Date post: | 22-Apr-2015 |
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WATER FOR A HEALTHY COUNTRY/GOYDER INSTITUTE
Facilitating Long-term Outback Water Solutions
(FLOWS) to support mining in South Australia
Tim Munday, Mat Gilfedder, Y Ley Cooper, Tania Abdat, Kevin Cahill, Fred Leaney, Andrew Taylor and Adrian Costar
Acknowledgements
1. Traditional owners of the APY Lands
2. Richard Preece, Rex Tjami, Gary McWilliams, Andrew Cawthorn, Brian Dodson
3. DEWNR, Neil Power and Adrian Costar
4. DMITRE, Ted Tyne, Miles Davis, Steve Hill, Ian Hopton
5. Goyder Institute, Tony Minns
6. CSIRO, Glen Walker, Ian Jolly
Drivers for the Conjunctive use of Geophysics
1. Many areas of active exploration in Australia are characterised by a paucity of information on the groundwater resources present.
2. This lack of knowledge commonly extends to the aquifers present, the water they contain, variability and sustainability of the resource and its
relationship to environmental and cultural assets.
Water is identified as a major challenge facing the
development of the mining
industry
Annual water demand across the SA Resource Industry is forecast to increase from ~43,000 ML in 2010 to ~130,000 ML in 2019.
• In WA is demand is expected to increase from ~250,000 ML in 2009 to ~382,000 ML per year by 2020
Water – Key to a Sustainable Minerals Industry
• The exploration and mining industry is embracing initiatives that seek to exploit “exploration “ geophysical data sets for environmental purposes including, particularly where groundwater is concerned.
A Receptive Industry
AEM Data
Gravity Data
• Conjunctive use of exploration data sets is not always without its problems, because
• Choice of systems
• Approaches to data interpretation
are not necessarily the same.
But.....
Fast approximate
transforms
versus.......
• Conjunctive use of exploration data sets is not always without its problems, because
• Choice of systems
• Approaches to data interpretation
are not necessarily the same.
But.....
Full Inversion
• Accurately define conductivity structure, aquifer character, and
groundwater quality......
Water Resources in Arid regions of SA
Lack of knowledge and data about the location, capacity, quality and (ecological) sensitivities of non prescribed groundwater resources in the SA’s arid areas.
Groundwater resources in these region do not have a high level of modern replenishment and may already be in decline.
Knowledge gaps
1. For resource development priority areas,
– identify the location, geometry and characteristics of key aquifers,
– their potential capacity, and
– the quality and variability of the contained groundwater resources
through the integrated analysis and interpretation of geological and airborne geophysical data
2. Develop a spatial understanding of the recharge and discharge processes and rates across the priority areas
3. Desktop study groundwater dependant ecosystems, cultural assets and high value environmental assets in arid parts of State
FLOWS (Goyder - Facilitating Long-Term
Outback Water Solutions) Objectives:
Priority areas for
Stage 1
North/Western Gawler
Musgrave Block
Frome
Priority areas for
Stage 2
North Eyre Peninsula
Musgrave Province
APY Lands – Aquifer Systems
Groundwater in the APY Lands occurs in the weathered and fractured
sections of the Precambrian bedrock, palaeovalley sands, calcrete and
alluvial and aeolian sediments, and the onlapping sediments of the Officer
Basin in the south eastern part of the area
Groundwater Quality – Review (Varma 2012)
Existing AEM Data Fragmented coverage
Different systems
Philosophy: 1. Accurate system characterisation 2. Calibration 3. Common inversion approach
Using AEM to Understand Palaeovalley Structure and Relation with Current Landscape
Complex Palaeolandscape
Litho-Structural
Control
Current topo
Palaeo topo
Combine with magnetics
Conceptual Hydrogeology Pre-Pliocene landscape in the west and central Musgrave Province.
Contemporary landscape in the west and central Musgrave Province.
Examine with contemporary topography
Multi-resolution Valley Bottom Flatness index (MrVBF) (Gallant and
Dowling, 2003).
Classifies degrees of flatness using a DEM and operates at range of scales
combining the results into a single index.
Combine with regional topographic trends
An offset Palaeovalley thalweg
Contemporary Landscape Reflects Palaeolandscape
AEM Palaeovalley vs Contemporary Topography
Hydrogeological framework model
Magnetics informs the framework model
Palaeozoic sediments in in Levenger
Graben
Upscaling
Framework and contemporary sand cover
Framework and Hydraulic Gradient
Groundwater residence using isotopes and anthropogenic gases
3
1
|
3H/3He
85Kr
CFC's, SF6
36Cl
39Ar
14C
81Kr
4He
0.1 1 10 100 1000 10000 100000 1000000 10000000
Approximate Groundwater Age (years)
Framework and 4He
Inferred groundwater flow paths
Trends across APY Lands
In the northern area, groundwater wells are predominantly screened to the regolith of the Precambrian basement rock of the ranges
– Higher rates of recharge – direct and diffuse
– A modern groundwater age - mean residence time <50 yrs
– Fresh groundwater associated with localised recharge from episodic rainfall events
In the central/southern area away from the ranges, groundwater wells are screened to Tertiary and Quaternary sediments
– Lower rates of recharge where diffuse recharge dominates
– Groundwater ages derived from 14C, high concentrations of 4He and higher Cl– indicate much older groundwater
Method
1. It has been tested in the
Musgrave province of South
Australia.
2. Has application in other parts
of outback South Australia,
including the SAA Lands, but
also other parts of the
Alinytjara Wilurara NRM
Region.
3. Also be applicable to the
Northern Eyre Peninsula.
Follow-up Hydrogeological Investigations: A Possible Workflow
Physical Hydrogeology
•A framework for ground investigation
• Target – industrial scale groundwater resource?
Ground EM soundings to locate thick sequences of sediment Drilling Resource
Characterisation
Summary (cont)
1. Conjunctive use of exploration geophysical data sets providing input into conceptual hydrogeological model development
Critical data sets
– AEM
– Mag
– DEM
2. Re-Processing AEM with common inversion kernels providing the basis for comparison of results from different areas, but accurate system description is important –
Will not generate seamless maps
Summary
1. Encouraging companies and contractors to ask for and supply that information, even though water/aquifer characterisation maybe less important in the first instance!
2. Work with companies on extending data acquisition – not expensive, but information will add significant knowledge ref groundwater and geology
3. Linking data with an understanding of groundwater age, and recharge through collection of isotopic and tracer data is important -> better conceptual hydrogeological models
Key Gaps in Knowledge
Very little information on the hydrogeology of the palaeovalley aquifers
– Materials
– Transmissivity
– Water quality
– Quantity
– Yields
What/where next....?
Using Geophysics ...
Tells us about aquifers....
Further Data Acquisition Options/Opportunities - Build on Exploration Company activity
Extend Survey lines
Add new lines
•$ Cost relatively low – eg
10kms for ~$1500-2000
•No Mob costs
•Value to State
Thank you Tim Munday
CSIRO Earth Science and Resource Exploration t +61 8 6436 8634
e [email protected] w www.csiro.au
WATER FOR A HEALTHY COUNTRY