Hydrogeological assessment of two important wetlands (GDEs) in Hodgson's Wetland suite

1. SCHOOL OF EARTH AND ENVIRONMENT
Nathan Senevirathne
Supervisor
Associate Professor Ryan Vogwill
Oct
2013

2. Regional setting of project area
BMNDRC
Study area
The study area is part of Buntine-Marchagee Natural Diversity Recovery Catchment (BMNDRC)
The University of Western Australia

3. Regional setting of project area
Study area sub-catchment
(~ 600 ha = 0.02 % of BMNDRC)
W023
W024
W023
W024
The University of Western Australia

4. Remnant vegetation and landuse
~90%
Wheat Plantation
Lupin Plantation
~4%
Canola Plantation
Re-vegetated in 2013
Salt – tolerant shrubs
Eucalyptus overstory
The University of Western Australia

5. Geology & Topography
•
•
•
•
•
Drilling program carried out in mid 2012
LiDAR data
Geological survey of Western Australia by Baxter & Lipple 1985
The geology, physiography and soils of wheatbelt valleys by Commander et al. 2001
Regolith geology of the Yilgarn Craton, Western Australia: implications for exploration by Anand & Paine 2002
 The entire study area is a low relief region that lies over Archaean
granitic rock of the Yilgarn Craton; ~340 mAHD on WEST and ~290 mAHD
on EAST
 The typical soil structure is comprised of fresh granitic bedrock grading
upwards into saprock and saprolite which are overlain by lacustrine
clays, palaeochannel silts, yellow earthy sands (Balgerbine Soil System)
(Anand & Paine 2002)
 Basement rocks are exposed only at a small area near western margin
and maximum depth is about 35 m
 There is only one dyke appearing just outside of south-west margin
(Geological Survey Western Australia by Baxter & Lipple 1985)
The University of Western Australia

6. Geology & Topography
Soil types, dykes and isolated outcrops of granite in the study area
(Baxter & Lipple 1985)
The University of Western Australia

7. Geology & Topography
The gradient of slope in the study area
The University of Western Australia

8. Geology & Topography
A
B
C
B
A
C
D
D
Digital elevation profiles of study
area using LiDAR elevation data
The University of Western Australia

9. Groundwater monitoring network
The University of Western Australia

10. Methodology Surface water catchment delineation
surface flow that could be generated by
a heavy rainfall
W023
W024
The University of Western Australia

11. Methodology Surface water catchment delineation
New Boundary
618 ha
589 ha
The University of Western Australia

12. Methodology Hydrogeochemistry
 Water samples were collected from monitoring bores and several wetlands on 30th
April 2013. Electrical Conductivity (EC), Oxidation-Reduction Potential (ORP), pH,
and temperature were measured at the field.
 Ion chromatography using Dionex DX500 systems to determine the concentrations
of major cations and anions
Na-Cl type
Na-Cl type
waters
waters
The University of Western Australia

13. Methodology Hydrogeochemistry
Dominance of Cl-, Na+, SO42-, Mg2+ and HCO3- in water samples
Molar Cl/Br ratios vs. Cl- concentrations (mol/L) in water
samples collected from groundwater and wetlands
The University of Western Australia

14. Methodology Hydrogeochemistry
Distribution of Total Dissolved Solids (TDS) in study area
The University of Western Australia

15. Methodology Conceptual model of wetland-scaled water balance
Open water body ET
Rainfall
Surface water in-flow
Superficial in-flow
Bare soil ET
Surface water out-flow
Superficial out-flow
Saprolitic
Aquifer
Saprolitic
Saprolitic
discharge
recharge
Bedrock
The University of Western Australia

16. Methodology Conceptualising groundwater flow
B
A’
B’
A
Transects of hydrogeological profiles marked on study area sub-catchment
The University of Western Australia

17. Methodology Conceptualising groundwater flow
The University of Western Australia

18. Methodology Conceptualising groundwater flow
The University of Western Australia

19. Methodology Conceptualising groundwater flow
Groundwater equipotential lines and flow in shallow aquifer
The University of Western Australia

20. Methodology Conceptualising groundwater flow
Groundwater equipotential lines and flow in the saprolitic aquifer
The University of Western Australia

21. Methodology Evapotranspiration
Open water body Evapotranspiration
0.7
(Marimuthua, Reynoldsa & Salle 2005; Allison 1974;
Tweeda, Leblanca & Cartwright 2009)
(Tweeda, Leblanca & Cartwright 2009)
Where
The University of Western Australia

22. Methodology Evapotranspiration
Estimating bare soil evapotranspiration - Chen (1992)
Monthly bare soil ET with E1 (0.024 of Epan) and E2 (0.4 of Epan)
Epan
Jan
Feb
Mar
Apr
May
396.4 357.7 310.5 191.4 121.1
Jun
72.8
Jul
81.4
Aug
97.2
Sep
Oct
Nov
Dec
131.2 209.0 281.2 379.4
Mean number
of days of rain
≥1mm
2.0
1.8
2.2
1.5
5.0
6.2
7.5
6.4
5.1
2.6
2.0
1.7
E1 (mm/month)
E2 (mm/month)
8.3
20.5
7.5
18.4
6.4
17.6
4.1
7.7
2.0
15.6
1.0
12.0
1.0
15.7
1.4
16.1
2.1
17.8
4.2
14.0
5.8
15.0
8.1
16.6
mid Feb – beginning June
(4 months)
The University of Western Australia

23. Methodology Surface water run-off
(Groen and Savenije 2006)
•
Assumed that surface run-off within the immediate vicinity of W023 and W024
Jan
Surface run-off from
area of 1000 m 2
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
6.8
5.1
7.3
4.4
15.4
17.1
22.1
18.4
14.2
7.4
5.3
5.5
129.1
Jan
Monthly Interception
(Im) - mm
Feb
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Annual
4.5
1.2
4.0
1.3
5.3
3.5
6.0
4.5
3.0
1.7
0.9
2.6
38.6
(m3 )
The University of Western Australia

24. Methodology Surface water run-off
Possible flow patterns of surface water in-flow (generated using ArcGIS 10.1)
The University of Western Australia

25. Methodology Surface water run-off
Elevation profiles across W023 and W024
A
A
B
D
H
W023
D
C
C
F
E
W024
G
G
B
H
E
F
The University of Western Australia

26. Methodology Surface water run-off
Estimation of surface area of water body
W etland
Highes t
s urafce Area
(m 2 )
Highes t water
lev el (m)
Annual minimum
water lev el (m)
Surface area at
minimum depth
(m 2 )
Av erage s urface
area (m 2 )
W 023
W 024
7623.5
10584.0
1.35
0.64
0.70
0.00
1475.9
0.0
4549.7
5292.0
The University of Western Australia

27. Results
Water and Chloride balance of W023
Volume
(m 3 /y ear)
Cl concentration
(mg/L)
Cl - Mas s
(kg/y ear)
2188.7
1980.0
8.0
1036.0
17.5
2051.3
Section 3.1 and 3.12
Section 3.9 and 3.12
Vertical groundwater inflow (GW in )
1048.9
1036.0
1086.7
Section 3.9 and 3.12
Surface water inflow (SW in )
4061.1
8.0
32.5
INPUT
Precipitation (P)
Horiz ontal groundwater inflow (GW in )
9278.7
OUTPUT
Horiz ontal groundwater outflow (GW out )
Open water body ev apotrans piration (ET)
Comments
Section 3.11 and 3.12
3188.0
1825.0
9370.2
Total input
2628.0
Section 3.9 and 3.12
Section 3.10.1 and 3.12
2628.0
1440.0
7930.2
Percentage
of error
Total output
3
-91.5
m /y ear
-12.0
mm/y ear
560.0 kg/y ear Balance
Water and Chloride balance of W023 for a period of 12 months (from Sep 2012 to Sep 2013)
The University of Western Australia

28. Results
Water and Chloride balance of W024
Volume
(m 3 /y ear)
INPUT
Precipitation (P)
Horiz ontal groundwater inflow (GW in )
Surface water inflow (SW in )
Cl concentration
(mg/L)
Cl - Mas s
(kg/y ear)
3116.2
1055.9
8.0
1097.0
24.9
1158.3
2923.4
8.0
23.4
7095.5
OUTPUT
Horiz ontal groundwater outflow (GW out )
Open water body ev apotrans piration (ET)
Bare s oil ev aporation (ET)
Section 3.1 and 3.12
Section 3.9 and 3.12
Section 3.11 and 3.12
1206.7
1921.0
Total input
1517.1
Section 3.9 and 3.12
Section 3.10.1 and 3.12
1517.1
789.8
5062.9
981.2
6833.8
261.7
34.3
Comments
Total output
3
m /y ear
mm/y ear
-310.5 kg/y ear Balance
Water and Chloride balance of W024 for a period of 12 months (from Sep 2012 to Sep 2013)
The University of Western Australia

29. Results
Discussion
Water quality
W 023
3.8 to 7.43
W 024
0.18 to 7.92
pH
7.49 to 9.08
6.95 to 8.65
Redox potential (eh mV)
EC (mS/cm)
- 97.5 to 205
- 65 to 201
Cl- (mg/L)
1825
1921
TDS (mg/L)
3448
4826
Water balance components of W023
Volume
(m 3 /y ear)
24%
21%
INPUT
Precipitation (P)
Horiz ontal groundwater inflow (GW in )
Cl concentration
(mg/L)
Cl - Mas s
(kg/y ear)
2188.7
1980.0
8.0
1036.0
17.5
2051.3
1%
64%
11%
Vertical groundwater inflow (GW in )
1048.9
1036.0
1086.7
34%
44%
Surface water inflow (SW in )
4061.1
8.0
32.5
1%
9278.7
15%
85%
OUTPUT
Horiz ontal groundwater outflow (GW out )
Open water body ev apotrans piration (ET)
3188.0
1440.0
7930.2
1825.0
9370.2
2628.0
2628.0
3
-91.5
m /y ear
-12.0
mm/y ear
560.0 kg/y ear
The University of Western Australia

30. The University of Western Australia

31. The University of Western Australia

32. Results
Discussion
Water balance components of W0234
Volume
(m 3 /y ear)
44%
15%
41%
INPUT
Precipitation (P)
Horiz ontal groundwater inflow (GW in )
Surface water inflow (SW in )
Cl concentration
(mg/L)
Cl - Mas s
(kg/y ear)
3116.2
1055.9
8.0
1097.0
24.9
1158.3
2%
96%
2923.4
8.0
23.4
2%
7095.5
12%
74%
14%
OUTPUT
Horiz ontal groundwater outflow (GW out )
Open water body ev apotrans piration (ET)
Bare s oil ev aporation (ET)
789.8
5062.9
981.2
6833.8
261.7
34.3
Uncertainty
1206.7
1921.0
1517.1
100%
1517.1
3
m /y ear
mm/y ear
-310.5 kg/y ear
Component
Error %
Reference
Lake-to-Pan coeff
30%
(Tweeda, Leblanca & Cartwright 2009)
Surface area (Surface water, ET)
Winter (1981), TBRG - (Australian Bureau of Meteorology 2011)
Precipitation
16% - 26%
Winter (1981), TBRG - (Australian Bureau of Meteorology 2011)
Groundwater (Hydraulic conductivity)
40%
slug tests in Nabappie subcatchment – Variability in Average
Groundwater (Capture zone – ± 0.5)
10%
Statistically
Cl- content in surface water
Nabappie catchment 500 to 5000 mg/L Bourke (2011)
The University of Western Australia

33. Results
Conclusion
W023 & W024
•
•
•
•
•
Flow-through wetlands
Direct contact with the water table of the surficial aquifer
Can be assumed that both of the wetlands are underlain by a silcrete hardpan
Hydrogeochemically different
Majority of inputs being sourced from groundwater and surface water runoff
components.
• Considerable attention should be given to the surface water runoff component
because it may carry a significant amount of solutes to wetland W023 (Winter
1981).
The University of Western Australia

34. Results
Conclusion
W023
concept is supported by the occurrence of
mature perennial vegetation in the northern
half of wetland W023
The University of Western Australia

35. Results
Conclusion
W024
concept is supported by the occurrence of
mature perennial vegetation in the northwestern part of wetland W024
The University of Western Australia

36. Results
Conclusion
Iso- annual average total dissolved solids (TDS mg/L) curves along AA’
The University of Western Australia

37. Questions
The University of Western Australia