Toolibin Lake 2010, combining

hydrogeology, remote sensing and

plant ecophysiology to explain the

response to management

interventions. Dr Ryan Vogwill1, 2, Dr Paul Drake1, Blaire Coleman1

and Saskia Noorduijn1, 2

1WA Department of Environment and Conservation, 2University of Western

Australia

Special thanks to; Rachel Taplin, Ken Wallace, Jennifer Higbid,

Katherine Zdunic, Jim Lane, Lance Mudgway, Peter Lacey and Ray

McKnight.

Outline

Altered hydrology (salinity) impacts

Location and Toolibin Lake biological values

Toolibin Lake deep hydrogeology

Timeline of impacts, recovery actions and 1994

management goals

Response to recovery actions (vegetation and

hydrology)

Preliminary outcomes of a multidisciplinary investigation

Soil hydraulics and shallow hydrogeology

Plant ecophysiology

Coupled unsaturated zone/saturated zone modelling

New criteria

Conclusions

Altered Hydrology Impacts

Toolibin Lake

Conservation

Values

October 1978

Photo courtesy of Jim Lane

Ramsar listed wetland of international importance

for water birds (24 sp. breeding, 41 sp. present)

Endangered freckled duck breeding area

Last ephemeral wetland with an “intact”

vegetated lake floor in the WA wheatbelt.

Listed as a Threatened Ecological Community

(TEC) under the EPBC Act 1999.

Natural Diversity Recovery Catchment

Toolibin Hydrogeology

George R, Dogramaci S, Wyland J and Lacey P., 2005, Water engineering at Lake Toolibin,

Western Australia, Australian Journal of Water Resources, Vol 9, No.2.

Altered Hydrology Threat – History and Recovery Actions

1970’s – First tree deaths on the west side of the lake1987 – NARWRC report, Status and Future of Toolibin Lake released1994 – Toolibin Recovery Plan released “Fortress Toolibin”1996 – Surface water management and diversion gates completed1997 – Groundwater pumping begins

Lower images courtesy of Katherine Zdunik

Vegetation Targets

No further deterioration is observed in the health of

the vegetation of the lake or the reserves

Successful tree and shrub regeneration in the lake

and reserves is established in all vegetation

associations

Hydrological Targets

More than 80% of the lake bed with greater than 1.5 m

depth to groundwater in spring (Sept-Oct) when the

lake is not full

The maximum TDS of the lake when full is 1000 mg/l

1994 Recovery Plan - Management Goals

Toolibin Lake – Benefit of InterventionGroundwater

All

pu

mp

s

wo

rkin

g

So

me

pu

mp

s d

ow

n

Mo

st

pu

mp

s

do

wn

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

September 1997

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

September 1998

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

September 1999

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

October 2000

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

September 2001

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

October 2002

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

October 2003

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

September 2004

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

October 2005

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

October 2006

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

October 2007

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

September 2008

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

556000 556500 557000 557500

6356500

6357000

6357500

6358000

6358500

TL17

TL19

TL20

TL23

TL24

TL25

TL26TL27

TL28TL29TL30

TL31

TL32

TL33

TL34

TL36

TL20A

T1/1T1/2

T2/1T2/2

T3/1T3/2

T4/1T4/2

TL18

TL35TL35A

TL01

TL04

P1

P2

P3

P4

P7

P9

P10

P11

P15

P13

P14

September 2009

Pumping Bore

Observation Bore

Depth to Groundwater less than 1.5m

Groundwater

Goals

Performance?

Benefit of intervention

Vegetation change and surface soil moisture

1998 2006

low

water

content

high

water

content

Vegetation Change 2000-2009

Blue - recovery

Red - decline

Green - fluctuating

0

25

50

75

100

125

150

175

200

1998 2000 2002 2004 2006 2008 2010

Nu

mb

er

of

trees

Plot 34

Casuarina obesa

0

200

400

600

800

1000

1200

1996 1998 2000 2002 2004 2006 2008 2010

Nu

mb

er

of

trees

Plot 27

Casuarina obesa

0

20

40

60

80

100

120

140

1996 1998 2000 2002 2004 2006 2008 2010

Nu

mb

er

of

trees

SAP 1

Casuarina obesa Melaleuca strobophylla

0

2

4

6

8

10

12

14

16

18

20

1975 1980 1985 1990 1995 2000 2005 2010

Nu

mb

er

of

trees

Plot 4

Casuarina obesa Melaleuca strobophylla

Vegmachine

Vegetation Change 2000-2009

Blue - recovery

Red - decline

Green - fluctuating

Vegetation Change – Success and failure

Vegetation plots compliments Jen Higbid

Vegmachine plot compliments

Katherine Zdunic

25 years

14 years14 years

12 years

s

ss

s

s

M

M

M

CC

C

Piezometer

Casuarina obesa

Melaleuca strobophylla

Sensor hole

Sap flowmonitoring

20 m

Biorisk Project – Future Farm Industries CRC

556100 556200 556300 556400 556500 556600 556700 556800 556900 557000 557100 557200 557300 557400 557500

320

322

324

320

322

324

6356600 6356800 6357000 6357200 6357400 6357600 6357800 6358000 6358200 6358400

320

322

324

320

322

324

0 400

800

1200

1600

2000

2400

2800

3200

3600

4000

4400

NS-4

EW

-12

EW

-11

EW

-10

EW

-9EW

-8

EW

-7

P3-

1NS-6

NS-5

NS-4

NS-3

NS-2 P

1-1

NW

-14

NS-1

Soil SalinityS N

W E

mA

HD

mA

HD

0 25 45dS/m

Casuarina - shallow rooted and

adapted to less water (can apply a

greater suction) root zone has

experienced some flushing.

Melaleuca - deeper rooted and adapted

to more water (less suction) root zone

has not experienced flushing.

Ecophysiology – Toolibin LakeCasuarina obesa and Melaleuca strobophylla

Soil SalinitySoil Moisture - Matric Potential

Context

Typical temperate zone plants wilting point

1.5 MPa

Arid zone plants wilting point 2-5 Mpa

(Sauer et al, 1983)

Indirect determination of rooting depth and permanent wilting point

R.H. Sauer, M.L. Warner and W.T. Hinds, 1983, Ecological

Modelling, Volume 21, Issues 1-2, January 1984, Pages 109-124

0 15 35dS/m

Soil Moisture Profile (Plot 2)

21/3/10 23/3/10 25/3/1022/3/10 24/3/10 26/3/10

0

0.4

0.8

1.2

1.6

2

Rainfall (m

m)

0

10

20

30

40

50

Soil M

oisture (%

vol)

0

10

20

30

40

EC

(dS

/m

)

0.2m

0.8m

1.6m

3m

Rapid response near surface (macropores?)

Delayed with depth (matrix flow?)

EC response to soil

moisture is delayed

with depth

Some flushing of soil

profile evident

0

5 days

Groundwater Levels (Plot 2)

Groundwater responds slowly (matrix flow)

45 days

What is required to achieve 1994 goals?

Downward flushing of salts in the top 4m of the profile

is required to facilitate vegetation regeneration in both

species.

Soil salinities of less than 5 dS/m are required for high

levels of recovery

Top 1.5m required for the Casuarina obesa

New individuals for both species may be able to

tolerate as little as 1.0 m but the Casuarina will

likely out compete the Melaleuca

Top 3-4m required for Melaleuca strobophylla

Long term (20 years) survival is possible between 15

and 20 dS/m for both species

Rainfall or lake filling, which is better for soil flushing?

Newest evidence of further root zone salinisation under all various climate change

scenarios – 100 years.

Climate_chagne_wetting_

100 yrs

-1000

-800

-600

-400

-200

0

0.0 0.5 1.0 1.5 2.0

Conc [mmol/c m3]

Climate_change_business

as usual_100yrs

-1000

-800

-600

-400

-200

0

0 0.5 1 1.5 2

Conc [mmol/c m3]

-1000

-800

-600

-400

-200

0

0 0.5 1 1.5 2

Conc [mmol/c m3]

Climate_change_drying_100yrsStationary climate

Climate drying Climate wetting

Hydrus 1D modelling

Rainfall alone wont flush the unsaturated

zone. Any salt flushed is reconcentrated

again rapidly by capillary effects and

transpiration

Filling events with deep groundwater can

flush the top 4m in as little as ~ 300 days

However given the possible depth to

groundwater, the relationship between filling

event magnitude (lake level) and depth to

groundwater is crucial for management.

0

10

20

30

40

50

60

0 0.5 1 1.5 2

Surface pressure head (m)

Tim

e (d

ays)

.

<4 m

4 m

5 m

6 m

7 m

8 m

Depth to

groundwater

-1000

-800

-600

-400

-200

0

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

Conc [mmol/c m3]

Profile Information: Concentration

-1000

-800

-600

-400

-200

0

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1

Conc [mmol/c m3]

-1000

-800

-600

-400

-200

0

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

Conc [mmol/cm3]

T0

T1

T2

T3

T4

T5

T6

T7

T8

T9

T10

T11

T12

T13

T14

T15

T16

T17

T18

T19

T20

Profile Information: Concentration

-1000

-800

-600

-400

-200

0

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Conc [mmol/c m3]

-1000

-800

-600

-400

-200

0

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Conc [mmol/c m3]

Lake filling under free drainageRelationship between water table depth

Lake level and time

Soil flushing by rainfall

Time step 20 days

Images courtesy of Rachel Taplin

Time step 5 years

Early intervention by the recovery team in the 1990’s has been

crucial for Toolibin Lake protection

Preliminary hydrological targets have stabilsed the vegetation

condition but are insufficient to achieve the 1994 Recovery Plan

goals

To achieve recovery goals a much greater level of flushing is

required than can be achieved through rainfall alone, even with a

return to higher rainfall (unlikely)

However existing groundwater criteria will help Casuarina but not

Melaleuca

Inflow events need to be carefully managed in combination with

groundwater levels or they could actually make the situation

worse. An artificial discharge system is crucial for this

A high resolution multidisciplinary approach has been required to

understand the response of the system to active management

and for proposing new hydrological targets to meet recovery

goals

The next iteration of the Recovery Plan is underway

Conclusions

Thank you for listening any questions?

Climate – Long term trend

Wickepin (010654) Rainfall. Anuual, Winter and Summer Totals

0

100

200

300

400

500

600

700

1900 1920 1940 1960 1980 2000 2020

Year

Ra

infa

ll(m

m)

Annual

Winter

Summer

20 per. Mov. Avg. (Winter)

20 per. Mov. Avg. (Annual)

20 per. Mov. Avg. (Summer)

Event Volumes

0

500

1000

1500

2000

2500

3000

Ju

l-8

1

Ju

l-8

2

Ju

l-8

3

Ju

l-8

4

Ju

l-8

5

Ju

l-8

6

Ju

l-8

7

Ju

l-8

8

Ju

l-8

9

Ju

l-9

0

Ju

l-9

1

Ju

l-9

2

Ju

l-9

3

Ju

l-9

4

Ju

l-9

5

Ju

l-9

6

Ju

l-9

7

Ju

l-9

8

Ju

l-9

9

Ju

l-0

0

Ju

l-0

1

Ju

l-0

2

Ju

l-0

3

Ju

l-0

4

Ju

l-0

5

Ju

l-0

6

Ju

l-0

7

Ju

l-0

8

Vo

lum

e (

ML

)

0

500

1000

1500

2000

2500

3000

Sa

lt L

oa

d (

t)

Total Volume (ML)

Divertable Volume (ML)

Salt Load of Divertable Volume (t)