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 tim.munday@csiro.au w www.csiro.au

WATER FOR A HEALTHY COUNTRY