Horticulturist Tim Edmondson designs underground river system for Coombs Block | Canberra time

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An underground river system meandering beneath a garden in Coombs allows a family to capture the large amounts of water typically wasted in storm drains. In a suburb not well known for its green canopy, the Dickersons developed a climate-friendly oasis in just a few years, thanks to the installation of a block water harvesting system. Using the expertise of horticulturalist Tim Edmondson, runoff water moves through trenches into an underground system lined with geotextiles, river rocks and sand, mimicking a natural river bed. Mr Edmondson said the garden harvests almost all the water that falls on the property, compared to the 70 per cent a typical Canberra block would lose. “The whole thing is 400 millimeters below the trim level, and then there’s another 300 to 400 millimeters deep, so tree roots can get in,” he said. “During the hottest part of the day, when they need water the most, they can access moisture for transpiration and continue to grow.” He said the system helps control plants by limiting growth factors: temperature, light and humidity. “As we move from low temperatures in winter to summer when the temperature rises, the availability of moisture in the soil for plant growth suddenly decreases,” Edmondson said. “So you have this huge period in the summer with good light, good temperature but no water. By making water readily available, you push potential growth up rather than down in the lower third. ” approached Mr. Edmondson after seeing the success of the water harvesting system he built at Orana Steiner School, following the 2004 bushfires. Mr. Edmondson received the Horticulturist Award of the Year from the Australian Institute of Horticulture in 2010 for the project, with students planting trees that now He said that 10 years after planting, the trees in the zoned harvesting system area were about one meter tall in diameter, while the drip-watered trees were still small enough to reach his hands. Mr Edmondson said that while there were some critical points in the design of a home harvesting system like the Dickersons, it was not out of reach for some. someone with some expertise in soil hydrology. “You want to be specific, but it’s not that complex,” he said. According to the Coombs case study, the benefit of the system is not just the rapid growth of the garden, but the natural cooling provided by the thick foliage. With new suburbs sprouting up the Mologolo Valley and fake lawns being rolled out with increased frequency, Edmondson said new suburbs risk becoming heat traps. READ MORE: Coombs owner Luke Dickerson says the chilling effect of their now six-metre trees was significant. “We can certainly enjoy our terrace under the shade of the tree in the late afternoon, when in the past we would have been roasted alive,” he said. After incorporating passive solar principles into the house, including double-glazed windows and facing north-facing main windows, Mr Dickerson said the interior temperature was also regulated. With around 8,000 more people in Canberra each year, Mr Edmondson said learning from nature about power generation solutions was essential. “The more we can emulate that, the better life we ​​will have,” he said. Our reporters work hard to provide local, up-to-date news to the community. Here’s how you can continue to access our trusted content:



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