New Zealand Rain Garden Information Guide

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Post on 24-Jan-2015




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Rain Garden Information Guide


  • 1. rain gardens1 In the natural environment, a storm is a fairly Rain Rain,common occurrence. Part of the rainfall isintercepted by trees and vegetation, while the rest is absorbed into the earth. rivers and streams become swollen to accommodate come and stay excess rainfall. They continue to flow over a number of days, slowly filtering and removing sediments before water reaches the sea and our precious beaches.How is it then that our beaches and harbours are becoming increasingly polluted and When will we acknowledge that stormwater is precious eco systems irreparably damaged? Why are we experiencing so many issues with not the result of storms? flooding and landslides in our landscape? Words & Photos: Kirsten sach so often we see results of flooding in our cities, communities and in our own backyards. i often hear people talk of a particularly bad20 NEW zEalaNd Backyard & gardEN dEsigN idEas

2. rain gardens2 NEW zEalaNd Backyard & gardEN dEsigN idEas 21 3. rain gardens 3storm that has caused such terrible damage, asconsider how rainfall will affect our landscapeif its the fault of the storm. or at the very least, how can we imitate whatstormwater is the result of run-off from hard nature does so expertly.surfaces like concrete driveways, roof areas and Presently in a rainstorm, water rushes intoroads. We often think of rain as cleansing butdrains at such acceleration that all manneras it hits roofs and other impermeable surfaces,of pollutants, such as heavy metals, find theirit becomes a medium for a whole range ofway into our waterways and straight into thenasty pollutants that end up in our oceans. sea. Our main stormwater drains are nowThe more we divide up our land and coverstraining under the pressure of coping with theit with hard surfaces, the more likely it is that sheer volume of stormwater, so much so thatflooding will result. This problem is only going to local councils have been working extensivelyget worse as populations increase and cities grow.on ways to alleviate the pressure on our drainsin New zealand we are proud of ourby implementing different ways to treat run-offsupposedly clean green image and our stunning within our urban environment.beaches, but we have an underlying problem One such solution that offers a way to treatthat is often ignored or just not considered when stormwater in a residential garden is the creationwe build our houses or develop our gardens. of a rain garden. it is a way of collecting rain offThe question we need to ask ourselves is what your roof or driveway and directing it into specifichappens to rain when there are no trees togarden areas, where soil and plants absorbintercept some of the fall, when we concretethe rain, filtering, removing sediments andour driveways, subdivide our land and build yet contaminants before the relatively clean wateranother home resulting in yet more and more is then released back into the main stormwater 4impermeable surfaces.if we are going to cut down our forestsand develop our land then surely we need tosystem. By treating stormwater in this way it notonly helps to purify, but also slow down theoverall flow rushing into the sea.22 NEW zEalaNd Backyard & gardEN dEsigN idEas 4. rain gardens5a rain garden at its simplest is an area ofand beaches, it also creates an opportunityKirsten Sach Landscape Design is an award-garden that has sub drainage with a specialisedto showcase a specialised planting scheme. winning landscape design company. Leadsoil media designed to treat stormwater run-offBuildings need to become water collectors like designer, Kirsten Sach, won Gold for her Rainand is densely planted to maximise absorption. our forests, and when the water cycle is fully Garden design at the 2007 Ellerslie Internationalit is not expensive to build and costs only slightly integrated into the designs of our gardens and Flower Show, and Silver for her Kia ora ai temore due to drainage pipe and soil volume. buildings, only then can we say that rain haswai (Make the Water Well) at the 2008 EllerslieThe size of a rain garden is based on thebeen treated as nature intended. n Flower Show. of roof area or total run-off.a rain garden is a simple and economicalway to create an attractive means of1 & 2. This award-winning garden was3,4 & 5. This garden demonstratestreating stormwater in your own backyarddesigned for the Ellerslie International Flower storm water planter boxes and is anotherand helps protect the future of our streams Show and sponsored by Auckland Regional Auckland Regional Council-sponsoredand beaches. Plants that are used mostCouncil. It shows how rain can be collected off garden for the Auckland Flower Show. Thissuccessfully in a rain garden are often those a roof into a central water tank wall that hasexample shows how rain can be collectedfound on the edges of waterways such as been incorporated into the garden as a meansvia a disconnected downpipe and stored instreams or estuaries. They are plants that areof creating garden rooms for privacy, and toa pond. Once the pond is full, it overflowsused to being inundated by water for shortconserve water for use in the garden in prolonged into a series of raised rain gardens thatperiods and drying out for an extended length dry periods. The water tank has an overflow atpurify the water before it re-enters theof time. Plants such as reeds, restios, tussock,the front and when it is raining and the tank main storm water system at the bottom.cabbage trees and flaxes are all well suitedis full, the overflow becomes a water feature,The pond accommodates goldfish, whichto such conditions and there are many morewith excess water feeding into rain garden areas. help keep mosquitoes at bay. The pond alsospecies that are suitable for rain gardens. Water never ponds for longer than 24 hoursforms a feature of the garden and acts ascreating these simple solutions within awithin the garden and is designed to stay at aboth an aesthetically pleasing element oflandscape design is not only a sustainableminimum depth so there are never any problems the design and a means of helping conserveway to minimise the effects on our waterwayswith mosquitoes.and purify water. NEW zEalaNd Backyard & gardEN dEsigN idEas 23