By Phil Mercer
On the south-western coast of the world’s driest inhabited continent sits a green, vibrant city that is defying a chronic lack of rain and warming temperatures.
Perth is Australia’s driest major city, yet in its central areas at least, does not feel like a place that has confronted a water crisis. From its perch on Mount Eliza, Kings Park peers majestically over skyscrapers and office blocks, offering lush oases for weary workers and visitors, along with some of the most perfect grass your correspondent has ever seen.
The park with its grand avenues, memorials and statues has become a symbol of Perth’s resourcefulness in the face of monumental environmental challenges.
Between 1990 to 1999, the average annual rainfall in the Western Australian state capital was 766mm. Since 2009, that figure has fallen to 656mm.
“Western Australia has seen climate change happen faster and earlier than almost anywhere else on the planet. In the last 15 years the water from rain into our dams has dropped to one-sixth of what it used to be before that,” said Sue Murphy, chief executive of the Western Australia Water Corporation.
“We’ve pretty much lost the capital of Western Australia Perth’s water supply and so in the last 15 years we’ve had to rebuild that supply.”
For a city touched by the Indian Ocean, it has not had to look far for part of the solution. Two large water factories or desalination plants that turn the sea into potable supplies, have been built. Perth can now get half of its drinking water from the ocean, although conservationists worry that the process is expensive and energy hungry. There has been a hefty price for the community, with household bills doubling in recent years.
While stripping salt from seawater has helped to insulate a growing population against the effects of a drying climate, authorities have been experimenting with the Gnangara system, Perth’s largest source of groundwater.
A decade-long trial of injecting treated wastewater into deep aquifers up to 1,000m underground has recently ended. The recycled supplies have been flushed into sandy soil, which acts as a natural filtration process, before clean water is extracted for drinking and irrigation.
“The groundwater replenishment trial was highly successful and is now in production,” said Greg Claydon, the executive director of Science and Planning at the Department of Water.
“The project… is a highly innovative, sensible approach to the sustainable management of the use of the Gnangara groundwater resource. The green light to progress to seven billion litres a year last year is part of the state’s climate independence plan.”