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Raingardens
Raingardens are shallow depressions, typically planted with plants (preferably native), strategically located to collect, infiltrate and filter rain that falls on hard surfaces like roofs, driveways, alleys, or streets to minimise negative impacts of excessive runoff from these surfaces on lakes and streams.
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Raingarden (under construction) for treating road runoff at Verbena Road |
Raingardens are designed to take the place of your stormwater system and soak up and filter the water that comes off your roof and paved areas.
Other terms include mini-wetland, stormwater garden, water quality garden, stormwater marsh, backyard wetland, low swale, wetland biofilter, or bioretention pond. The variables include dimensions, design, engineering components, and plant selection.
Building a raingarden
The design of a raingarden can be varied to accommodate soils, watershed hydrology, existing drainage patterns, aesthetics, microclimate, and purpose.
Basic design components include:
- Grass filter strip
- A shallow surface-water ponding area
- A bioretention planting area
- A planting soil zone
- An underdrain system
- An overflow outlet structure.
There is no standard size for a raingarden. One formula provides that the bioretention area should be 5% to 7% of the drainage area that the raingarden is intended to accommodate. A raingarden should be placed near impervious surfaces so that rainwater will drain into the dip or depression. Locate the garden strategically near impervious surfaces, such as alleys, sidewalks, driveways, and under downspouts or gutters, to capture the rain as close as possible to the point where it falls.
Recent Research
- A home raingarden - what they do, how to build one, what not to do, exercise your imagination, FAQ's (added 18 December 2007)
- The Ellerslie Flower Show Gold Raingarden - a gold award design from the 2007 Ellerslie Show
- Raingarden photo gallery - photographs of raingardens
Recent Publications
Bracey S, Scott K, Simcock R. 2008.
Important lessons applying low-impact urban design: Talbot Park.
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In: Proceedings of NZWWA conference 15-16 May, Royal Lakeside Novotel, Rotorua 2008.
Trowsdale S, Simcock R. 2008.
Raingarden soils and efficiency.
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In: Proceedings of the NZWWA Conference, Rotorua, May, 2008.
Landcare Research. 2007.
Tamaki building raingarden poster 1.
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Landcare Research. 2007.
Tamaki building raingarden poster 2.
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Scott K. 2007.
Te Puru raingarden.
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Links
New Zealand
- Auckland City: growth and stormwater
- Waitakere City Council Development Services information leaflet on raingardens
- NZ Water Environment Research Foundation – On-site stormwater management guideline
- Landcare Research Tamaki building – stormwater management
- Geotech Systems Limited – Roof top raingardens
- Water: a household guide to improving water quality and managing water use in Hamilton
International
- How to construct a raingarden
Step-by-step illustrated guide at the LID Sustainable School Projects website. - Lady Bird Johnson Wildflower Center
This website provides a US Native Plant database that is searchable by US State. - Bioretention/Raingardens Discussion Group
This website provides a forum to exchange ideas, discuss issues and problems, and share any other information related to bioretention. - RainGardens.org
Basic information is provided on the design and use of raingardens. This site is a partnership stormwater education project between West Michigan Environmental Action Council (WMEAC) and the City of Grand Rapids Environmental Protective Services. - Friends of Bassett Creek, Minnesota
A comprehensive guide to the creation of raingardens for runoff management, habitat creation, and aesthetic value is provided with design and construction information and recommendations on plant material. - Stormwater Center
A comprehensive document entitled 'Stormwater Management Fact Sheet: Bioretention' provides detailed information on bioretention practices including applicability, design considerations and cost–benefit analysis. - Thornapple River Watershed Group
A basic introduction to the use of raingardens in rainfall management is provided, including a list of links to online resources for more information on creating a raingarden. - USEPA - Green infrastructure
Contacts
 | Robyn Simcock Email  |
Landcare Research | |
Phone: 09 574 4100 | |
| Details: Robyn Simcock |
