Groundwater investigations - Mid West Gascoyne region

Details of our active and completed groundwater investigations in the Mid West Gascoyne region.
Map showing the locations of groundwater investigations in the Mid West Gascoyne region
Mid West Gascoyne groundwater investigations map

You can read about our investigations in the Mid West Gascoyne region below.

Allanooka–Casuarinas groundwater investigation

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The demand for water in greater Geraldton for town supply, industrial and agricultural uses has grown, putting pressure on the region’s water resources. Further development of the Yarragadee aquifer, which provides scheme water for greater Geraldton, had been proposed as a potential source to meet future demand. To sustainably manage the resource, we needed to increase our understanding of where recharge enters the aquifer.

We investigated groundwater resources in the Allanooka and Casuarinas subareas between Dongara and Geraldton from 2007 to 2011. We improved our knowledge of the area’s hydrogeology through:

  • developing a conceptual model
  • improving recharge estimates for the Yarragadee aquifer
  • expanding the groundwater monitoring bore network

We used the investigation’s findings and ongoing monitoring data to help develop the Arrowsmith groundwater allocation plan 2010, supporting the sustainable management of groundwater resources in the Mid West.

We completed the investigation in 2011 as part of our flagship State Groundwater Investigation Program.

What we did during the investigation

During the Allanooka–Casuarinas groundwater investigation we:

  • collected both land and air-based geophysics data, including:
    • an airborne electromagnetic (AEM) survey over an area of 2,325 square kilometres
    • high-resolution shallow seismic surveys along two east–west transects totalling 58 line kilometres.
  • completed an exploratory drilling program, installing 28 groundwater monitoring bores at 17 sites up to a maximum depth of 306 metres
  • collected and analysed 33 groundwater samples for isotopes and hydrochemistry.

Key findings and how we are using the information

 The investigation found that:

  • there are broadly two groundwater flow systems – a local, shallow, fault-bounded freshwater flow system and a subregional, deep, brackish to saline flow system
  • faulting significantly influences groundwater quality distribution – groundwater salinity contrasted significantly on either side of a major fault shown in AEM data
  • groundwater is recharged seasonally even where the depth to water exceeds 100 metres, based on continuous datalogger monitoring of new and existing monitoring bores.

Our improved understanding of the Yarragadee aquifer’s hydrogeology and ongoing monitoring will help us develop future allocation plans and licensing in the Allanooka and Casuarinas subareas.

Where to get more details

You can download the Arrowsmith groundwater allocation plan 2010.

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

  • Bore completion report for the Allanooka–Casuarinas groundwater investigation, HR316 (Schafer et al. 2011)
  • Allanooka–Casuarinas groundwater investigation, HR327 (Schafer 2016)
  • Estimates of renewable fresh and brackish groundwater resources in the Allanooka and Casuarinas subareas, HR352.
  • Groundwater monitoring review of the Yarragadee aquifer in the Allanooka-Casuarinas investigation area, HR367.

Go to our Water Information Reporting portal to access data from the monitoring bores installed during the investigation.

You can access all government-commissioned airborne geophysical surveys via the Department of Mines, Industry Regulation and Safety website and download them free of charge from ‘Geophysical Surveys’ in GeoVIEW.WA or from the Geophysical Archive Data Delivery System (GADDS).

Mid West groundwater-dependent ecosystem vulnerability

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Groundwater resources in the Mid West have come under increasing pressure from abstraction for the mining and agricultural industries. The region also has environmentally and culturally significant groundwater-dependent ecosystems.

This investigation supported the balanced management of groundwater resources by providing a better understanding of the interaction of ecosystems, surface water, and local and regional groundwater systems.

This investigation was undertaken from 2009 to 2012 as part of our flagship State Groundwater Investigation Program and the Australian Government’s Water Smart Australia program.

What we did during the investigation

Through the Mid West groundwater-dependent ecosystem vulnerability investigation we:

  • installed monitoring bores and staff gauges at 10 representative groundwater-dependent ecosystems
  • conducted aerial electromagnetic (AEM) surveys at the representative groundwater-dependent ecosystems between the Moore and Irwin rivers
  • installed loggers in bores and staff gauges to monitor water levels and salinity
  • characterised ecosystems.

Key findings and how we are using the information

We developed regional spatial layers that characterise and delineate how groundwater-dependent ecosystems in the Northern Perth Basin are connected to local and regional groundwater systems. We have used this information to help with groundwater allocation planning and licensing decisions in the Arrowsmith, Jurien and Gingin groundwater areas.

The findings of the investigation helped to develop our Bulletin HB1 – North Perth Basin: Geology, hydrogeology and groundwater resources, published in 2017.

Where to get more details

You can download Bulletin HB1 – North Perth Basin: Geology, hydrogeology and groundwater resources.

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

  • Bore completion report: Mid-West groundwater-dependent ecosystem vulnerability project stage 1 drilling program, HR306 (Boniecki & Ryan 2010)
  • Bore completion report: Mid-West groundwater-dependent ecosystem vulnerability project stage 2 drilling program, HR315 (Ryan 2012)
  • Mid-West groundwater-dependent ecosystem review: part B of vegetation description and mapping along transects (Casson 2012)
  • Analysis of subterranean groundwater-dependent ecosystems of the northern Perth Basin (Susac 2012)
  • Acquisition and processing report on downhole conductivity logging: Mid West GDE vulnerability project near Cervantes, Western Australia (GroundProbe Geophysics 2011)
  • Acquisition and processing report on SkyTEM helicopter EM survey: Mid West GDE vulnerability project near Cervantes, Western Australia (GroundProbe Geophysics 2011).

To obtain the regional spatial layers for the region, email Spatial.Data@dwer.wa.gov.au.

Go to our Water Information Reporting portal to access data from the monitoring bores installed during the investigation.

You can access all government-commissioned airborne geophysical surveys via the Department of Mines, Industry Regulation and Safety website and download them free of charge from ‘Geophysical Surveys’ in GeoVIEW.WA or from the Geophysical Archive Data Delivery System (GADDS).

Murchison palaeochannels investigation

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Groundwater resources in alluvial sands that fill ancient palaeochannels are some of the few reliable water sources in the state’s arid zones, such as the east Murchison. Tapping into these resources could help mining companies, pastoralists and towns such as Meekatharra, Cue and Mt Magnet to thrive and grow.

The Murchison palaeochannels groundwater investigation, funded through Royalties for Regions Regional Water Availability program, has pieced together the information we need as a first step to understand these hidden water resources.

What we did during the investigation

During the Murchison Palaeochannels investigation we:

  • flew a specially designed airborne electromagnetic (AEM) survey over approximately 52,000 square kilometres of palaeochannels, adding to geological and groundwater quality information sourced from more than 2,000 existing boreholes across the project area
  • worked with expert geophysicists from CSIRO to use data processing techniques specifically designed for this project to transform the AEM results into three-dimensional images and maps of the palaeochannels (which are the most detailed ever created for this area).

Key findings and how we are using the information

The mapping of the palaeochannels has simplified potential access to this ancient groundwater for productive and sustainable use by indicating where the palaeochannels are, the depth to groundwater and the quality of the groundwater stored in the riverbed sands.

The maps show potential for groundwater based on geophysics data and existing borehole data and are a guide for industry to target more detailed investigations.

Where to get more details

You can ask for a summary of the Murchison AEM survey, and a detailed CSIRO report describing how the AEM data was used to map the palaeochannels, by emailing groundwater.info@dwer.wa.gov.au.

You can access all government-commissioned airborne geophysical surveys via the Department of Mines, Industry Regulation and Safety website and download them free of charge from ‘Geophysical Surveys’ in GeoVIEW.WA or from the Geophysical Archive Data Delivery System (GADDS).

Page reviewed 8 June 2022