A major CSIRO report has projected a marked decrease in river flows and water yields in south-west Western Australia by 2030 under the impacts of climate change and increasing demand.

The CSIRO South-West Western Australia Sustainable Yields Project, undertaken in partnership with the WA Government, estimates changes to future water yields having regard to both climate change and future development. 

The Minister for Climate Change, Energy Efficiency and Water, Senator Penny Wong, today welcomed the release of the report for which the Australian Government provided $5.2 million under its Water for the Future initiative.

“We know that the Perth region has already experienced a reduction in surface water runoff of around 50 per cent since the mid 1970’s; a change that shows trends and patterns that are consistent with human-induced climate change,” Senator Wong said.

“The report highlights the likelihood of a further reduction in Perth’s water supplies by 2030, which is of considerable concern.”

The key findings from the study, which covers almost 40,000 square kilometres between Geraldton and Albany, found that:

• South-west WA will face a one-quarter reduction in water availability by 2030, relative to the last 30 years;
• Under the best-case scenario, mean annual surface water yields will decrease by 4 per cent by 2030; and
• Under the worst-case scenario, that reduction will be 49 per cent by 2030.

“Climate change demands that we plan for a future with less water. This report is crucial for WA, as it will inform key water planning and management decisions for Perth and the entire south-west of the state,” Senator Wong said.

Other findings from the study have found that ground water availability is projected to decline. Under an extreme dry future, water yields in three important groundwater areas – including the Gnangara aquifer which supplies tap water to Perth – could decline by over one-third by 2030.

Groundwater-dependent ecosystems, such as wetlands and vegetation communities that depend on groundwater levels that are close to the soil surface are also expected to experience additional stress by 2030.

The study is one of three recently completed sustainable yields projects that build on the successful Murray-Darling Basin Sustainable Yields project. 

“The Australian Government is working with all states and territories to prepare for the effects of climate change, including reduced water availability,” Senator Wong said.

“Based on the best available scientific information, these sustainable yield projects will help build a consistent analytical framework for water policy decisions across the nation.” 

The CSIRO South-West Western Australia Sustainable Yields Project reports can be found at: www.csiro.au/partnerships/SWSY.html

Public briefings on the impact of the findings on the south west will be conducted in Bunbury on 4 March and the impact on irrigation water supplies in Perth on 5 March. For more information about these briefings, contact Anne McKenzie on 08 9333 6221 or 0447 848 568