services that affect climate, floods, disease, wastes, and water quality; cultural services that provide recreational, aesthetic, and spiritual benefits; and supporting services such as soil formation, photosynthesis, and nutrient cycling."

In the plans we examined in our 2018 study, it was no surprise to see that, of the potential benefits of green infrastructure, water-related benefits were the most commonly cited. However, we also found that, on average, each plan — regardless of which definition of "green infrastructure" it used — identified 14 distinct ecosystem services that would result from proposed strategies, including air quality improvements, recreation opportunities, aesthetic improvements, and health and wellness. But, when we looked at specific applications, it is clear that municipalities' focus shifts strongly to water once green infrastructure is developed beyond the conceptual stage.

Municipalities face complex financial, equity, and resilience-related issues that require holistic solutions. If green infrastructure initiatives are recognized by local officials and stakeholders as effective comprehensive solutions to address health and wellness issues, to avoid costs of replacing natural processes with man-made interventions, to provide economic development opportunities, and to promote resilience goals, they have the potential to generate more interest and support from diverse constituents. This will help leverage access to additional funding sources, support, and future stewards for this critical living infrastructure.

Each additional benefit adds value and broadens stakeholder interest in the green infrastructure initiatives being identified. With increasing environmental concerns and dwindling municipal budgets, green infrastructure can offer the holistic solutions we need to make our towns and cities more resilient.

Where we go from here

One of the biggest takeaways from our study — and one of the biggest barriers to implementing a systems approach — is the fact that, in many plans we reviewed, even the most comprehensive approaches to green infrastructure lacked sufficient regulatory pathways to implement holistic solutions. Indeed, municipalities with the most comprehensive understanding still tended to address distinct issues in silos when it came time to create new land-use regulations, and these regulations were largely one dimensional.

What we need are new regulatory models that will complement the nonregulatory green infrastructure initiatives already underway. These are needed for our urban centers, suburbs, and on previously undeveloped lands. It is time to envision how our land-use regulations can protect and restore an interconnected web of green infrastructure in each of our communities. This type of regulatory model does not currently exist, but it is needed.

Planners have an opportunity to collaborate on the creation of a new green infrastructure regulatory system that improves the design of coupled human natural systems by ensuring that the built environment promotes the health of ecosystem services and equitable access to them.

In the meantime, we encourage planners to reflect on their understanding of green infrastructure to apply and embrace the concept more broadly in our communities.

Steven Whitman is a professional planner, part-time faculty member at Plymouth State University in New Hampshire, and the founder of Resilience Planning & Design LLC. Brian Eisenhauer is the director of the Office of Environmental Sustainability and a professor at Plymouth State University.

6 Green Infrastructure Planning and Design Principles

Intersecting systems meet community goals and provide positive returns on investment.

In APA's PAS report Green Infrastructure: A Landscape Approach, authors David C. Rouse, FAICP, and Ignacio F. Bunster-Ossa offer six principles for planning and designing green infrastructure systems that provide multiple benefits for people and their environments.

Water Table/Water Glass, a sculpture by Buster Simpson at a condominium complex in Seattle, uses its two elements to create utilitarian fountains to nurture wetlands with rainwater from the buildings' roof. Photo courtesy Buster Simpson.

1. MULTIFUNCTIONALITY

The different systems that intersect in green infrastructure — hydrology, transportation, energy, economy, and so on — provide multiple, overlapping functions that can, and should, be leveraged to achieve seemingly disparate community goals such as flood control, reduced dependence on imported energy, and improved public health outcomes.

2. CONNECTIVITY

Green infrastructure is most effective in providing services and benefits when it is part of a physically connected system across the landscape (e.g., a natural reserve or a park). To achieve this at the landscape scale, planners and designers should establish physical and functional linkages across urban, suburban, and rural landscapes and across scales to connect the site, neighborhood, city, and region.

3. HABITABILITY

The habitability principle positions green infrastructure as visible space that provides outdoor habitat for people, flora, and fauna. The mission of the public health profession — to foster conditions in which people can be healthy — is central to this idea. Example outcomes include improved air and water quality, increased opportunity for outdoor recreation and exercise, and restoration of native habitats.

4. RESILIENCY

Green infrastructure can increase community resiliency over short and long time frames: Trees and green roofs can counteract the urban heat island effect; maintaining the natural flood absorption capacity of coastal or riparian wetlands and floodplain areas can reduce vulnerability to storms and reduce damage to protective gray infrastructure; and techniques that absorb rainfall on-site can reduce the impacts of urban runoff during storm events.

5. IDENTITY

Green infrastructure can contribute to the visual definition of a place that is desirable to live in or visit. A tree, for example, can act as a carbon sink and source of shade. But thought should also be given to the type of tree, its location, any added recreational or spiritual benefit it might provide, and the aesthetic or culturally significant effects it might have. In this context, the integration of art within the public sphere becomes a relevant consideration.

6. RETURN ON INVESTMENT

In a time of scarce financial resources, planners and designers should use cost-benefit analyses to demonstrate how green infrastructure can reduce costs and yield positive financial outcomes for governments, institutions, businesses, and citizens; to plan and design green infrastructure components to achieve goals such as reduced energy use and increased revenue; and to establish targets and indicators to monitor whether these goals are being met in implementation.

Case Study: Portsmouth, New Hampshire

An open space plan takes a comprehensive approach to green infrastructure.

In 2019, Portsmouth, New Hampshire, completed an open space plan that embraced a comprehensive approach to green infrastructure.

Map by Elizabeth Kelly, Resilience Planning & Design, for City of Portsmouth, New Hampshire.

Building a Resilient Future: An Open Space Plan presents a vision of Portsmouth's green infrastructure network that includes large, unfragmented conservation lands and other natural areas containing critical wetlands, forests, and agricultural soils that provide important ecosystem services to the community, while helping to "create, enhance, and connect open space corridors throughout Portsmouth," notes Peter Stith, AICP, the city's principal planner.

The plan, adopted in February 2020, has seen great support from the city, say Peter Britz, Portsmouth's environmental planner and sustainability coordinator. He points out a number of the plan's services, including "enhancement of biodiversity, climate change resilience, and water quality improvements while providing better public access and connectivity."

Expanded land conservation efforts and green street initiatives will restore green corridors across the city, and the vision also calls for site-level improvements in parks and playgrounds.

It also advocates for updated land-use regulations that will require developers to provide community green space in their site designs, resulting in new developments that integrate multiple functions, such as gathering areas, shade, food production, stormwater management, and habitat.

Stith notes that funding for two projects has been requested, and that annual review of the plan could result in further capital improvement plan funding.

The city will also collaborate with regional land conservation groups to acquire additional land or easements "as we work on revising our land-use regulations to accomplish the goals of the plan," he says.