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What are the potential impacts of additional coal resource development on the landscape?


The impact and risk analysis (Box 8) investigated how hydrological changes due to additional coal resource development may affect landscape-scale ecosystems, such as floodplains, irrigated agriculture or remnant vegetation. These ecosystems were classified into landscape classes and landscape groups (Box 7).

The landscape groups in the subregion are:

  • ‘Floodplain or lowland riverine’: fringing riverine, wetland and floodplain communities, including groundwater-dependent ecosystems (GDEs) that do not access Great Artesian Basin (GAB) aquifers. Fringing riverine and wetland communities depend on groundwater within natural watertable fluctuations (less than 2 m); floodplain communities are more tolerant of watertable fluctuations (less than 5 m); and lowland ecosystems rely on surface water and incident rainfall (they are less dependent on groundwater)
  • ‘GAB GDEs’: GDEs that are hydrologically connected to GAB aquifers including streams, springs, areas of floodplain or wetland habitat, and sandstone outcrop areas. These ecosystems typically contain endemic species or plants that are unique to the subregion, and depend on watertable levels within natural seasonal and climatic variations (less than 2 m). Groundwater discharge to streams from GAB aquifers also supports the maintenance of flow regimes and channel habitat
  • ‘Non-floodplain or upland riverine’: non-GAB GDEs that access perched, or isolated, watertables, such as inland sand ridges and basalt aquifers, such as the Main Range Volcanics. These communities depend on watertable levels within natural fluctuations (less than 2 m). Many of the upland streams flow through human-modified landscapes and rely on localised runoff from rainfall; they are less dependent on groundwater
  • ‘Human-modified’: ecosystems that rely heavily on groundwater and surface water extracted from nearby aquifers and streams, such as intensive uses and irrigated agriculture and plantations. Dryland cropping and grazing rely on incident rainfall and localised runoff and were not considered to be water dependent for this assessment
  • ‘Dryland remnant vegetation’: this ecosystem depends on incident rainfall and localised runoff. As such, it was not considered to be water dependent for this assessment.

Results are reported at the scale of landscape group in this synthesis, but further detail at the scale of landscape class is reported in the impact and risk analysis (Holland et al., 2017).

Box 7 Understanding the landscape

The natural and human-modified ecosystems in the subregion were classified into 34 landscape classes (Figure 17 in Holland et al. (2016)) to enable a systematic and comprehensive analysis of potential impacts on, and risks to, the water-dependent assets nominated by the community. These landscape classes were aggregated into five landscape groups (Figure 10), based on their likely response to hydrological changes. The landscape classification was based on the geology, geomorphology, hydrogeology, land use and ecology.


Figure 10

Figure 10 Landscape groups within the zone of potential hydrological change in the vicinity of New Acland Coal Mine Stage 3 and The Range proposed coal mine

CSG = coal seam gas, GAB = Great Artesian Basin, GDE = groundwater-dependent ecosystem. The mine pits in the coal resource development pathway are the sum of those in the baseline and the additional coal resource development (ACRD).

Data: Bioregional Assessment Programme (Dataset 14, Dataset 15)

Box 8 Analysing impact and risk

Potential impacts to water-dependent landscapes and assets were assessed by overlaying their location on the zone of potential hydrological change (Box 5) to identify the hydrological changes that a particular asset or ecosystem might experience.

  • Outside this zone, landscapes and assets are very unlikely to be impacted by hydrological changes due to additional coal resource development.
  • Inside this zone, landscapes and assets are potentially impacted.

Within the zone, not all water-dependent landscapes or assets will be affected, as this depends on their reliance on groundwater or surface water. Hydrological changes due to additional coal resource development may be large, but within the range of natural seasonal and climatic variability, and thus may not affect water-dependent landscapes or assets. Alternatively, small changes may affect sensitive ecosystems that have a strong reliance on groundwater or surface water. See ‘Building on this assessment’ for how to gain more detailed information on the sensitivity of landscapes and assets to hydrological change. For ecological assets, the assessment considered the potential impact to the habitat of species, not potential impacts to the species themselves.

Box 9 Choosing a threshold

Groundwater impacts of coal mines and coal seam gas projects are regulated under state legislation and state regulatory and management frameworks. The 0.2 m drawdown threshold used in bioregional assessments (Box 5) is consistent with the most conservative minimal impact threshold in Queensland’s Underground water impact report for the Surat Cumulative Management Area (QWC, 2012; OGIA, 2016) from the Office of Groundwater Impact Assessment and the NSW Aquifer Interference Policy (DPI, 2012). This 0.2 m drawdown threshold is also close to the practical resolution limits of modelled and measured drawdown, within the bounds of seasonal and climatic variability. The full impact and risk analysis database is provided (Dataset 9) so that readers can do their own overlays using other thresholds (see ‘How to use this assessment’).

In Queensland, ‘make good’ obligations for groundwater bores affected by coal seam gas extraction apply under Queensland’s Water Act 2000, where water pressure is predicted to fall by more than 5 m for consolidated aquifers, such as sandstone, and 2 m for unconsolidated aquifers such as sand. Additionally, Queensland’s Water Act 2000 also requires prevention or mitigation options to be developed for springs where predicted pressure reductions in the source aquifer are greater than 0.2 m. Similarly, in NSW, ‘make good’ provisions apply in most aquifers where an activity results in drawdowns greater than 2 m. The exceptions are high-priority groundwater-dependent ecosystems and culturally significant sites in the Great Artesian Basin, where ‘make good’ provisions apply if drawdowns exceed 0.2 m. ‘Make good’ provisions are legally binding agreements where any impacts caused by a petroleum and gas operation are ‘made good’, for example, in the form of compensation, improved or alternative water access, or monitoring.


Landscape groups

Which landscape groups are very unlikely to be impacted?

Key finding 6:

More than 35,000 km2 of remnant vegetation, 59,000 km of streams, 1600 km2 of wetlands and 93,000 km2 of productive landscapes within the assessment extent arevery unlikely to be impacted because they experience less than 0.2 m drawdown due to additional coal resource development.


Landscapes in the area where impacts are very unlikely (Table 2) include:

  • 35,281 km2 of remnant vegetation, including 5,846 km2 classified as 'Floodplain or lowland riverine'; 1,670 km2 classified as 'GAB GDEs'; 2,815 km2 classified as 'Non-floodplain or upland riverine'; and 24,949 km2 classified as 'Dryland remnant vegetation'
  • 59,841 km of streams, including 28,850 km of lowland streams; 23,548 km of upland streams; and 7,443 km of streams that access GAB aquifers
  • 1,612 km2 of wetlands, including 1,326 km2 classified as 'Floodplain or lowland riverine'; 11 km2 classified as 'GAB GDEs'; and 276 km2 classified as 'Non-floodplain or lowland riverine'
  • 93,044 km2 of productive landscapes used for grazing and dryland agriculture.

Key finding 7:

It is very unlikely that drawdown due to the two additional coal resource developments exceeds 0.2 m in the source aquifer of any springs in the assessment extent. This includes springs in the Springsure supergroup near Taroom, listed under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999.


The assessment extent contains 177 springs, including 153 springs that are hydrologically connected to GAB aquifers and 24 springs that access non-GAB aquifers, such as the basalt aquifers of the Main Range Volcanics.

Springs, near-permanent or temporary wetlands, and lowland streams are part of 12 landscape classes (Box 7) that all fall outside the zone of potential hydrological change (Box 5), meaning that they are very unlikely to be subject to hydrological changes due to additional coal resource development. None of the subregion’s 153 springs sourced from GAB aquifers are within 50 km of where there is a 5% chance of exceeding 0.2 m additional drawdown in the source aquifer identified for each spring by OGIA.

Within the zone of potential hydrological change, most of the area falls into two landscape groups with limited or no potential impact due to changes in the water regime arising from coal resource development:

  • 'Dryland remnant vegetation' (49% of the zone)
  • natural environments and dryland agriculture in 'Human-modified' (44% of the zone).

These areas are ruled out of potential impacts because they rely on incident rainfall and local surface water runoff and therefore are not considered water dependent for this assessment.

Which landscape groups are potentially impacted?

Outside the modelled mine pits, landscapes that are potentially impacted (Table 2) include:

  • ‘Floodplain or lowland riverine’: 20 km2 (which is 0.3% of the total in the assessment extent) of remnant vegetation and 299 km (1.0%) of streams, which are predominantly not groundwater dependent. Median drawdown due to additional coal resource development for floodplain or lowland riverine GDEs associated with alluvial or basalt aquifers is in addition to the range of natural watertable fluctuation (less than 2 m) and of a comparable magnitude
  • ‘GAB GDEs’: 76 km2 (4.4%) of remnant vegetation and 319 km (4.1%) of streams that are hydrologically connected to GAB aquifers. These include Warranna Creek to the north-east of The Range coal mine, which flows to the Auburn River in the Burnett river basin (Figure 10). Median drawdown due to additional coal resource development for GDEs associated with the GAB is in addition to the range of natural watertable fluctuation (less than 2 m) and of a comparable magnitude
  • ‘Non-floodplain or upland riverine’:12 km2 (0.4%) of remnant vegetation and 477 km (2.0%) of streams. This includes temporary upland streams and GDEs associated with basalt aquifers that flow through human-modified landscapes near New Acland Coal Mine toward Lagoon and Oakey creeks and upland streams to the west of The Range coal mine that flow into Juandah Creek and into the Dawson River. Median additional drawdown is predicted to exceed 5 m, which is likely to affect these GDEs. Local impact assessment and modelling is required to provide more detail to supplement results from this regional model
  • ‘Human-modified’: 2 km2 of water-dependent human-modified land. Median additional drawdown in excess of 2 m may affect 0.2 km2 classified as ‘Intensive use’ and ‘Production from irrigated agriculture and plantations’ that may rely on groundwater for extraction.

More detail on each landscape class, including information on water dependency, sensitivity to change and potential ecosystem relevance of hydrological changes, is contained in Section 3.4 of the impact and risk analysis for the subregion (Holland et al., 2017). Potential impacts on water-dependent assets are described in the next section.

Table 2 Extent of landscape groups in the assessment extent that are outside and in the zone of potential hydrological change (1544 km2)


Landscape group

Area, length or number

Extent of landscape group outside zone of potential hydrological change

Extent of landscape group in zone of potential hydrological changea

Floodplain or lowland riverine (including non-GAB GDEs)

Area of remnant vegetation (km2)

5,846

20

Stream network length (km)

28,850

299

GAB GDEs (riverine, springs, floodplain or non-floodplain)

Area of remnant vegetation (km2)

1,670

76

Stream network length (km)

7,443

319

GAB springs (number)

153

0

Non-floodplain or upland riverine (including non-GAB GDEs)

Area of remnant vegetation (km2)

2,815

12

Stream network length (km)

23,548

477

Non-GAB springs (number)

24

0

Human-modified

Area of non-remnant vegetation (km2)

93,044

685

Dryland remnant vegetation

Area of remnant vegetation (km2)

24,949

750

GAB = Great Artesian Basin, GDE = groundwater-dependent ecosystem. See Table 6 in Holland et al. (2017) for more detail.

Data: Bioregional Assessment Programme (Dataset 9)

FIND MORE INFORMATION

Explore landscapes in more detail at www.bioregionalassessments.gov.au/explorer/MBC/landscapes

Conceptual modelling, product 2.3 (Holland et al., 2016)

Impact and risk analysis, product 3-4 (Holland et al., 2017)

Assigning receptors to water-dependent assets, submethodology M03 (O’Grady et al., 2016)

Analysing impacts and risks, submethodology M10 (Henderson et al., 2017)

Impact and risk analysis database (Dataset 9)

Landscape classification (Dataset 14)

Landscape class spatial overlay by assessment unit (Dataset 15)

Summary of groundwater drawdown by assessment unit (Dataset 11)

Last updated:
5 January 2018