Groundwater investigations - Statewide

Details of our active and completed statewide groundwater investigations.
Map of statewide groundwater investigations
Statewide groundwater investigations map

You can read about our statewide investigations below.

Statewide seawater interface investigations

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Coastal aquifers are a significant source of water for industry, drinking, public open space and a range of other uses. In coastal aquifers, dense salty water from the ocean meets the fresh water flowing out to sea below the surface of the land. This zone naturally occurs and is called the seawater interface.

The seawater interface can move inland if rainfall and groundwater recharge decline, or too much groundwater is abstracted. To maximise groundwater use without risking aquifers going saline, we need to know more about the location and movement of the seawater interface in many coastal areas.

Statewide seawater interface investigations, funded by our flagship State Groundwater Investigation Program (SGIP), are improving monitoring networks and giving us a better understanding of the seawater interface in priority areas across the state. These investigations began in 2016 and are ongoing around Western Australia.

What we are doing for these investigations

Statewide seawater interface investigations provide information, science and evidence-based advice to enable coastal groundwater resources to be used to their full potential, without going saline. The projects:

  • use a combination of drilling, groundwater sampling and downhole and ground-based geophysics to measure and monitor the seawater interface
  • install appropriate seawater interface monitoring in priority groundwater areas across the state
  • assess new methods to effectively and efficiently investigate and monitor seawater interfaces.

So far we have:

  • completed or are conducting investigations in the Cockburn, Peel Coastal, Myalup, Bunbury, Busselton-Dunsborough and Esperance areas
  • begun scoping in the Broome-Skuthorpe and La Grange areas
  • planned future projects for West Canning and Derby.
Statewide seawater interface map

Key findings and how we are using the information

In the Cockburn area we have:

  • mapped the location of the seawater interface
  • used our new knowledge of the extent of the seawater interface to refine the seawater interface risk zone and local licensing rules in the Cockburn groundwater allocation plan
  • through the monitoring so far, found that the seawater interface moves seasonally – inland in summer and receding during winter/spring
  • continued to monitor the seawater interface to assess any inland progression from abstraction and climate change.

In the Peel Coastal area we have:

  • found hypersaline groundwater related to Peel Inlet in the east of the area that may be a higher risk to resource condition than seawater (ongoing monitoring is required to determine if this hypersaline groundwater is mobile)
  • captured preliminary monitoring and logged data to indicate the ocean-side seawater interface has moved inland (ongoing monitoring is required to confirm if this is seasonal or if there is persistent inland seawater interface movement).

In the Esperance area we have:

  •  identified the thickness and extent of fresh water in the superficial aquifer.

Findings from these investigations will help us manage seawater intrusion risks as part of allocation planning and licensing in priority areas around the state.

Where to get more details

You can request copies of the internal technical reports for this investigation by emailing groundwater.info@dwer.wa.gov.au.

Reports completed to date include:

  • Cockburn seawater interface drilling project 2018 – Bore completion report, HR408 (DWER 2019)
  • Peel seawater interface drilling project –  Bore completion report, HR409 (DWER 2020)
  • Esperance seawater interface drilling project – Bore completion report, HR18 (DWER 2020)

You can access data from the monitoring bores installed as part of this investigation at our Water Information Reporting portal.

Groundwater telemetry trial

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We collect groundwater monitoring data to sustainably manage Western Australia's groundwater resources. Automatic groundwater-level data loggers are installed in about 700 bores across the state. We collect manual measurements from an additional 2,000 bores. Many bores are in remote locations that are difficult to access.

We began a groundwater telemetry trial in 2019, funded by the State Groundwater Investigation Program. To test their application and efficiency, we have installed 40 telemetered data loggers in the Peel, Gingin, Broome and Kununurra areas. If the trial is successful, we will roll out groundwater monitoring telemetry in priority areas across the state. We aim to improve data availability and reduce data collection efforts for groundwater monitoring.

You can ask for more information on the groundwater telemetry trial by emailing groundwater.info@dwer.wa.gov.au.

Groundwater modelling optimisation partnership

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We use numerical groundwater models to support our allocation planning and licensing decisions. We use these highly complex and resource-intensive tools when:

  • groundwater resources have or are reaching their sustainable yield
  • there is a risk to the resource or its dependent values
  • there are multiple competing demands on the resource
  • simpler analytical solutions are not suitable.

This project provided workflows, tools and modelling capacity to enable more efficient modelling practices and reduce run times for regional-scale groundwater models. It is a partnership between our SGIP project, the Water Corporation and the University of Western Australia.

What we did during the investigation

The project developed a series of ArcGIS tools based on the Perth Regional Aquifer Modelling System (PRAMS) v3.5.2. The tools allow model input files for MODFLOW to be generated and output files to be processed and visualised within the ArcGIS platform.

Key findings and how we are using the information

This project developed a method to generate a robust surrogate model for PRAMS with significantly reduced model run times. Our team has used the surrogate model for detailed model calibration and predictive uncertainty. The research was published in the Water Resources Research journal.

This project has improved:

  • how we develop and use numerical groundwater models
  • modelling efficiency
  • confidence in model outputs through uncertainty analysis.

It has also built our capacity, and that of our project partners, to undertake advanced modelling techniques.

Where to get more details

Siade AJ, Cui T, Karelse RN & Hampton C 2020, ‘Reduced-dimensional Gaussian process machine learning for groundwater allocation planning using swarm theory’, Water Resources Research, vol. 56, issue 3: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019WR026061

You can request more information on this project by emailing groundwater.info@dwer.wa.gov.au.

Page reviewed 8 June 2022