3.4.4.2 Potential hydrological impacts


3.4.4.2.1 Groundwater

Potentially impacted GAB GDEs cover 76 km2 (which is 4.4% of the landscape group in the assessment extent) of remnant vegetation and 319 km (4.1%) of streams in the zone of potential hydrological change (outside of modelled open-cut mine pits) (Figure 28 and Table 8). Most of the remnant vegetation (75 km2) and watercourses (254 km) that access GAB aquifers in the zone of potential hydrological change are to the north-east of The Range coal mine in an area of Hutton Sandstone aquifer outcrop.

None of the 153 GAB springs in the assessment extent are within 50 km of where there is at least a 5% chance of exceeding 0.2 m drawdown due to additional coal resource development predicted in the source aquifer identified for each spring (Office of Groundwater Impact Assessment, Dataset 5; Bioregional Assessment Programme, Dataset 6).

The median (50th percentile) estimate of greater than 0.2 m drawdown due to additional coal resource development is smaller and includes less than 1 km2 of remnant vegetation and 3 km of streams in this landscape group (Table 14). Figure 28 and Figure 29 show that most of the streams classified as ‘GAB GDEs’ in the north-eastern part of the zone of potential hydrological change have a median drawdown due to additional coal resource development of less than 0.2 m. Median baseline drawdown in the zone of potential hydrological change is predominantly less than 2 m, containing 3 km2 of remnant vegetation and 5 km of stream network (Table 13).

Figure 28

Figure 28 'GAB GDEs (including riverine, springs, floodplain or non-floodplain)' 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 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 29

Figure 29 'GAB GDEs (including riverine, springs, floodplain or non-floodplain)' 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 pits are not included in this analysis. GAB = Great Artesian Basin, GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 7)

Table 13 ‘GAB GDEs (riverine, springs, floodplain or non-floodplain)’ 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

Floodplain, GAB GDE

Area (km2)

290

0.8

0

0.8

0.8

0

0

0

0

0

0

Floodplain, GAB GDE, near-permanent wetland

Area (km2)

0.3

0

0

0

0

0

0

0

0

0

0

Floodplain, GAB GDE, temporary wetland

Area (km2)

8.7

0

0

0

0

0

0

0

0

0

0

Non-floodplain, GAB GDE

Area (km2)

1446

75.3

5.1

75.3

75.3

3.4

3.4

3.4

0.0

0.0

0.5

Non-floodplain, GAB GDE, near-permanent wetland

Area (km2)

0.0

0

0

0

0

0

0

0

0

0

0

Non-floodplain, GAB GDE, temporary wetland

Area (km2)

1.6

0

0

0

0

0

0

0

0

0

0

Subtotal

Area (km2)

1746

76.1

5.1

76.1

76.1

3.4

3.4

3.4

0.0

0.0

0.5

Temporary, lowland GAB GDE stream

Length (km)

3585

64.7

6.4

58.8

62.1

3.0

3.0

3.0

0

0

0.8

Temporary, upland GAB GDE stream

Length (km)

4183

254

17.6

247

251

2.5

2.5

3.2

0

0

0.6

Subtotal

Length (km)

7768

319

24.0

305

313

5.5

5.5

6.2

0

0

1.4

GAB springs

Number

153

0

0

0

0

0

0

0

0

0

0

Subtotal

Number

153

0

0

0

0

0

0

0

0

0

0

aExtent could be 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 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 14 ‘GAB GDEs (riverine, springs, floodplain or non-floodplain)’ landscape group area (km2), stream network length (km) and number of springs (number) that exceed the 5th, 50th and 95th percentile estimates of drawdown due to additional coal resource development 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 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

Floodplain GAB GDE

Area (km2)

290

0.8

0

0

0.8

0

0

0

0

0

0

Floodplain GAB GDE, near-permanent wetland

Area (km2)

0.3

0

0

0

0

0

0

0

0

0

0

Floodplain GAB GDE, temporary wetland

Area (km2)

8.7

0

0

0

0

0

0

0

0

0

0

Non-floodplain GAB GDE

Area (km2)

1446

75.3

0

0.1

75.3

0

0

0

0

0

0

Non-floodplain GAB GDE, near-permanent wetland

Area (km2)

0.0

0

0

0

0

0

0

0

0

0

0

Non-floodplain GAB GDE, temporary wetland

Area (km2)

1.6

0

0

0

0

0

0

0

0

0

0

Subtotal

Area (km2)

1746

76.1

0

0.1

76.1

0

0

0

0

0

0

Temporary lowland GAB GDE stream

Length (km)

3585

64.7

0

0.7

64.7

0

0

1.5

0

0

1.5

Temporary upland GAB GDE stream

Length (km)

4183

254

0

2.0

254

0

0

0.8

0

0

0.8

Subtotal

Length (km)

7768

319

0

2.6

319

0

0

2.3

0

0

2.3

GAB springs

Number

153

0

0

0

0

0

0

0

0

0

0

Subtotal

Number

153

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.

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)

3.4.4.2.2 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