Perth Region Confined Aquifer Capacity (PRCAC) study
World class WA groundwater science
The $7 million Perth Region Confined Aquifer Capacity (PRCAC) study is a four-year project that aims to improve our certainty of how much water can be extracted from Perth's deep aquifers without impacting their long-term sustainability.
The study commenced in 2012 and combines conventional groundwater investigations, innovative science partnerships with leading research institutions, and an ongoing collaboration with the Water Corporation.
The project builds on the excellent work to date by the Department of Water and its predecessors in investing in science to understand the aquifer systems below Greater Perth.
The importance of Perth's groundwater
Today, the city uses more than 430 billion litres of water a year from the ground beneath our feet. This water is very important to local governments and the urban development and horticulture industries. This water is the reason we have ovals and parks for sports and recreation, places that make our City such a great place to live. It is the reason that we have fresh food grown here on our doorstep.
The Gnangara and Jandakot groundwater systems are also a major source of water for public supply, contributing in 2013-14 around 40 per cent of the water delivered to Perth's households and businesses through the Integrated Water Supply Scheme.
The Department of Water is continually improving the way it manages the Perth's groundwater resources and its multiple uses in a drying climate.
Our management of groundwater abstraction in recent years to reduce the impact of the drying climate is producing real, positive outcomes that include limiting abstraction from environmentally sensitive areas of the superficial aquifer and taking water for public water supply mostly from the deep aquifers.
To carry out this advanced resource management, we are updating our knowledge of the complex groundwater system with the aim of ensuring long term productivity of the resource.
Innovative research and partnerships
As part of the PRCAC study, through $1.5 million in research agreements with Curtin University and the University of Western Australia, we will apply new methods to verify groundwater modelling – utilising equipment not currently available commercially.
This includes using the Magnus Cray supercomputer at the Pawsey Centre in Bentley.
In the first two years of the PRCAC study the Department of Water completed several data collection programs that covered over 7,000 square kilometres of the Perth region using geophysical equipment mounted to planes and helicopters.
We have used information from these airborne surveys to help us target the next stage of more detailed investigative work.
Exciting finds to date
One of the goals of the $7 million Perth Region Confined Aquifer Capacity project is to see whether we can optimise the way we abstract and use water from the Gnangara system, including new locations to draw water from deep aquifers that have less impact on the system.
Through recent seismic and electromagnetic surveys we already have a better understanding of the groundwater flow in the north western Gnangara system.
Evidence from our recent scientific work defining the aquifers on either side of an important geological formation known as the Badaminna fault line has revealed information about potential water capacity and groundwater recharge not previously known.
This exciting revelation is supported by other work and reveals water on the western side of the fault line is recharged from a different area to the water on the eastern side. All of this indicates a potential new area of the groundwater system where it is separated from other parts of the system.
The department is now building on this work and installing groundwater monitoring bores to measure the water levels chemistry and age. This will help us work out if the aquifers are connected to the eastern side of the fault, and where recharge to this area of the system is coming from.
As we learn more about this groundwater area and its unique characteristics we will assess the potential volume of water that could be sustainably abstracted for public or private water supply. This work will be completed by 2017. Water from the Leederville and Yarragadee aquifers is mostly used for the Integrated Water Supply Scheme, so water in this area north of Yanchep would eventually support future growth in this area.
What will the project achieve?
The information gained through PRCAC will be used for, but not limited to:
- identify the locations that are suitable for the future expansion of the State Government's Groundwater Replenishment Scheme – a key component of climate resilience for scheme water supplies
- support sustainable use of the Gnangara groundwater system which currently supplies around 45 per cent of Perth's total estimated water use
- further update abstraction strategies for public and private water supply that minimise impact on wetlands and groundwater dependant ecosystems and maximise use of the deeper confined aquifers without impacting on water quality.
- protect existing users of Perth groundwater from saline intrusion
- help make decisions about land use and development that optimise recharge of local and deep aquifers.