Green stormwater infrastructure (GSI) describes stormwater practices that use natural systems (or engineered systems that mimic or use natural processes) to capture, clean, and infiltrate stormwater; shade and cool surfaces and buildings; reduce flooding, create wildlife habitat; and provide other services that improve environmental quality and communities’ quality of life. Examples include green roofs, bioretention, tree trenches, and vegetated swales (Tucson). GSI is one component of green infrastructure, which refers to ecological systems, both natural and engineered, that act as living infrastructure. Green Infrastructure elements are planned and managed primarily for stormwater control, but also exhibit social, economic and environmental benefits (Syracuse University).
The United States Environmental Protection Agency (US EPA) describes sustainable stormwater management as focusing on reducing runoff and improving water quality. Often also called low impact development (LID), sustainable stormwater management includes a variety of practices that help maintain natural hydrologic cycles through site grading, vegetation, soils and natural processes that absorb and filter stormwater onsite, while also minimizing erosion, flooding and water pollution (US EPA).
Sustainable stormwater management is one component of environmental sustainability. Broadly, environmental sustainability is managing natural resources and protecting global ecosystems to support health and wellbeing, now and in the future ().
For a discussion of the role of GSI in sustainability and ecosystem services, see Multiple benefits of green infrastructure and role of green infrastructure in sustainability and ecosystem services.
Green stormwater infrastructure can be implemented at the site, neighborhood, watershed, and city scales. Strategies vary with local factors, such as soils, hydrology, regulations, and social factors (e.g. acceptance, environmental justice, etc.). Infiltration or other methods of retaining water on-site are typically preferred, but may not be feasible due to constraints. As the implementation area increases, it often becomes easier to accommodate stormwater retention since there are more potential locations where retention is feasible. Examples of how implementation varies with scale are provided below.
For case studies of GSI implementation and planning, visit the following pages.
Several cities, watersheds, and regions have developed sustainable stormwater or green infrastructure plans. Some examples are provided below.
For information on GSI practices, click here.