Investigation of surface water groundwater exchange in the...

1

Investigation of surface water groundwater Investigation of surface water groundwater exchange in the Maules Creek catchmentexchange in the Maules Creek catchment

ByBy

M.S. AndersenM.S. Andersen

THE UNIVERSITY OF NEW SOUTH WALESSchool of Civil and Environmental Engineering

WATER RESEARCH LABORATORYAustralia

Co-workersIan Acworth (WRL/CWI)

Beatric Gambastiani (BEES/CWI)

Anna Greve (WRL/CWI)

Bryce Kelly (BEES/CWI)

Andrew McCallum (WRL/CWI)

Karina Meredith (ANSTO)

James Patterson (WRL/CWI now UTS)

Gabriel Rau (WRL/CWI)

Peter Serov (DWE)

Wendy Timms (WRL/CWI)

2

Further information:

www.connectedwaters.unsw.edu.au

Updated almost weekly!

General news & articles

Fact sheets

Research updates

Poster downloads

Publication lists

Journal abstracts

Team & alumni

OutlineBackgroundThe Maules Creek project

- Hydrographs- Hydrogeology- Stable Isotopes- Heat tracing- Stream bed chemistry- Stygofauna- Modelling the bigger picture- Climate data- Resistivity tomography- Deep drainage & mini-lysimeters

3

Background

Allocation of water resources

• Groundwater and surface water allocated independently

→ Overallocation of the resource

• Confilcts between users

• Impacts on river flow

• Impacts on the aquatic environment

4

High groundwater levels (winter) and/or low stream flow

High stream flow due to flooding or dam releases

Groundwater extractionWinter et al. 1998

Surface water - groundwater Interactions: The basics

Change in time:- location- direction- magnitude

Drawdown, ∆s ~ 2 m

Total saturated thickness ~ 50 m

Relative decrease in saturated thickness ~ 4%

Potential implications for stream flow

5

How do we measure surface water groundwater interactions ?

• Hydrograph analysis – Analysing changes in stream flow

• Physical methods – Hydrogeological methods– Heat

• Hydrochemical methods & tracers– Natural water chemistry– Injected tracers

Hydrogeologic investigations- Stream and groundwater level measurements

Winter et al. 1998

6

River deposits - are complex

Freeze and Cherry 1979

Hydrometric measurements- Problem of connectivity

Winter et al. 1998

X

7

Project aims• Study dynamics of surface water groundwater

exchange in a catchment with extensive groundwater abstraction and irrigation

• Develop tools and methodologies for mapping and quantifying the water exchange

→ Experimental work in a small catchment on the Namoi River, NSW

Study catchment

8

Groundwater extraction zone

Zone of perennialpools

Maules Creek

Ho

rsea

rm C

reek

Mid

dle

Cre

ekNam

oi R

iver

Nam

oi River

Maules Creek catchment

Ho

rsM

iddl

e C

reek

River

Quarternary- Clay- Sand- Gravel

Permian- Volcanic

deposits

Permian- Sandstones- Shales- Coal measures - Conglomerates

9

South-west North-east

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Distance, m

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

Ele

vatio

n, m

P1

P2

P1

P2

P1

P2

P3

P1

P1 P1

P1

P1

P2

P1

P1

P2

P1

Clays

Bedrock: sandstonesshales/coals

Sands and gravels

Geological cross-

sections

Maules Creek cross-section

Northern cross-sectionWest East

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Distance, m

100

120

140

160

180

200

220

240

260

Ele

vatio

n, m

River

P1

P2

P1

P2

P3

P1

P2

P3

P1

P1

P2

P1

P2P1

P1

P1

Sands and gravels

Clays

Bedrock: sandstones/shales/coals

Namoi River

Namoi River

0

500

1000

1500

2000

24/02/06 24/05/06 24/08/06 24/11/06 24/02/07Date

Str

ea

m fl

ow [M

L/d

]

Namoi at Boggabri (upstream)

Namoi at Turrawan (downstream)

Dam release

Flash flood due to rain

M

Ho

rsea

rm C

reek

Mid

dle

Cre

ekNam

oi R

iver

Nam

oi River

Turrawan

Boggabri

Stream flow: Namoi River

10

Stream flow loss: Namoi River

Upstream

Downstream

CumulativeLoss

M

Ho

rsea

rm C

reek

Mid

dle

Cre

ekNam

oi R

iver

Nam

oi River

Stream flow: Maules Creek

0

2

4

6

8

10

24/02/06 4/06/06 12/09/06 21/12/06 31/03/07Date

Str

eam

flo

w [M

L/d

]

Maules Creek

Elfin crossing

Maules Creek

Effects of nearby pumping ?

11

Hydrograph GW030233away from streams

215

220

225

230

Feb

-75

Feb

-77

Feb

-79

Feb

-81

Feb

-83

Feb

-85

Feb

-87

Feb

-89

Feb

-91

Feb

-93

Feb

-95

Feb

-97

Feb

-99

Feb

-01

Feb

-03

Feb

-05

Wat

er L

evel

(m

b. D

atum

)

Upper aquifer, 15.9 m.b.s.

M iddle aquifer, 55.5 m.b.s.

Lower aquifer, 84.4 m.b.s.

Hydrograph GW036093close to Maules Creek

215

220

225

230

Feb

-75

Feb

-77

Feb

-79

Feb

-81

Feb

-83

Feb

-85

Feb

-87

Feb

-89

Feb

-91

Feb

-93

Feb

-95

Feb

-97

Feb

-99

Feb

-01

Feb

-03

Feb

-05

Wat

er L

evel

(m

b. D

atum

)

Upper aquifer, 22.8 m.b.s.

M iddle aquifer, 53.1 m.b.s.

Lower aquifer, 68.5 m.b.s.

M

Ho

rsea

rm C

reek

Mid

dle

Cre

ekNam

oi R

iver

Nam

oi River

Bore36093

Groundwater hydrographs

Bore30233

215

220

225

230

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

Recharge ?

Groundwater levelsin well close to river

Flow in theNamoi River

Upper aquiferat 16 m

Lower aquiferat 84 m

River recharge events ?

12

30129

30130

30131

30132

30133

30134

30231

3023230233

3023430235

3023630237

30446

30447

36003

36004

36005

36093

36094

36096

36164

3618636187

967137

Maules Creek

Hydrograph GW030231/2

212

222

232


212

222

232


225

235

245


225

235

245


212

222

232


210

220

230


210

220

230


230

240

250

Well hydrographs (DNR)X-axis: time (+30 yrs.)Y-axis: Head (20 m)

Upper piezometersMiddle piezometersLower piezometers


230

240

250


220

230

240


213

223

233


213

223

233


210

220

230


210

220

230

233.8

243.8

255.6

253.3

218.5

2

245.2

253.2

222.0

221.8

237.6

218.3

243.2

221.6245.0

219.0

222.8

245.4

222.0

227.9

224.9

240.7

229.4

232.1

233.1

Maules Creek

2000 m

Groundwater levels in the upper aquifer (<30 m) including surface water elevations August 2006

Δh ~ - 0.6 m

Δh ~ - 4.4 m

Δh ~ - 0.1

218.2

13

HeadsMaules Creek transect

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Distance, m

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

Dep

th b

elow

sur

face

, m

Clay

Sand/Gravel

Clay

Sand/Gravel

Clay

Basalt

Clay

GravelClay

Gravel

Clay

Gravel

Clay

RockAcid Igneous

Clay

Gravel

Clay

Gravel

Clay

GravelRock

Rock

Clay

GravelClay

GravelClay

GravelClay

Gravel

ClayRockRockBedrock

Clay

Gravel

Clay

Gravel

Clay

Gravel/sandRockBasalt

Loam

Clay

Gravel

Clay

Rock

Gravel/clay

Clay

Gravel

Clay

Gravel

ClayGravel

ClayGravel

Clay

Rock

Clay

Gravel

ClayGravel

ClayGravel

ClayBedrock

ClayGravel

ClayGravel

ClayGravel

ClayGravel

ClayGravel

ClayGravel

ClayGravel

Clay

Gravel

ClayBedrock

ClayGravelClay

Shale/igneous

P1

P2

P1

P2

P1

P2

P3

P1

P1 P1

P1

P1

P2

P1

P1

P2

P1

240.7

243.2

237.6

245.4

222.0

222.5

224.9

224.6

224.5

224.1

223.8

229.4 233.1

253.2

251.6

271.5

233.8

243.8

255.6253.3

218.5

36005

Namoi

36096

Har crx36186

36187

30129Maules 1

30130

96137Maules

Elfin crxUHA

Fassifern

3617936093 36164

30131


Sands and gravels

Clays

Bedrock: shalessandstones/coal

?

?

??

?

Drawdownfrom August to October

dH = HAug – HOct

(In same well!)

HAug HOct

Maules Creek

2000 m

Horsearm Creek

Mau

les

CreekN

14

Field site at the Namoi River

P

1

3

5

R

218

219

220

221

222

223

9/11

/200

7

16/1

1/20

07

23/1

1/20

07

30/1

1/20

07

7/12

/200

7

14/1

2/20

07

21/1

2/20

07

28/1

2/20

07

Wat

er L

evel

Ele

vati

on

(m

AH

D)

0

2

4

6

8

10

12

14

16

18

20

Pu

mp

Flo

w R

ate

(l/s

)

RiverBH1BH3-1Pump

Evidence for surface and groundwater exchange: Head data

70 m from river screened at 16.5 m.b.s.

20 m from river screened at 12.5 m.b.s.

16

Stable isotopes of surface and groundwater and

17

Stable isotopes of surface and groundwater in the Namoi Valley

Sampling sites

-80

-60

-40

-20

0

20

-12 -10 -8 -6 -4 -2 0 2 4δ18O (‰ )

δ2H

(‰

)

Gunnedah rainfall 1998-2001

Rain, volume w eighted average

Namoi River Gunnedah

Lake Keepit

Namoi River at Maules Creek 2006-2007

Namoi River at Mollee

Maules Creek surface 2006-2007

Mt Kaputar 2007GMWL

LMWL

LEL

2007

2006

Stable isotopes of rain and surface water in the Namoi Valley

Maules Creek surface water samples

18

-80

-60

-40

-20

0

20

-12 -10 -8 -6 -4 -2 0 2 418O (‰ )

2H

(‰

)

Rain, volume w eighted average

Namoi River Gunnedah

Namoi River at Mollee

Namoi River at Maules Creek 2006-2007

Groundw ater 2006-2007

Maules Creek surface 2006-2007GMWL

LMWL

LEL

2007

2006

Stable isotopes of surface and groundwater in the Namoi Valley

Shallow groundwater samples close to the Namoi River

of shallow groundwater (< 30 m) in the Maules Creek catchment

-26.80

-36.50

-26.90

5.10

-37.20

-36.60

-31.40

-38.80-36.70

-33.70

-19.80

-36.80

-35.80

-38.20

-32.70

-18.10

-31.40

-30.10

-40.10

-28.40

-25.1

-26.4-24.8

14.5

14.4

-30.1

Maules Creek

2000 m

d2H

19

MaulesCreek

catchment



Maules Creek

Ho

rsea

rm C

reek

Mid

dle

Cre

ekNam

oi R

iver

Nam

oi River

Irrigation well

Multilevel wells

Groundwater stable isotope study near the Namoi River

20

Natural flow/winter

Observationwells

Irrigation well

Regional

groundwater

flow

~500 m

Irrigation

Observationwells

Deep drainage ?

Deep drainageRegional

groundwater

River water

21

Multilevel groundwater sampler

Depth profiles f

0

5

10

15

20

25

30

35

-8 -6 -4 -218O

m.b

.s.

Bore 6

0

5

10

15

20

25

30

35

-8 -6 -4 -218O

m.b

.s.

Bore 2

In cotton field away from river Near the Namoi River

River water ?

22

-60

-50

-40

-30

-20

-10

-8 -6 -4 -218O (‰ )

2H

(‰

)

Site near the river

Site in cotton field

LMWL

LEL

vs

-7.0

-6.5

-6.0

-5.5

-5.0

0 2 4 6 8 10Days

18 O

(‰

)

-46

-44

-42

-40

-38

-36

-34

-32

-30

2 H (

‰)

d 18O

d 2H

Namoi River Isotopes 13-21 of Feb. 2008

23

Use of heat transport for studying surface water groundwater interactionsSource: USGS Fact Sheet 2004-3010

18.1

13.4

11.5

16.4

16.017.4

11.5

2

21.2

20.820.6

21.9

21.4

21.7

20.1

19.9

20.620.6

21.9

20.4

20.9

21.5

21.6

18.6

20.8

20.9

20.0

21.1

20.7

Maules Creek

2000 m

Heat as a tracerTemp. upper aquifer (<30 m) and surface water August

24

Field example Maules Creek, NSWUsing streambed temperature profiles



Maules Creek

Ho

rsea

rm C

reek

Mid

dle

Cre

ekNam

oi R

iver

Nam

oi River



Maules Creek

Ho

rsea

rm C

reek

Mid

dle

Cre

ekNam

oi R

iver

Nam

oi River

Data requirements

25

Temperature array construction

Gabriel Rau

Field installation

26

Numerical solution to heat flow

0 6 12 18 24Time [hours]

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Te

mp

era

ture

[°C

]

depth z = 0 m

depth z = 0.3 m

A2

Ps

A1

Data collection and processing

27

Some results

-0.6

-0.4

-0.2

0.0

Ve

loci

ty [m

/d]

Exchange Velocities, Probe 1/3 (spacing 0.30m), Beta = 0 mAmplitude Ratio

Phase Shift

Forward Model (Beta = 0 m)

0.0

D

-0.8

-0.6

-0.4

-0.2

Ve

loci

ty [

m/d

]

Exchange Velocities, Probe 1/3 (spacing 0.30 m), Beta = 0.03 mAmplitude Ratio

Phase Shift

Forward Modelling (Beta=0.03 m)

D

-0.6

-0.4

-0.2

0.0

Vel

ocity

[m/d

]

5/9/07 15/9/07 25/9/07 5/10/07 15/10/07 25/10/07Date

Exchange Velocities, Probe 2/4 (spacing 0.3 m), Beta = 0.03 mAmplitude Ratio

Phase Shift

Forward Modelling (Beta = 0.03 m)

E

Effects of dispersion and deviation from the 1-D flow assumption

VAR

VPS

0 0.5 1 1.5 2Simulated Velocity Ratio vh/vv

-1.3

-1.2

-1.1

-1.0

-0.9

Cal

cula

ted

Ve

loci

ty [m

/d]

VAR

VPS

0 0.5 1 1.5 2Simulated Velocity Ratio vh/vv

Spacing = 0.15 m, Alpha = 0.015 m Spacing = 0.6 m, Alpha = 0.06 m

vh / vv = 0, alpha = 0.00 m-2

-1

Dep

th [

m]

0 1 2 3 4 5

vh / vv = 0, alpha = 0.03 m-2

-1

0 1 2 3 4 5

vh / vv = 0, alpha = 0.06 m-2

-1

0 1 2 3 4 5

vh / vv = 2.0, alpha = 0.00 m-2

-1

De

pth

[m]

0 1 2 3 4 5

vh / vv = 2.0, alpha = 0.03 m-2

-1

0 1 2 3 4 5

vh / vv = 2.0, alpha = 0.06 m-2

-1

0 1 2 3 4 5

19 19.2 19.4 19.6 19.8 20 20.2 20.4 20.6 20.8 21Temperature [°C]

28

Conceptual model for surface water groundwater interactions

?

Streambed chemistryand stygofauna sampling

29

Sampling sites

1

2

3

4

1

2

3

4

1

2

3

4

0 100 200 300

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

O2 (uM)

0 100 200 300

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

De

pth

(m)

O2 (uM) 0 100 200 300

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

O2 (uM)0 100 200 300

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

O2 (uM)

Dissolved Oxygen

0 5 10 15 20 25 30

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

NO3- (uM)

0 2 4 6

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

De

pth

(m)

NO3- (uM)

0 5 10 15 20 25 30

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

NO3- (uM)

0 5 10 15 20 25 30

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

NO3- (uM)

Nitrate

0 5 10 15 20 25

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Fe2+ (uM)0 5 10 15 20 25

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Dep

th (m

)

Fe2+ (uM)0 5 10 15 20 25

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Fe2+ (uM)0 5 10 15 20 25

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Fe2+ (uM)

Ferrous Iron

0 5 10 15 20

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Mn2+ (uM)0 5 10 15 20

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

De

pth

(m)

Mn2+ (uM)0 5 10 15 20

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Mn2+ (uM)0 5 10 15 20

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Mn2+ (uM)

Manganese

O2

1234

NO3-

Fe2+

Mn2+

Streambed chemistry

results

30

Redox-processes related to reactive organic matter in the stream

O2 + CH2O → CO2 + H2O

4FeOOH(s) + CH2O + H2O→ 4Fe2+ + HCO3

- + 7OH-

4NO3- + 5CH2O →

2N2 + 4HCO3- + CO2 + 3H2O

Oxygen reduction:

Nitrate reduction:

Iron oxide reduction:

Stygofauna from the region

31

Modeling and dataintegration

Geological surface

modelling

METHODOLOGY

Geological map

SOURCE

GIS

EARTHVISION

DEM

Government CD Datasets (PINNEENA and RAINMAN)

Groundwater, Rain and Stream Data

geological map

Export geologic units

Topography maps of locations

Position point data

Topographic surface

modelling

Boreholeattributes

Convert to point dataset with attributes

Data selection, reinterpretation and validation

Data Coordination

DATABASE

32

EARTHVISION

METHODOLOGY

3D GEOLOGICAL MODELLING

Geological surface

modelling

Topographic surface

modelling

Boreholeattributes

4 ROCK

3 SAND-GRAVEL

2 SILT-LOAM

1 CLAY

0 TOPSOIL

MAULES CREEK BORE LITHOLOGY ANALYSIS

33

3D GEOLOGICAL MODEL

(3D structural model of colluvium, alluvium and rock)

3 sand-gravel2 silt-loam1 clay0 topsoil

3D LITHOLOGY MODEL – MAULES CREEK

PROPERTY MODELS

34

NAMOI RIVER PALEOCHANNEL

Z contour (m)

View various properties in sections

35

Catchment processesand irrigated farming

?

?Bedrock

Clay

Sand & gravelClay

Sand & gravel

?

Conclusions• Groundwater abstraction seems to cause long term

decreasing water levels in the aquifer.• Groundwater abstraction appears to enhance

recharge from rivers and streams.• The location of exchange is largely controlled by

variations in the geology and the location of abstraction.

• Changes in flow regimes from gaining to loosing may have impacts on water quality and in turn on streambed ecology.

• Direction of flow and sources of water can sucessfully be determined by: – Streambed temperature profiles – Hydrogeology – Chemical tracers (stable isotopes)

• In the time to come a big challenge will be to quantify processes on catchment scale.

36

Acknowledgements

• CCC-CRC for project funding.

• Department of Water and Energy (DWE) for letting us sample their monitoring wells and for supplying us with basic data from their archive.

• Mr Gary Johnson, CEO of JaycarElectronics for funding the Gary Johnson Chair at UNSW.

Conduction and convection of heatRate of change Conduction Convection (flow)

T is temperature which varies with time (t) and depth (z),

κε is effective thermal diffusivity,Φ is porosity,vf is vertical fluid velocity,ρf is fluid density,cf is heat capacity of the fluidρ is density of the saturated sediment-fluid

system andc is the heat capacity of the sediment-fluid

system.

37

Numerical solution to heat flowApproach 1: Forward modelling. Procedure:

• calculate temperature variations at a given depth using measured surface temperature and a water flow velocity

• compare to the observed temperature at that depth• change water flow velocity til best fit is obtained

16.0

18.0

20.0

22.0

Tem

pera

ture

[°C

]

Elfin Crossing Forward ModellingProbe 1/2 (spacing 0.15 m)Results: vf = -0.314 m/d, Beta = 0 m, RMSE = 0.198 °C

22 0

A

13/9/07 15/9/07 17/9/07 19/9/07 21/9/07 23/9/07 25/9/07 27/9/07 29/9/07Date

16.0

18.0

20.0

22.0

Tem

pera

ture

[°C

]

Probe 1/5 (spacing 0.60 m)Results: vf = -0.588 m/d, Beta = 0.015, RMSE = 0.192 °C(Legend is representative for plots A, B and C)

Water Temperature

Sediment Temperature

Modelled Temperature

D

Works only for arelatively constant water velocity !!!

15 cm

60 cm

Numerical solution to heat flowApproach 3: 2/3-D numerical modelling of water flow and heat conduction and convection

0 1 2 3 4 5-2

-1

0

Streambed ModelObservation Points

Time

19.0

20.0

21.0

Te

mp

era

ture

[°C

]

0.8

0.9

1.0

1.1

1.2

Ve

loci

ty [

m/d

]

Time19.0

20.0

21.0

Te

mp

era

ture

[°C

]

0.0

1.0

2.0

Ve

loci

ty [

m/d

]

Outflow TemperatureVelocity = 1 m/d

Outflow

Tem

peratureO

utflow =

Inflow

Free USGS software: VS2DHIwww.usgs.gov.us

38

Hydrochemistry – Maules CreekSands and gravels

Clays

Bedrock: sandstones, shales, volcanics and coals

Water table

South-west North-eastNitrate [mg/L]

Maules CreekHorsearm Creek

Namoi River

d)

Alkalinity [meq/L]South-west North-east


Namoi River

b)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Distance, m


DOC [mg C/L]Maules Creek

Horsearm Creek

Namoi River

f)

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

Dep

th b

elo

w s

urfa

ce, m

30131

South-westNorth-east

O2 [mg/L]Maules Creek

Horsearm Creek

Namoi River

c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Distance, m

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

De

pth

belo

w s

urf

ace

, m

Fe2+ [ug/L]South-west North-east


Namoi River

e)

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

Dep

th b

elow

sur

face

, m

Well point heads [m]South-west North-east

Maules Creek

Horsearm Creek

Namoi River

a)

Hydrochemistry – Northern transect

100

120

140

160

180

200

220

240

260

De

pth

be

low

su

rfa

ce, m

West EastEC [uS/cm]

Namoi River

a)

100

120

140

160

180

200

220

240

260

De

pth

be

low

su

rfa

ce, m

West EastO2 [mg/L]

Namoi River

c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Distance, m

100

120

140

160

180

200

220

240

260

De

pth

be

low

su

rfa

ce, m

West EastFe2+ [ug/L]Namoi River

e)

West EastAlkalinity [meq/L]

Namoi River

b)

West East

0.58

Nitrate [mg/L]

Namoi River

d)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000

Distance, m

West EastDOC [mg-C/L]

Namoi River

f)

Sands and gravels

Clays

Bedrock: sandstones, shales, volcanics and coals

Water table

39

Hydrochemicaland

Tracer methods

Winter et al. 1998

Heat

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