Treating our rain with a garden
8 November 2007

Designing a garden to take advantage of Auckland's rain and help solve our stormwater problem makes sense to three final year Landscape Design students from Unitec.

The students, Kirsten Sach, Jamie Douglas and Zoe Carafice have designed a raingarden for the Ellerslie International Flower Show.

Zoe explains that a raingarden is just what it sounds like - a garden that soaks up rain water, mainly from your roof, but also your driveway and lawn.

"On a rainy day runoff from roofs, driveways and streets rushes into the stormwater systems carrying contaminants (e.g. zinc, copper and sediment) directly into our estuaries and harbours that can destroy important ecosystems and cause flooding. This problem is only going to increase as populations and cities grow," says Zoe.

The students want to raise public awareness and encourage people to take responsibility for their local environment by incorporating simple stormwater solutions into their own gardens.

Sustainable design can also be aesthetically beautiful, argues Kirsten.

"Our exhibit is a representation of a functioning raingarden in an intimate courtyard space off a master bedroom. It is an attractive, contemporary outdoor living space with three decks, a wall tank and lush, fresh green foliage that includes some critically endangered natives.

"We have chosen native plants as they are not used enough in residential gardens. A lot of native plants are well suited for a raingarden as they can tolerate wet and dry conditions. If we use more of them perhaps we can move some of them off the critically endangered list," says Kirsten.

Jamie is particularly impressed with the dual function of a raingarden.

"Specific soil material is used in a raingarden to reduce contaminants. A raingarden is also designed so water that pools in the planted areas is drained away within a 24 hour period. This means a raingarden can deal with both the contaminants and flooding issues of stormwater," explains Jamie.

Auckland Regional Council, Environment Management Chair, Dianne Glenn applauds the students initiative to showcase a solution to a serious environmental issue in the Auckland region.

"The Auckland Regional Council is proud to sponsor the raingarden. This is a brilliant opportunity to demonstrate how a residential raingarden can play a role in protecting our environment," says Cr Glenn.

Design Features
- The three areas of decking have been chosen for their permeability, helping to reduce runoff. Locally grown timber represents a low impact and attractive solution to hard surfaces within a garden.
- The central wall in the room represents a water tank. Wall tanks can incorporate water storage into a small garden, without compromising aesthetics. Water is collected off the roof and directed into the tank. When the tank is full the overflow becomes a water feature and pours into channels which direct water into the plants.
- The planting in the garden is a combination of native and exotic plans. The plants have been chosen for their lush, fresh green foliage and textures which represent rain and water, and compliment the clean lines and contemporary style of this garden.
- Endangered native plant species used in the design: Astelia grandis, Swamp astelia, Shiny sedge, Baumea complanata, and Leptinella tenella.

ENDS

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