Recharge and leakage through
aquitard barriers
Dr Wendy Timms & P1B team National Centre for Groundwater Research & Training
National Water Commission and Australian Research Council funds Commenced in July 2009
Flinders Uni + UNSW + ANU + UQ + many partners
Five Research Programs:
• Innovative Characterisation of Aquifers and Aquitards
• Hydrodynamics and Modelling of Complex Groundwater Systems
• Surface Water ‐ Groundwater Interactions
• Groundwater‐Vegetation‐Atmosphere Interactions (GVI)
• Integrating Socioeconomics, Policy and Decision Support
Groundwater @ UNSW Consulting ‐ WRL projects team
•Brett Miller, Dr William Glamore, Grantley Smith, Dr Wendy Timms, Alexandra Badenhop, Conrad Wasko, Duncan Rayner and others
Research ‐ NCGRT through Connected Waters Initiative (Faculties of Science & Engineering)
•Prof Acworth, Prof Baker, A/Prof Bryce Kelly, Dr Martin Andersen, Dr Matt McCabe, Dr Wendy Timms, Dr Gregoire Mariethoz
•Post Docs: Dr Anna Greve, Dr Cath Jex, Gyanendra Regmi, Josh Larsen, Hamid Roshan, Adam Hartland
•PhD Scholars: Adam King, Mark Peterson, Peter Graham •4th Year Honours: Kathryn Ludowici, Ed Kearney, Melissa McDonnell, Jessica Wheatley, Blake Bambrook, Chris Farley, Hannah Walmsley, Alex Rogan, Bilal Khan, Aidan Fitzallen
•Technical: Mark Whelan, Sam McCulloch, Hamish Studholme
Outline 1.
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Baseline groundwater quality
Integrated vadose zone-groundwater studies
3D geological architecture
Disconnected waters?
Breeza research site
Questions for the future!
Skipping this time – surface water & groundwater connectivity, innovations,
awards & international peer reviewed publications!
Baseline groundwater quality
• Defined how groundwater levels and salinity vary spatially and over time
• Groundwater salinity can change significantly over time
• Major ions, EC, pH only – need to look at nitrate, organics & gases
• Grower & community monitoring
• Interview/surveys and 3 workshops held with growers
• 69 growers participated in groundwater testing
• Best Management Practice for irrigation bores monitoring
• Recommendations & cost estimates for strategic on-going monitoring
• Need for growers to monitor their water at point-of-use
• Need for groundwater quality testing at key monitoring bores
• Maps & limited statistics & database produced
Reports are available here:
www.namoi.cma.nsw.gov.au
www.wrl.unsw.edu.au/namoi
Groundwater salinity changes
ECaverage 1980‐1999
ECaverage 2000‐2009
No. of GW pipes
673 total pipes
105 with available data 57 EC stable
21 EC up >10% 27 EC down >10% This map Pipe 2
(deep)
Worst case groundwater salinisation
Groundwater levels
0
SWL mbCasing
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Evidence for significant groundwater quality change over time at some sites
At one site in the Namoi, groundwater at 80 m depth has become too saline for irrigation of cotton (7,700 µS/cm ANZECC). Was a fresh alluvial aquifer. Change occurred sometime between mid and late1990s Why?
10
036166-1
20
036166-2
30
036166-3
40
16000
EC uS/cm
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ƒ
12000
Groundwater salinity
036166-2 (77.4 - 80.4 m depth)
8000
4000
0
036166-1 (45.7-48.7 m depth)
036166
(pipe unknown)
036166-3 (95.7 - 98.7 m depth)
7 5 7 7 79 81 8 3 8 5 87 89 9 1 9 3 95 9 7 9 9 01 03 0 5 0 7 09
1 9 1 9 19 19 1 9 1 9 1 9 19 1 9 1 9 1 9 1 9 1 9 20 20 2 0 2 0 2 0
GW036166.grf
Integrated vadose zone‐groundwater studies
Cryon plain study with Rick Young and Neil Huth
Soil & groundwater investigations, APSIM modelling, local groundwater flow model
Deep drainage is greater than recharge due to large soil moisture storage in 20 m thick vadose zone
Shallow soil salinity surveys underestimate total storage
eg. 30 t/ha to 1.5 m depth as NaCl
~300 t/ha to 10 m depth Salt leached downwards during episodic events (eg
1998)
but discharge to Namoi River not possible in this area
No direct evidence of groundwater recharge over short monitoring period, but potential for aquifer salinisation
Disconnecting waters?
Aquitards can disconnect waters
• limit recharge & leakage
• limit migration of contaminants/salts
Questions…
• Are clay sediments and cap-rocks disconnecting water?
•How much water is stored in aquitards?
•How much water leaks through aquitards?
•Is consolidation and surface settlement a concern?
•How much salt could leach from thick aquitards?
•What is the capacity of aquitards to lock away contaminants ?
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nutrients, agrichemicals (Liverpool Plains, Australia)
metals, organics and radioactive leachate (Canada)
•Does the salts leached from the aquitard impact on hydraulic properties of aquitards?
Aquitard research sites – Namoi catchment
Three sites in the Upper Mooki valley of the Liverpool Plains
Recharge sources based on MODFLOW model (Zone 3 long term average)
11 GL/y diffuse recharge through plains (70%)
4 GL/y
irrigation returns
2 GL/y
stream leakage
0.7 GL/y through Breeza constriction
0.4 GL/y flood recharge
1. Breeza farm (NSW DPI collaboration)
•watertable ~18m depth
•Irrigation bores, low salinity
Normans Rd
2. Cattle Lane
•watertable 0-2 m depth
•No irrigation bores, high salinity
3. Normans Road (Super Science site,
Office of Water collaboration?)
•aquifer salinity increasing – why?
•watertable ~18m depth
BreezaPullaming
Study area
Cattle Lane
- Yarramanbah
3D architecture of aquitards
Red = aquitard
Collaboration with Bryce Kelly, Josh Larsen
and Rachel Blakers (ANU), Chris Farley &
Anthony Bowling - Honours students
Mooki catchment stratigraphy data
NOW monitoring bores
NCGRT drilling & coring
Selected geophysical logs
Are aquitard deposits laterally continuous at the
surface, or at depth?
Aquitard volume & aquifer contact area?
Can 3D architecture of alluvial clayey silt
deposits be predicted with geostatistics,
hydrostratigraphy and/or geomorphology
techniques?
Breeza farm
Cattle Lane site
Breeza site
Info on web:
http://www.connectedwaters.unsw.edu.au/technical/research/projects/projects_aquitards_namoi.html
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Collaboration with NSW DPI
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Focus on moisture & water between
surface through low permeability sediments
to ~40 m depth
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Assess interactions with underlying aquifer
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New piezometers, geophysics casing,
weather station, gravity station
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Extends work from a decade ago
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Not related to mining or Namoi water study
Clay sediment coring
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Ground surface to 40 m depth
Completed in May 2011 at Breeza and Norman’s Road sites
100 mm diameter minimally disturbed cores, 1.5 m lengths in clear PET liners
What’s a centrifuge permeameter?
A column containing a porous sample
that is subjected to centrifugal force, with
specific flow conditions at the top and
base.
A modified geotechnical centrifuge,
accelerated gravity version of a
permeameter or triaxial cell.
Rapid, repeatable testing for low
permeability samples
Tests for soil & rock:
•Permeability & recharge rates
•Extraction of pore water
•Effective porosity
•Consolidation & settlement
•Contaminant retardation-sorption
•Water retention curve of soils
•Physical models of barrier systems
NCGRT core permeameter centrifuge
@ UNSW WRL
Core Permeameter module
Swing box beam module
Available for researchers and industry
studies
Cap rock integrity?
Water & gas permeability?
$0.8 million facility funded by ARC & NWC
Unique international facility – only centrifuge
testing environment for 65 & 100 mm diam
drill core at up to 875g @ 0.7 m radius
Design modified from CPUS permeameter
(McCartney 2007) with advanced
instrumentation for in-flight measurements
developed by UNSW
Advanced DAS systems developed by
UWA Centre for Offshore Foundations
Degree of disconnection?
with Gyanendra Regmi (Postdoc) , Blake Bambrook (Honours student)
Preliminary permeameter results
•10‐9 to 10‐11 m/s for clays at ~24 m depth at Breeza
•Vertical leakage estimations, if laterally continuous clay
Porewater chemistry of aquitards
Collaboration with Dr Michael Smith (GA-NOW)
Honours students Ed Kearney & Hannah
Walmsley
•Porewater salinity via 4 methods:
• 1:5 dilutions, saturation extract
• squeezing at up to 30 MPa
• centrifuging at ~3000 RPM
•Analysis of only ~1 mL of water!
Preliminary findings:
•Dilutions - relatively high TDS values
•Squeezing and centrifugation - similar TDS
values for most samples
•Decreasing TDS with increasing extraction
time/pressure?
•Impact of compaction & pressure on
geochemistry?
•Is this saline water mobile downwards?
•Aquifer capacity for dilution?
Questions for the future!
Diffuse recharge through plains vs. other sources? Really integrated studies of deep drainage & recharge (same areas/sites, same time periods, gap between 5 and 20 m)
Are the clay aquitards are once off source of water and/or salt? Baseline groundwater quality? expand monitoring to rock areas & other parameters (organics, gas)
Recommendations for groundwater being presented in Narrabri today:
1.Fund background water quality surveys
2.Record deep drainage at the shallow water table
3.Investigate the viability of managed aquifer recharge
4.Support the development of collective impact modelling
5.Support investigation of the influence of groundwater extraction on river flow
6.Extension, Communication and Education
Complexity is presented by the relationship between the
aquifer, aquitards and in some areas, the underlying coal and gas deposits.
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