During the 1970s, something strange happened to the weather around Perth. It became much drier.

Until then, Perth dams had received average annual inflows of 338 gigalitres per year. From 1975 to 2000, inflows dropped to 177 gigalitres. Since then they have fallen further, to under 100 gigalitres.

Last year, Perth’s dams received their lowest inflow in more than 100 years. Run-off into the dams had been ‘virtually non-existent’ since the start of winter, Water Corporation spokesperson Clare Lugar told Perth Now.

This long-term decline is due, at least in part, to climate change. Until the 1970s, rain-bearing fronts swept across south-western Western Australia from the Southern Ocean from autumn to spring. Over the past 40 years, the changing climate has pushed these fronts southward. The rain now falls over the ocean rather than over the land.

We know about the causes of the long-term drying trend thanks to research undertaken by CSIRO and the Bureau of Meteorology with support from the Government of Western Australia. Prompted by the need to investigate the winter rainfall decline, the Indian Ocean Climate Initiative (IOCI) commenced in 1998. IOCI has influenced public policy by providing high-quality, respected science information.

The research has influenced crucial decisions to secure alternative water sources for Perth in response to the drying trend, hastening and strengthening the case for a Perth desalination plant. IOCI research also informed the 2011 decision by the WA government to expand a second desalination plant to meet the urgent need for a new water source.

Today, in addition to the ones in Perth, there are desalination plants in South Australia, Victoria, New South Wales and Queensland.

The Western Australian experience highlights the need for Australian urban water policy to include a range of climate change adaptation measures. These include considering a variety of water sources; using fit-for-purpose water for appropriately planned and designed infrastructure and property developments; protecting ecosystems and biodiversity; encouraging demand reduction and lower levels of outdoor use; and informing the public and training the work force.

Does your organisation have in place water saving measures?
What has happened to your region’s rainfall in recent years?