In the Gingin area, 100–200 kilometres north of Perth, the climate is drying and demand for groundwater resources for agriculture is increasing.
We investigated the North Gingin groundwater resources to improve monitoring, update our hydrogeological understanding and make new recharge estimates across the plan area – particularly in the regionally significant coastal Leederville and Yarragadee aquifers.
Our updated recharge estimates suggest that additional groundwater may be available from confined areas of the Gingin coastal Leederville and Yarragadee aquifers. We will use these revised estimates as part of future allocation planning in the area.
This investigation ran from 2012 to 2015 as part of our flagship State Groundwater Investigation Program.
What we did during the investigation
Through the North Gingin investigation we:
- drilled 8,763 metres and installed 29 groundwater monitoring bores to a maximum depth of 1,022 metres
- analysed the water chemistry of 36 bores
- used three methods to estimate recharge: chloride mass balance, watertable fluctuation and Darcy’s Law
- estimated the location of the seawater interface using new bores and analytical methods.
Key findings and how we are using the information
Key findings from the investigation include:
- We better understand where the Gage Sandstone is present. This part of the Yarragadee aquifer has lower bore yields and reduced throughflow. We will use the updated regional conceptualisation from the drilling program to update future versions of the Perth Region Aquifer Modelling System (PRAMS).
- New recharge estimates suggest the presence of additional groundwater from the Gingin coastal confined Leederville and Yarragadee aquifers. We will factor the updated recharge estimates into future Gingin allocation plan reviews.
- The seawater interface is 3 to 5 kilometres onshore in the southern coastal superficial subareas, about 1 kilometre onshore in the northern coastal superficial subareas, and likely to be 10 to 15 kilometres offshore in the confined aquifers. We can use information from the bores installed during the investigation to monitor seawater intrusion in the aquifers over time.
We used these findings to help develop the Gingin groundwater allocation plan 2015. We will continue to monitor the new bores to sustainably manage groundwater in the area.
Where to get more details
You can download the Gingin groundwater allocation plan 2015.
You can ask for copies of the internal technical reports for this investigation by emailing groundwater.info@dwer.wa.gov.au. These include:
- North Gingin bore completion report, HR353 (Tuffs 2016)
- Geology and hydrogeology of the north Gingin area, HR411 (Tuffs 2019)
- Northern Perth Basin Bulletin.
Go to our Water Information Reporting portal to access data from the monitoring bores installed during the investigation.
Read more about our groundwater investigations by region across Western Australia.
