SW Australia Annual Rainfall Totals Down 16% Since 1970; Down About 30% Since 2000
When it comes to rainfall, south-west Western Australia has been hit by climate change harder than almost anywhere on earth, according to climatologist Pandora Hope from the Bureau of Meteorology. "South-west Western Australia was very much one of the first places to really see the shift that we expect with global warming, so it's had one of the biggest changes compared to many places in the world," she said.
Pandora Hope said there had been about a 16 per cent decline in the region's rainfall since 1970. "But if you look at the cool season — so winter through spring — the declines are in the order of 20 per cent," she said. "And if you actually look since about 2000, those declines intensify to about 30 per cent."
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The summer in Varley, a community four-and-a-half hours' drive east of Perth, is typically dry, but Ms Newman can't recall a time when it was looking quite so parched. "This is our third dry summer, and they incrementally build on each other," she said. "So at this point, now most of our dams are dry." Streamflow and runoff into dams are extremely sensitive to reductions in rainfall, according to the West Australian Department of Primary Industry, which predicts median streamflow to decline by nearly a quarter in the south-west by 2030. This comes on top of huge declines in runoff over the past 50 years.
"Since the 1970s, we've had a 20 per cent reduction in rainfall in this part of the state," said Tom Hatton, the former Chair of WA's Environmental Protection Agency. "Now, that doesn't sound like a lot, but it results in an 80 per cent reduction in streamflow. So, in the past (with) the catchments around Perth we could rely on something like 400 gigalitres of water a year to be replenished. "Now we're lucky if we get 70 gigalitres and we don't even rely on that."
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https://www.abc.net.au/news/2021-02-22/farmers-in-australias-southwest-adapting-to-less-water/13168666
