By Nicki Copley
Stormwater runoff & green infrastructure
When natural areas are developed into buildings and hard surfaces, rainfall can no longer soak into the ground as it might in a forest or field. Instead, rain hits impervious surfaces (roofs, concrete, asphalt etc.) and becomes stormwater runoff.
Traditional, or historic methods of stormwater management involve fast conveyance; runoff is transported rapidly through pipes into streams, rivers, and wetlands. And although these systems can be efficient, they are not resilient to large rainfall events where the volume of water entering the pipe and stream network can exceed a system’s designed capacity. When this occurs, pipe networks and waterbodies become overloaded, causing widespread flooding and erosion. Roads become rivers, and flooding can cause injury and death, as well as astronomical financial costs.
Stormwater runoff also has negative impacts on local biodiversity by transporting pollutants like oil, trash, bacteria, and nitrogen into local waterways, harming plant life and wildlife.
An alternative to traditional stormwater management is green infrastructure. Green infrastructure enables rainwater to soak or infiltrate into the ground close to where it fell and/or retains rainwater for reuse. Green Communities Canada states:
“Green infrastructure helps make urban areas work more like natural systems. When we develop cities, we replace natural vegetation and soils with hardened surfaces, like buildings, roads, and parking lots. This interrupts the natural functions the land used to provide—such as absorbing and purifying stormwater, filtering the air, providing habitat to animals and pollinators, regulating temperature, and more. Losing these natural functions makes our cities more vulnerable to the impacts of climate change, like flooding and extreme heat. It also makes our cities less sustainable, healthy, and joyous places to live.” – Green Communities Canada (n.d.) Living Cities Canada. https://greencommunitiescanada.org/programs/living-cities-canada/
Stormwater & landscape architecture
Landscape architects work with engineers, planners, ecologists, and other professionals to design and integrate a wide range of green infrastructure measures into their projects, including
- Bioswales
- Filter Strips
- Green roofs
- Detention areas
- Wetlands
- Ponds
- Infiltration planters
- Permeable paving
- Green roofs and walls
- Rain gardens
- Rainwater cisterns
They may also work to conserve or enhance existing natural features that can form part of an interconnected green infrastructure system, such as existing wetlands, forests, or meadows.
Most landscape architecture projects will consider stormwater to varying degrees. Many city governments require projects to meet certain ratios of permeable to impermeable surfaces and require developments to treat all stormwater runoff on-site. Landscape architects will collaborate with engineers to design stormwater solutions that meet stormwater management requirements whilst also positively contributing to biodiversity and aesthetic goals.
Online Resources:
There is a plethora of stormwater resources available online. Most local government agencies have some form of stormwater management guidance. In addition, many not-for-profit organizations also advocate for green infrastructure and have helpful resources available. The list below is by no means comprehensive but contains several resource links that stand out as being particularly thorough.
Please note: reference to any organization is not to be construed as an endorsement or recommendation of any information, goods or services supplied by that organization.
Organization: United States Environmental Protection Agency (EPS)
What? Contains a concise definition of green infrastructure and lists components that together form a network of green infrastructure, such as rain gardens, bioswales, permeable paving etc. Under each green infrastructure component, there are links to different programs around the US.
Also contains links to the United States Environmental Protection Agency (EPS) Stormwater Best Management Practice Fact Sheets, which cover aspects like design considerations, cost implications, limitations, and maintenance i.e. a typical maintenance schedule for a grassed swale.
Why visit? Find detailed information on how to incorporate green infrastructure measures into projects or assignments. The EPS fact sheets, in particular, contain useful information about the benefits and maintenance of the systems. The links to the different programs around the US will be less applicable to some, but still contain helpful generalized material (descriptions, diagrams, sections, case study photos etc.).
Organization: American Society of Landscape Architects (ASLA)
What? The landing page offers a brief description of green infrastructure and lists numerous relevant organizations, resources, and research articles. The sub-categories i.e. Constructed Wetlands, Wildlife Habitat & Corridors, provide links to additional resources.
Why visit? These pages act as a library of resources around this topic. Useful if you are looking to find or browse for organizations and articles relevant to green infrastructure.
Organization: Green Infrastructure Ontario Coalition
What? “Green Infrastructure Ontario (GIO) Coalition is an alliance of organizations that share a common vision for a healthy, green Ontario where the economic, social, environmental and health benefits of green infrastructure are fully realized.” Their resources page contains links to many resources including reports, guides, and videos.
Why visit? While many green infrastructure resources focus primarily on the stormwater management function of green infrastructure, this site has simple but clear descriptions of the additional benefits of green infrastructure components i.e. public health, economics, ecosystem health. The guide “A Green Infrastructure Guide for Small Cities, Towns and Rural Communities”, (a partnership between Green infrastructure Ontario Coalition and Green Belt) breaks down the benefits of each green infrastructure component and indicates what type of landscape they are suited to, with easy-to-follow case studies with before and after images of how green infrastructure could be implemented.
Organization: State of Victoria, through the VAS Partnership, the Inner Melbourne Action Plan and the University of Melbourne
What? A comprehensive guide on green roofs, green walls, and green facades. The guide covers aspects like site analysis (climate, weight loading, drainage, access, etc.), design and planning, and considerations for installation (waterproofing, protection layers, drainage, vegetation, soils, etc.). It also has a section on evidence-based benefits of green roofs, walls, and facades that cover a range of benefits, including energy reduction in buildings, urban cooling, stormwater management, and human health.
Why visit? Although the guide is targeted at projects based in Melbourne and Victoria, Australia, the guide contains significant material relevant to anyone looking at designing green roofs, walls, or facades. A worthwhile read, to help understand the complexities of these systems and their design opportunities and constraints.
Organization: Green Communities Canada
What? Depave Paradise is a project of Green Communities Canada and local partners in communities across Canada. They support volunteers to remove unwanted pavement and plant native gardens. Their learning resources page has great info on understanding stormwater management and the benefits of green infrastructure compared to traditional management i.e. gutters, and pipes. They also have links to two free online courses.
Why visit? Learn about a community-driven effort to improve the built environment. Use their resource page and courses to gain a general understanding of stormwater management.
