Groundwater in Perth supplies nearly 40 per cent of Perth’s scheme water. The deep Leederville and Yarragadee aquifers supply most of that 40 per cent. Groundwater also supports many wetlands and lakes, as well as urban development and horticulture, and is the reason we have green ovals and parks for sports and recreation.
The $7 million Perth Region Confined Aquifer Capacity (PRCAC) study was a four-year project that improved our understanding of:
- how the Leederville, Yarragadee and Superficial aquifers interact
- where the recharge zones exist in the deeper aquifers
- how groundwater abstraction and injection of recycled water impact groundwater levels.
PRCAC investigated the capacity for continued groundwater abstraction from the deep Leederville and Yarragadee aquifers. It also considered how and where managed aquifer recharge would be most effective to support groundwater use into the future.
We used this study to:
- decide, with the Water Corporation, on the best injection and abstraction locations for Stage 2 of the Beenyup Groundwater Replenishment Scheme
- develop long-term management strategies on groundwater abstraction from the Leederville and Yarragadee aquifers.
What we did during the PRCAC study
We partnered with leading research institutions and the Water Corporation to conduct this study from 2012 to 2016. We have built on the work since then by investing in science to understand the aquifer systems below greater Perth.
Through this study we:
- constructed seven deep aquifer monitoring bores to a maximum depth of around 900 metres
- collected information from monitoring bores to understand groundwater age, flow directions and connectivity across faults
- completed seismic surveys to determine the location of faults that could impact groundwater flow
- flew an airborne electromagnetic (AEM) survey to identify faults and where aquifers may be connected
- refined the Perth Regional Aquifer Modelling System (PRAMS)
- assessed seawater interface movement in the offshore Leederville and Yarragadee aquifers with Flinders University.
Key findings and how we are using the information
Key findings from this investigation include:
- The abstraction volume from the Leederville and Yarragadee aquifers is constrained mainly by connection to the Superficial aquifer, where watertable drawdown potentially impacts groundwater-dependent ecosystems.
- There is generally a low risk of seawater intrusion in the deep aquifers.
- The risk of subsidence from deep aquifer abstraction is minor.
- Choosing optimal locations for aquifer injection (also known as replenishment) can:
- bolster deep aquifer pressures
- reduce leakage from the Superficial aquifer
- help recover groundwater levels at high-value groundwater-dependent ecosystems and in other important areas
- allow for full recovery of injected water while maximising the use of the deep aquifers for scheme supply.
- There is potential for additional water to be abstracted from the Leederville aquifer west of the Badaminna fault (north of Yanchep). However, further work is needed to quantify sustainable allocation limits and the potential impacts of abstraction.
Where to get more details
You can ask for copies of the internal technical reports for this investigation by emailing groundwater.info@dwer.wa.gov.au. These include:
- Perth Region Confined Aquifer Capacity study – Aquifer assessment: review and scoping report, HR351 (Clohessy 2015)
- Bore completion report, Perth Region Confined Aquifer Capacity study, HR364 (Rothery 2016)
- Perth region Leederville and Yarragadee aquifer reinterpretation report, HR363 (Maidment & Rothery 2016)
- Assessment of PRAMS modelling completed for the Perth Region Confined Aquifer Capacity Study, HR365 (Karelse 2016)
- Assessment of the potential for saline intrusion into the Perth Region Leederville and Yarragadee aquifers, HR366 (Patterson 2016)
- Perth Regional Confined Aquifer Capacity study: Method for assessing impacts at groundwater-dependent ecosystems on Gnangara, HR368 (Hammond 2016)
- Perth Region Confined Aquifer Capacity Study: Groundwater chemistry and isotope survey, Perth, Western Australia, HR370 (Clohessy 2017)
- Lake Nowergup: Factors in declining lake and groundwater levels (Global Groundwater 2015).
You can also download a summary report describing the study and its findings.
Go to our Water Information Reporting portal to access data from the monitoring bores installed during this investigation.
Read more about our groundwater investigations by region across Western Australia.
Published journal papers
Morgan LK, Werner AD & Patterson AE 2018, ‘A conceptual study of offshore fresh groundwater behaviour in the Perth Basin (Australia): Modern salinity trends in a prehistoric context’, Journal of Hydrology: Regional Studies, vol. 19, pp 318–334, https://doi.org/10.1016/j.ejrh.2018.10.002
Siade AJ, Hall J & Karelse RN 2017, ‘A practical, robust methodology for acquiring new observation data using computationally expensive groundwater models’, Water Resource Research, vol. 53, Issue 11, https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2017WR020814
