3.4.3.2 Potential hydrological impacts


3.4.3.2.1 Groundwater

Outside the modelled open-cut mine pits, floodplain or lowland riverine landscapes that are potentially impacted cover 20 km2 (which is 0.3% of the ‘Floodplain or lowland riverine’ landscape group in the assessment extent) of remnant vegetation and 299 km (1.0%) of streams, which are predominantly not groundwater dependent (Figure 25 and Table 8). Temporary lowland streams in the zone of potential hydrological change include Dogwood and Rocky creeks to the south-west of The Range coal mine that flow into the Condamine and Balonne rivers.

Median additional drawdown is less than 2 m, with the exception of 0.2 km2 of remnant vegetation and 20 km of streams near the open-cut coal mine pits (Table 11), where median additional drawdown in the regional watertable is up to 65 m near New Acland Coal Mine and up to 10.2 m near The Range coal mine. Median baseline drawdown in the zone of potential hydrological change is predominantly greater than 2 m, containing 8 km2 of remnant vegetation and 112 km of streams (Figure 25 and Table 10).

Drawdown under the baseline is greater than due to additional coal resource development for most remnant vegetation and streams in the ‘Floodplain or lowland riverine’ landscape group (Figure 26). This is consistent with their location near the outer edges of the zone of potential hydrological change, where additional drawdown is less.

Figure 25

Figure 25 'Floodplain or lowland riverine (including non-GAB GDEs)' landscape group: location of remnant vegetation or 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. Landscape classes within modelled 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 26

Figure 26 'Floodplain or lowland 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

Colours represent the 5th, 50th and 95th 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. Areas 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 10 ‘Floodplain or lowland riverine (including non-GAB GDEs)’ landscape group: area (km2) or stream network length (km) that exceeds the 5th, 50th and 95th percentile estimates of baseline drawdown in the zone of potential hydrological change


Landscape class

Length or area

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

Floodplain remnant vegetation

Area (km2)

2,086

19.7

14.6

19.4

19.5

5.8

7.5

9.3

0.8

3.0

4.7

Floodplain, near-permanent wetland

Area (km2)

147

0

0

0

0

0

0

0

0

0

0

Floodplain, non-GAB GDE

Area (km2)

2,455

0.3

0.03

0.03

0.03

0.01

0.03

0.03

0

0

0

Floodplain, non-GAB GDE, near-permanent wetland

Area (km2)

61.0

0

0

0

0

0

0

0

0

0

0

Floodplain, non-GAB GDE, temporary wetland

Area (km2)

442

0

0

0

0

0

0

0

0

0

0

Floodplain, temporary wetland

Area (km2)

675

0.1

0.1

0.1

0.1

0.1

0.1

0.1

0

0.1

0.1

Subtotal

Area (km2)

5,866

20.1

14.8

19.6

19.6

5.9

7.6

9.5

0.8

3.0

4.8

Near-permanent, lowland stream

Length (km)

170

0

0

0

0

0

0

0

0

0

0

Temporary, lowland non-GAB GDE stream

Length (km)

268

2.6

0

0

0

0

0

0

0

0

0

Temporary, lowland stream

Length (km)

28,716

296

232

286

287

84.5

112

136

7.8

23.6

47.0

Subtotal

Length (km)

29,154

299

232

286

287

84.5

112

136

7.8

23.6

47.0

aExtent could be 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 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)

Table 11 ‘Floodplain or lowland riverine (including non-GAB GDEs)’ landscape group: area (km2) or stream network length (km) that exceeds the 5th, 50th and 95th percentile estimates of additional drawdown in the zone of potential hydrological change


Landscape class

Length or area

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

Floodplain remnant vegetation

Area (km2)

2,086

19.7

3.5

8.6

19.7

0

0.01

1.3

0

0.01

0.01

Floodplain, near-permanent wetland

Area (km2)

147

0

0

0

0

0

0

0

0

0

0

Floodplain non-GAB GDE

Area (km2)

2,455

0.3

0.03

0.2

0.3

0

0.2

0.2

0

0.2

0.2

Floodplain, non-GAB GDE, near-permanent wetland

Area (km2)

61.0

0

0

0

0

0

0

0

0

0

0

Floodplain, non-GAB GDE, temporary wetland

Area (km2)

442

0

0

0

0

0

0

0

0

0

0

Floodplain, temporary wetland

Area (km2)

675

0.1

0

0

0.1

0

0

0

0

0

0

Subtotal

Area (km2)

5,866

20.1

3.6

8.9

20.1

0

0.2

1.5

0

0.2

0.2

Near-permanent, lowland stream

Length (km)

170

0

0

0

0

0

0

0

0

0

0

Temporary, lowland non-GAB GDE stream

Length (km)

268

2.6

0

1.8

2.6

0

0.6

0.6

0

0.6

0.6

Temporary, lowland stream

Length (km)

28,716

296

80.6

147

296

3.9

19.7

52.6

0.4

4.9

13.1

Subtotal

Length (km)

29,154

299

80.6

149

299

3.9

20.3

53.1

0.4

5.5

13.7

aExtent could be a length or area and excludes modelled open-cut mine 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)

3.4.3.2.2 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