Green Infrastructure

Green roof installed at WVU's Brooks Hall


A new report by the Center for Neighborhood Technology and American Rivers quantifies the economic value of green infrastructure. This tool is meant to help municipalities adopt cost-effective stormwater management techniques. The Value of Green Infrastructure: A Guide to Recognizing Its Economic, Social and Environmental Benefits uses current research on green infrastructure performance and provides methods for calculating related benefits in water management, energy, air quality, climate change and community livability. The guide is meant to fill an information gap that inhibits use of green infrastructure.


What Is Green Infrastructure and Why Does It Matter?

Green infrastructure (GI) is a network of decentralized stormwater management practices, such as green roofs, trees, rain gardens and permeable pavement, that can capture and infiltrate rain where it falls, thus reducing stormwater runoff and improving the health of surrounding waterways. While there are different scales of green infrastructure, such as large swaths of land set aside for preservation, this guide focuses on GI's benefits within the urban context.

The ability of these practices to deliver multiple ecological, economic and social benefits or services has made green infrastructure an increasingly popular strategy in recent years. In addition to reducing polluted stormwater runoff, GI practices can also positively impact energy consumption, air quality, carbon reduction and sequestration, property prices, recreation and other elements of community health and vitality that have monetary or other social value. Moreover, green infrastructure practices provide flexibility to communities faced with the need to adapt infrastructure to a changing climate.

Green Infrastructure Benefits and Practices

Rain Gardens

Bioretention and infiltration practices come in a variety of types and scales, including rain gardens, bioswales and wetlands. Rain gardens are dug at the bottom of a slope in order to collect water from a roof downspout or adjacent impervious surface. They perform best if planted with long-rooted plants like native grasses. Bioswales are typically installed within or next to paved areas like parking lots or along roads and sidewalks. They allow water to pool for a period of time and then drain, and are designed to allow for overflow into the sewer system. Bioswales effectively trap silt and other pollutants that are normally carried in the runoff from impermeable surfaces. While the multitude of benefits provided by wetlands has been well documented elsewhere, this guide only addresses smaller scale practices.

Learn More About Rain Gardens

Green Roofs

A green roof is a rooftop that is partially or completely covered with a growing medium and vegetation planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems. Green roofs are separated into several categories based on the depth of their growing media. Extensive green roofs have a growing media depth of two to six inches. Intensive green roofs feature growing media depth greater than six inches (GRHC).

Learn More About Green Roofs

Permeable Pavement

Permeable pavement allows for the absorption and infiltration of rainwater and snow melt onsite. There are several different names that refer to types of permeable pavement, including pervious or porous concrete, porous asphalt and interlocking permeable pavers.

Learn More About Permeable Pavement

Water Harvesting

Water harvesting is defined as the redirection and productive use of rainwater by capturing and storing it onsite for irrigation, toilet flushing and other potential uses. Water harvesting treats rainwater as a resource rather than as a waste stream. There are two main water harvesting practices: downspout disconnection and the use of rain barrels or cisterns.

Downspout disconnection is the process of directing roof runoff away from sewer systems and onto local property for irrigation purposes. Using rain barrels or cisterns captures rainwater, diverting it directly into these storage containers. The stored water can be used onsite for multiple purposes such as flushing toilets and irrigation. The practice of water harvesting requires that catchment areas be sized according to projected water-use needs in order to maximize the benefits of this practice.

Learn More About Rain Barrel and Stormwater Education

Tree Planting

Planting trees provides many services which have ecological, economic and social implications. Whether measured on a treeby-tree basis or on a larger scale such as an urban forest, tree planting has a multitude of benefits. ​