Product catalogue
Exploring for the Future-Integrated hydrogeological investigation of the Koolpinyah Dolostone Aquifer: Howard East, Northern Territory
This report presents key results from the Howard East project conducted as part of Exploring for the Future (EFTF), an Australian Government funded geoscience data and information acquisition program. The four-year (2016–20) program focused on better understanding the potential mineral, energy and groundwater resources in northern Australia.
Groundwater is an essential part of Darwin’s water supply and is sourced from the Koolpinyah Dolostone Aquifer (KDA) at the Howard East Borefield (HEB) and McMinns Borefield, which are ~25 km to 30 km southeast of Darwin. Previous work suggests that electrical conductivity anomalies observed in airborne electromagnetic (AEM) data within 5 km of HEB may be caused by saline groundwater within the KDA that is separated from HEB by dykes and other geological features that effectively compartmentalise the aquifer (Fell-Smith & Sumner, 2011; Tan et al., 2012). Nevertheless, concerns have grown that increased groundwater use may result in migration of saline groundwater toward HEB, which could compromise the groundwater resource.
We collected groundwater chemistry including isotopes, time-series groundwater salinity, AEM, and induction and gamma data to better understand the complexities of the KDA. We show that groundwater in the KDA typically has a fresh Mg-Ca-HCO3 type composition, as is expected for a dolomitic aquifer. Highly saline Na-Cl type groundwater with a composition similar to seawater exists at some locations as well as groundwater with a mixed composition. These findings confirm previous interpretations for the area (e.g. Fell-Smith & Sumner, 2011). We sampled saline groundwater on the opposite side of two dolerite dykes to HEB to its northeast. Age dating results for this sample cannot be used to determine whether this saline groundwater represents relict seawater or whether groundwater at this site is in hydraulic connection with the modern ocean. Our groundwater chemistry results also show that saline intrusion is occurring northwest of HEB.
AEM data were collected to better characterise geological and hydrogeological features in the area. Estimates of bulk conductivity of the subsurface were derived by inverting AEM data using both deterministic and stochastic methods. Using these AEM inversions and other hydrogeological information, we characterised high-conductivity anomalies within 5 km of HEB and the upper surface of unweathered dolerite in the two dykes northeast of HEB. We interpreted conductivity anomalies as pyritic shales, although drilling is required to investigate the salinity of groundwater in the KDA in this area. Where we were able to resolve the upper surface of unweathered material in the two dykes using the AEM, we found that it commonly occurs below sea level. Characterising the geometry of these dykes will aid in assessing their role in aquifer compartmentalisation.
Our findings contribute to building a robust conceptual understanding of the KDA and will guide future investigations into the groundwater system.
A number of other products exist for the EFTF Howard East project. The findings of this report are integrated with hydrodynamic analyses undertaken by Woltmann (in prep.) and reported in Haiblen et al. (2020). Hydrochemistry data presented here are contained in McGrath-Cohen et al. (2020), water level and salinity monitoring data can be found in Turner et al. (2020), AEM data are in Ray et al. (2020b), and induction and gamma data are in Tan et al. (2020).
Simple
Identification info
- Date (Creation)
- 2020-06-01
- Date (Publication)
- 2021-02-22T02:50:01
- Citation identifier
- Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/134052
- Citation identifier
- Digital Object Identifier/http://dx.doi.org/10.11636/Record.2020.057
- Cited responsible party
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Role Organisation / Individual Name Details Author Haiblen, A.M.
Author Symington, N.J.
Author Ray, A.
Author Parige, R.H.
Author McGrath-Cohen, E.S.B.
Author Gow, L.J.
Author Leplastrier, A.
PSCD Internal Contact
- Name
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Record
- Issue identification
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2020/057
- Purpose
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Interpretive product for the groundwater EFTF Howard East project.
- Status
- Completed
- Point of contact
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Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Haiblen, A.
MEG Internal Contact
- Spatial representation type
- Topic category
-
- Geoscientific information
Extent
Extent
))
- Maintenance and update frequency
- As needed
Resource format
- Title
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Product data repository: Various Formats
- Website
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Data Store directory containing the digital product files
Data Store directory containing one or more files, possibly in a variety of formats, accessible to Geoscience Australia staff only for internal purposes
- theme.ANZRC Fields of Research.rdf
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EARTH SCIENCES
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- Project
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EFTF
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- Project
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Exploring For The Future
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- Discipline
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Groundwater
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- Place
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Koolpinyah Dolostone Aquifer
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- Theme
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Seawater Intrusion
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- Keywords
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Published_External
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Resource constraints
- Title
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Creative Commons Attribution 4.0 International Licence
- Alternate title
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CC-BY
- Edition
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4.0
- Access constraints
- License
- Use constraints
- License
Resource constraints
- Title
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Australian Government Security ClassificationSystem
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
- Language
- English
- Character encoding
- UTF8
Distribution Information
- Distributor contact
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Role Organisation / Individual Name Details Distributor Commonwealth of Australia (Geoscience Australia)
Voice
- OnLine resource
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Download the Record (pdf) [5.7 MB]
Download the Record (pdf) [5.7 MB]
- Distribution format
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pdf
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Resource lineage
- Statement
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This report contains groundwater chemistry including isotopes, time-series groundwater salinity, AEM, and induction and gamma data, and hydrogeological interpretations based on these datasets.
Metadata constraints
- Title
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Australian Government Security Classification System
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
Metadata
- Metadata identifier
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urn:uuid/39a8e8a2-ac87-4174-ab42-6d12152cb1af
- Title
-
GeoNetwork UUID
- Language
- English
- Character encoding
- UTF8
- Contact
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Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Haiblen, A.
MEG Internal Contact
Type of resource
- Resource scope
- Document
- Name
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GA publication: Record
Alternative metadata reference
- Title
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Geoscience Australia - short identifier for metadata record with
uuid
- Citation identifier
- eCatId/134052
- Date info (Creation)
- 2019-04-08T01:55:29
- Date info (Revision)
- 2019-04-08T01:55:29
Metadata standard
- Title
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AU/NZS ISO 19115-1:2014
Metadata standard
- Title
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ISO 19115-1:2014
Metadata standard
- Title
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ISO 19115-3
- Title
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Geoscience Australia Community Metadata Profile of ISO 19115-1:2014
- Edition
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Version 2.0, September 2018
- Citation identifier
- https://pid.geoscience.gov.au/dataset/ga/122551