3.4.5.2 Potential hydrological impacts


3.4.5.2.1 Groundwater

Outside of the modelled open-cut mine pits, non-floodplain or upland riverine landscapes that are potentially impacted cover 12 km2 (which is 0.4% of the landscape group in the assessment extent) of remnant vegetation and 477 km (2.0%) of streams, which are predominantly not groundwater dependent (Figure 31 and Table 8). Most of the remnant vegetation in the zone (11 km2) is dependent on local groundwater flow systems in the alluvium or Main Range Volcanics aquifers or is associated with non-floodplain wetlands. Most streams in the zone are not groundwater dependent (469 km) and so are unlikely to be affected by groundwater drawdown. None of the ‘Non-GAB springs’ associated with the Main Range Volcanics basalt aquifers are contained within the zone of potential hydrological change.

The median (50th percentile) estimate of exceeding 0.2 m drawdown due to additional coal resource development includes 5 km2 of remnant vegetation and 256 km of stream network (Table 17). Median drawdown due to additional coal resource development is less than 2 m, with the exception of 1 km2 of remnant vegetation adjacent to the modelled open-cut mine pits (Figure 31).

Drawdown under the baseline is less than 2 m for most remnant vegetation and streams in this landscape group (Figure 32). Median baseline drawdown in excess of 2 m covers 3 km2 of remnant vegetation and 182 km of stream network in this landscape group (Table 16.

Figure 31

Figure 31 'Non-floodplain or upland riverine (including non-GAB GDEs)' landscape group: location of remnant vegetation and stream network contained within the zone of potential hydrological change in the Maranoa-Balonne-Condamine subregion

Median is the 50th percentile. Baseline drawdown is the maximum difference in drawdown (dmax) under the baseline relative to no coal resource development. Additional drawdown is the maximum difference in drawdown (dmax) between the coal resource development pathway (CRDP) and baseline, due to additional coal resource development. The mine pits in the CRDP are the sum of those in the baseline and the additional coal resource development (ACRD). Landscape classes within modelled open-cut mine pits are not included in this analysis.

ACRD = additional coal resource development, CSG = coal seam gas, GAB = Great Artesian Basin, GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2, Dataset 3, Dataset 4, Dataset 8, Dataset 9)

Figure 32

Figure 32 'Non-floodplain or upland riverine (including non-GAB GDEs)' landscape group: the top two rows show area (km2) or stream length (km) within the zone that exceeds the 5th, 50th and 95th percentile estimates of baseline drawdown and additional drawdown, and the bottom row shows baseline drawdown (m) compared to additional drawdown (m) in each assessment unit

Baseline drawdown is the maximum difference in drawdown (dmax) under the baseline relative to no coal resource development. Additional drawdown is the maximum difference in drawdown (dmax) between the coal resource development pathway (CRDP) and baseline, due to additional coal resource development. Landscape classes within modelled open-cut mine pits are not included in this analysis. GAB = Great Artesian Basin, GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 7)

Table 16 ‘Non-floodplain or upland riverine (including non-GAB GDEs)’ landscape group: area (km2), stream network length (km) and number of springs (number) that exceed the 5th, 50th and 95th percentile estimates of baseline drawdown in the zone of potential hydrological change


Landscape class

Length, area or number

Extent in assessment extent

Extent in zone of potential hydrological change (excluding modelled open-cut mine pits)

Extenta with baseline drawdown ≥0.2 m

Extenta with baseline drawdown ≥2 m

Extenta with baseline drawdown ≥5 m

5th

50th

95th

5th

50th

95th

5th

50th

95th

Non-floodplain, non-GAB GDE

Area (km2)

2,551

11.1

6.0

6.6

6.7

2.4

2.7

5.1

0

0

0

Non-floodplain, non-GAB GDE, near-permanent wetland

Area (km2)

2.9

0

0

0

0

0

0

0

0

0

0

Non-floodplain, non-GAB GDE, temporary wetland

Area (km2)

32.8

0

0

0

0

0

0

0

0

0

0

Non-floodplain, near-permanent wetland

Area (km2)

46.6

0.5

0.3

0.4

0.4

0.1

0.2

0.2

0

0

0.04

Non-floodplain, temporary wetland

Area (km2)

195

0.9

0.4

0.9

0.9

0.2

0.2

0.4

0

0

0.01

Subtotal

Area (km2)

2,829

12.5

6.7

7.9

8.0

2.6

3.2

5.6

0

0

0.1

Near-permanent, upland stream

Length (km)

159

0

0

0

0

0

0

0

0

0

0

Temporary, upland non-GAB GDE stream

Length (km)

2,119

7.7

0

0

0

0

0

0

0

0

0

Temporary, upland stream

Length (km)

21,757

469

346

452

453

124

182

221

5.6

22.1

54.9

Subtotal

Length (km)

24,035

477

346

452

453

124

182

221

5.6

22.1

54.9

Non-GAB springs

Number

24

0

0

0

0

0

0

0

0

0

0

Subtotal

Number

24

0

0

0

0

0

0

0

0

0

0

aExtent could be a number, length or area and excludes modelled open-cut mine pits.

Baseline drawdown is the maximum difference in drawdown (dmax) under the baseline relative to no coal resource development. Landscape classes within modelled open-cut pits are not included in this analysis. Due to rounding, some totals may not correspond with the sum of the separate numbers.

GAB = Great Artesian Basin, GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 7)

Table 17 'Non-floodplain or upland riverine (including non-GAB GDEs)' landscape group: area (km2), stream network length (km) and number of springs (number) that exceed the 5th, 50th and 95th percentile estimates of additional drawdown in the zone of potential hydrological change


Landscape class

Length, area or number

Extent in assessment extent

Extent in zone of potential hydrological change (excluding modelled mine open-cut pits)

Extenta with additional drawdown ≥0.2 m

Extenta with additional drawdown ≥2 m

Extenta with additional drawdown ≥5 m

5th

50th

95th

5th

50th

95th

5th

50th

95th

Non-floodplain non-GAB GDE

Area (km2)

2,551

11.1

4.0

4.5

11.1

0.3

0.9

1.7

0.0

0.3

0.8

Non-floodplain non-GAB GDE, near-permanent wetland

Area (km2)

2.9

0

0

0

0

0

0

0

0

0

0

Non-floodplain non-GAB GDE, temporary wetland

Area (km2)

32.8

0

0

0

0

0

0

0

0

0

0

Non-floodplain, near-permanent wetland

Area (km2)

46.6

0.5

0.3

0.4

0.5

0

0.1

0.2

0

0.1

0.1

Non-floodplain, temporary wetland

Area (km2)

195

0.9

0.3

0.3

0.9

0

0.1

0.2

0

0

0.1

Subtotal

Area (km2)

2,829

12.5

4.6

5.3

12.5

0.3

1.1

2.1

0

0.4

1.0

Near-permanent upland stream

Length (km)

159

0

0

0

0

0

0

0

0

0

0

Temporary upland non-GAB GDE stream

Length (km)

2,119

7.7

0

4.8

7.7

0

3.2

3.2

0

3.2

3.2

Temporary upland stream

Length (km)

21,757

469

154

251

469

5.1

33.6

78.2

1.1

7.1

20.9

Subtotal

Length (km)

24,035

477

154

256

477

5.1

36.8

81.4

1.1

10.3

24.2

Non-GAB springs

Number

24

0

0

0

0

0

0

0

0

0

0

Subtotal

Number

24

0

0

0

0

0

0

0

0

0

0

aExtent could be a number, length or area and excludes modelled open-cut pits.

Additional drawdown is the maximum difference in drawdown (dmax) between the coal resource development pathway (CRDP) and baseline, due to additional coal resource development. Landscape classes within modelled open-cut mine pits are not included in this analysis. Due to rounding, some totals may not correspond with the sum of the separate numbers.

GAB = Great Artesian Basin, GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 7)

3.4.5.2.2 Surface water

No surface water numerical modelling was undertaken for the Maranoa-Balonne-Condamine subregion. Some potential hydrological changes may, however, be specified conceptually based on scientific logic as described in Section 3.3.

Last updated:
4 January 2019
Thumbnail of the Maranoa-Baloone-Condamine subregion

Product Finalisation date

2017
PRODUCT CONTENTS