3.5.2 Ecological assets


3.5.2.1 Description

A total of 3982 water-dependent ecological assets were identified in the assessment extent of the Galilee subregion during the development of the asset register (refer to companion product 1.3 for the Galilee subregion (Sparrow et al., 2015) for details). This list of assets was compiled from 24 different sources that included 8 natural resource management organisations as well as the analysis of data provided by national, state and regional databases. Most assets came from the National atlas of groundwater dependent ecosystems (GDE Atlas) (Bureau of Meteorology, 2012). As part of this BA, each asset was assessed to ensure that it was water dependent (refer to companion product 1.3 (Sparrow et al., 2015) for details). Note that a reappraisal of available evidence on the water dependency of the assets was undertaken by the Assessment team after the publication of companion product 1.3 (Sparrow et al., 2015). This process led to the inclusion of ten additional assets in the water-dependent asset register that were not originally included (see Bioregional Assessment Programme, 2017); all of these were assets in the ‘Habitat (potential species distribution)’ class.

Of the 3982 assets in the assessment extent, a total of 241 ecological assets (about 6%) occur wholly or partly in the zone of potential hydrological change of the Galilee subregion (Table 30). These 241 ecological assets and their exposure to potential hydrological change due to additional coal development are the focus of this section. Of the 241 ecological assets, 9 assets are in the ‘Groundwater feature (subsurface)’ subgroup, 34 are in the ‘Surface water feature’ subgroup, and the majority (198) are in the ‘Vegetation’ subgroup.

The key ecological assets in the zone of potential hydrological change include a large number of groundwater-dependent ecosystems (GDEs) supporting a wide variety of vegetation types ranging from Eucalypt open forest to tussock grassland; surface water features, including riverine wetlands and springs; the potential habitat of various threatened species listed under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act); the distribution of EPBC-Act listed threatened ecological communities; the distribution of endangered regional ecosystems listed under Queensland’s Nature Conservation Act 1992; and the locations of several national parks, nature refuges and regional reserves. Some notable individual ecological assets include Doongmabulla Springs (and the associated Doongmabulla Mound Springs Nature Refuge), Scartwater Aggregation on Suttor Creek, vegetation associations supported by subsurface groundwater from the Clematis Group aquifer, Carmichael River GDE and the habitat (potential species distribution) of the black-throated finch (southern subspecies) (Poephila cincta cincta), blue devil (Eryngium fontanum) and salt pipewort (Eriocaulon carsonii.

Of the 241 ecological assets in the zone of potential hydrological change, there are 65 (27%) that only occur wholly within the zone (Table 30). Each of these ecological assets is regarded as having increased importance because the additional coal resource development in the Galilee subregion has the potential to globally impact the condition of that asset. Specifically, there are no areas outside the zone where any of these 65 assets occur.

Table 30 Ecological assets within the assessment extent and the zone of potential hydrological change of the Galilee subregion, according to asset subgroup and class


Asset subgroup

Asset class

Number of water-dependent assets in assessment extent

Number of water-dependent assets in the zone

Number of water-dependent assets confined to the zone

Surface water feature

Floodplain

5

2

0

Lake, reservoir, lagoon or estuary

45

4

2

Marsh, sedgeland, bog, spring or soak

109

6

5

River or stream reach, tributary, anabranch or bend

152

3

0

Waterhole, pool, rock pool or billabong

957

3

2

Wetland, wetland complex or swamp

171

16

3

Subtotal

1439

34

12

Groundwater feature (subsurface)

Aquifer, geological feature, alluvium or stratum

151

9

8

Subtotal

151

9

8

Vegetation

Groundwater-dependent ecosystem

2201

162

39

Habitat (potential species distribution)

186

36

6

Riparian vegetation

5

0

0

Subtotal

2392

198

45

Total

3982

241

65

Data: Bioregional Assessment Programme (Dataset 1)

There are 3741 water-dependent ecological assets that are within the assessment extent but outside the zone of potential hydrological change. Each of these assets is considered to be very unlikely (less than 5% chance) to be impacted due to additional coal resource development in the Galilee subregion.

In the following sections, assets that intersect the zone of potential hydrological change and are potentially at risk of impact due to additional coal resource development are identified. The magnitude of risk to an asset is broadly equated to the magnitude of the potential hydrological changes in potentially impacted landscape groups with which the asset is associated. For BA purposes, an asset was deemed to be associated with a landscape group if it shares an assessment unit with one or more of the landscape classes that make up that landscape group.

Assets considered ‘more at risk of hydrological changes’ as a consequence of additional coal resource development were identified. An asset ‘more at risk of hydrological changes’ was defined as one where there was at least a 50% chance of the modelled hydrological changes exceeding a defined threshold for the hydrological response variable(s) relevant for the landscape group(s) to which the asset is associated.

The hydrological thresholds chosen to identify ‘more at risk of hydrological changes’ assets within the impacted landscape groups are:

  • For ‘Streams, GDE’, ‘Floodplain, terrestrial GDE’ and ‘Non-floodplain, terrestrial GDE’ landscape groups, it is an increase in drawdown due to additional coal resource development exceeding 2.0 m.
  • For ‘Streams, non-GDE’ and ‘Streams, GDE’ landscape groups, it is an increase in the frequency of low-flow (10 ML/d) days per year of 20 days or more.

It is important to reiterate that receptor impact modelling was not undertaken for the ‘Springs’ landscape group. This means that it has not been possible for this BA to identify assets associated with the ‘Springs’ landscape group that may be ‘more at risk of hydrological changes’.

The risk to particular assets initially needs to consider these hydrological changes in conjunction with the predicted changes to receptor impact variables and ecosystem dependencies as described by qualitative mathematical modelling (and signed digraphs). A more refined assessment of risk would also need to incorporate specific local information and/or finer-resolution modelling, and a more explicit consideration of the potential pathways to impact for that asset (see Section 3.5.2.7 for an example of a more detailed analysis of risk to an individual asset).

3.5.2.2 ‘Surface water feature’ subgroup

A total of 34 assets are in the ‘Surface water feature’ subgroup in the zone of potential hydrological change. These surface water assets are classified into six classes (Table 30). The asset class within the ‘Surface water feature’ subgroup with the largest number of individual assets is the ‘Wetland, wetland complex or swamp’ class. Individual assets within the class include Lake Dalrymple, Doongmabulla Springs and Scartwater Aggregation. The latter is a riverine wetland in the channels of Suttor Creek. All of these assets are associated with landscape groups that are potentially impacted due to additional coal resource development in the Galilee subregion (Table 31).

Table 31 Number of ecological assets in the six classes of the ‘Surface water feature’ subgroup within the zone of potential hydrological change that intersect with major water-dependent landscape groups


Landscape group

Floodplain (n=2)

Lake, reservoir, lagoon or estuary (n=4)

Marsh, sedgeland, bog, spring or soak (n=6)

River or stream reach, tributary, anabranch or bend (n=3)

Waterhole, pool, rock pool or billabong (n=3)

Wetland, wetland complex or swamp (n=16)

Floodplain, terrestrial GDE

2

4

5

3

3

16

Non-floodplain, terrestrial GDE

2

0

4

3

1

8

Streams, non-GDE

2

3

0

3

0

11

Streams, GDE

2

2

5

2

3

13

Springs

1

0

6

1

0

2

GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2)

All but one of the assets intersects the ‘Floodplain, terrestrial GDE’ landscape group (Table 31). All of the assets in the ‘Marsh, sedgeland, bog, spring or soak’ class intersect with the ‘Springs’ landscape group. Twelve assets in this subgroup are confined wholly to the Galilee subregion’s zone of potential hydrological change (Table 30). These include five of the six assets in the ‘Marsh, sedgeland, bog, spring or soak’ class. Individual assets here include Doongmabulla Springs, Scartwater Aggregation, and several unnamed waterholes in the Carmichael River and Belyando River.

3.5.2.3 ‘Groundwater feature (subsurface)’ subgroup

There are nine ecological assets in this subgroup that are in the zone of potential hydrological change; these assets are all within the ‘Aquifer, geological feature, alluvium or stratum’ class. Each of these assets occurs in landscape classes that will be potentially impacted due to additional coal resource development in the Galilee subregion (Table 32). Most assets intersect with the ‘Non-floodplain, terrestrial GDE’ and ‘Streams, non-GDE’ landscape groups.

Eight of the nine assets in this subgroup are confined to the zone of potential hydrological change of the Galilee subregion. These eight assets are various vegetation communities that are GDEs dependent on the subsurface availability of groundwater sourced mainly from the Clematis Group aquifer.

Table 32 Number of ecological assets in the ‘Groundwater feature (subsurface)’ subgroup within the zone of potential hydrological change that intersect with major water-dependent landscape groups


Landscape group

Number of assets

Floodplain, terrestrial GDE

4

Non-floodplain, terrestrial GDE

7

Streams, non-GDE

7

Streams, GDE

2

Springs

1

Some assets may intersect with more than one landscape group. GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2)

3.5.2.4 ‘Vegetation’ subgroup

Most ecological assets in the zone of potential hydrological change are in the ‘Vegetation’ subgroup. Within this subgroup, assets are divided into two classes: ‘Groundwater-dependent ecosystem’ and ‘Habitat (potential species distribution)’. Each of these classes is covered separately below.

3.5.2.4.1 Groundwater-dependent ecosystem

Most assets (n=162) in the zone of potential hydrological change of the Galilee subregion are within this asset class (Table 30). Among the individual assets in this class are GDEs of varying size distributed along surface water drainages such as Cape River, Carmichael River, Cattle Creek, Dyllingo Creek, Fox Creek, Lagoon Creek, Native Companion Creek, North Creek, Sandy Creek, Suttor River and Tomahawk Creek.

The landscape group with which the largest number of assets in the ‘Groundwater-dependent ecosystem’ class intersects is ‘Floodplain, terrestrial GDE’. All but six of the individual assets occur wholly or partly in this landscape group (Table 33). The ‘Streams, GDE’ and ‘Streams, non-GDE’ landscape groups also have a large number of assets in this class.

Thirty-nine assets within this asset class only occur in the zone of potential hydrological change. These assets are distributed widely across the zone and are commonly associated with riverine systems.

Table 33 Number of ecological assets in the ‘Groundwater-dependent ecosystem’ class of the ‘Vegetation’ subgroup within the zone of potential hydrological change that intersect with major water-dependent landscape groups


Landscape group

Number of assets

Floodplain, terrestrial GDE

155

Non-floodplain, terrestrial GDE

102

Streams, non-GDE

133

Streams, GDE

137

Springs

27

GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2)

3.5.2.4.2 Habitat (potential species distribution)

A total of 36 individual assets are in the ‘Habitat (potential species distribution)’ class (Table 30). These divide readily into the following categories: (i) potential distribution of EPBC Act-listed threatened species, (ii) mapped distribution of endangered regional ecosystems under Queensland legislation, (iii) mapped distribution of EPBC Act-listed threatened ecological communities, and (iv) location of national parks, nature refuges and resources reserves.

In relation to category (i), it is important to note that the terms ‘habitat’ and ‘potential species distribution’ are synonymous in relation to assets, and that the potential species distribution or habitat does not definitely mean that either the species or its habitat is present within the modelled distribution (see Section 2.3.3 of Evans et al. (2018b)). The Department of the Environment and Energy Environmental Resources Information Network (ERIN) uses maximum entropy (MAXENT) modelling to define the geographic extent of potential species distributions based largely on physical parameters and past observations of the presence and absence of a species (Elith et al., 2011). The habitat itself, in the form of suitable vegetation types or ecosystems, is not necessarily present within the modelled potential species distribution. Furthermore, where suitable habitat does exist within the modelled potential species distribution, the species may not be known or predicted to occur there.

A further point in relation to all the four categories is that the location information (and subsequent modelling of species distribution) is ‘point in time’ in nature. As previously mentioned, location records were not updated after the water-dependent asset register was finalised for the Galilee subregion (Bioregional Assessment Programme, 2017). Thus, it is possible that some species distributions used in this BA (and possibly shown in this product) may have been subsequently updated or modified on the basis of more recently acquired data.

None of the assets in categories (i), (ii) or (iii) are located entirely within the Galilee subregion’s zone of potential hydrological change. The species that is closest to being confined to the zone is the distribution of the wetland plant, the blue devil (Eryngium fontanum). It occurs at Moses Springs in the Doongmabulla Springs complex and also further west outside the zone at Edgbaston Springs (Figure 67).

The potential distribution of 15 EPBC Act-listed threatened species occurs within the zone of potential hydrological change (Table 34). The plants include two endemic spring wetland species, the blue devil and the salt pipewort (Eriocaulon carsonii) (Figure 67). There are also two non-wetland plants, the black ironbox (Eucalyptus raveretiana), which is confined to the extreme north of the zone of potential hydrological change, and the hairy-joint grass (Arthraxon hispidus), which occurs in the north-west and south-east parts of the zone (Figure 67).

Habitat (potential species distribution) of six threatened bird species is located within the zone of potential hydrological change. Habitat is potentially available for three species of granivorous birds (Table 34): the black-throated finch (southern), star finch (eastern) and squatter pigeon (southern). Sizeable areas of potential species distribution occur within the zone for each of these species (Figure 68). In comparison, only small areas of potential species distribution occur within the zone for three other EPBC Act-listed threatened bird species: Australian painted snipe, red goshawk and painted honeyeater (Figure 69). The koala is known from a small number of sites across the zone (Figure 69). The assets in this category also include habitat (potential species distribution) of four reptile species listed as threatened under the EPBC Act (Figure 70). Habitat (potential species distribution) of all of these species includes the ‘Floodplain, terrestrial GDE’ landscape group. The potential distribution of all but one of these species (hairy-joint grass) includes the ‘Streams, GDE’ landscape group (Table 34).

Table 34 Individual ecological assets in the ‘Habitat (potential species distribution)’ class of the ‘Vegetation’ subgroup that are habitat of threatened species found within the zone of potential hydrological change that intersect with major water-dependent landscape groups


Asset namea

Floodplain, terrestrial GDE

Non-floodplain, terrestrial GDE

Streams, non-GDE

Streams, GDE

Springs

Australian Painted Snipe (Rostratula benghalensis)

Yes

No

Yes

Yes

No

Black Ironbox (Eucalyptus raveretiana)

Yes

Yes

Yes

Yes

No

Black-throated Finch (southern) (Poephila cincta cincta)

Yes

Yes

Yes

Yes

No

Blue Devil (Eryngium fontanum)

Yes

Yes

No

Yes

Yes

Dunmall’s Snake (Furina dunmalli)

Yes

Yes

Yes

Yes

Yes

Hairy-joint Grass (Arthraxon hispidus)

Yes

No

Yes

No

No

Koala (Phascolarctos cinereus)

Yes

Yes

Yes

Yes

No

Ornamental Snake (Denisonia maculata)

Yes

Yes

Yes

Yes

Yes

Painted Honeyeater (Grantiella picta)

Yes

Yes

Yes

Yes

No

Brigalow scaly-foot (Paradelma orientalis)

Yes

Yes

Yes

Yes

Yes

Red Goshawk (Erythrotriorchis radiatus)

Yes

Yes

Yes

Yes

No

Salt Pipewort (Eriocaulon carsonii)

Yes

Yes

No

Yes

Yes

Squatter Pigeon (southern) (Geophaps scripta scripta)

Yes

Yes

Yes

Yes

No

Star Finch (eastern) (Neochmia ruficauda ruficauda)

Yes

Yes

Yes

Yes

Yes

Yakka Skink (Egernia rugosa)

Yes

Yes

Yes

Yes

No

aTypology and punctuation are given as they are used in relevant legislation.

GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2)

Figure 67

Figure 67 Distribution of threatened plant species in the 'Habitat (potential species distribution)' class in the zone of potential hydrological change, overlain with groundwater-dependent ecosystem (GDE) landscape groups. Inset box (a) zooms into the area around the Doongmabulla Springs complex, highlighting distribution of salt pipewort and blue devil in relation to individual springs

These species are listed nationally under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999.

ACRD = additional coal resource development

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

Figure 68

Figure 68 Distribution of species of threatened seed-eating birds in the 'Habitat (potential species distribution)' class in the zone of potential hydrological change

These species are listed nationally under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999.

ACRD = additional coal resource development

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

Figure 69

Figure 69 Distribution of the Australian painted snipe, painted honeyeater and the koala in the 'Habitat (potential species distribution)' class in the zone of potential hydrological change, overlaid with groundwater-dependent ecosystem (GDE) landscape groups

These species are listed nationally under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999.

ACRD = additional coal resource development

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

Figure 70

Figure 70 Distribution of species of threatened reptiles in the 'Habitat (potential species distribution)' class in the zone of potential hydrological change

These species are listed nationally under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999.

ACRD = additional coal resource development

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

The habitat (potential species distribution) of ten endangered regional ecosystems occurs within the zone of potential hydrological change. These regional ecosystems occur patchily throughout the zone (Figure 71). These assets intersect with landscape groups that are potentially impacted due to additional coal resource development (Table 35). All assets intersect with the ‘Floodplain, terrestrial GDE’ landscape group and the ‘Streams, non-GDE’ landscape group. Most also intersect with the ‘Streams, GDE’ and ‘Non-floodplain, terrestrial GDE’ landscape groups (Table 35).

Table 35 Individual ecological assets in the ‘Habitat (potential species distribution)’ class of the ‘Vegetation’ subgroup that are endangered regional ecosystems located within the zone of potential hydrological change and their intersection with the major potentially impacted landscape groups


Asset namea

Floodplain, terrestrial GDE

Non-floodplain, terrestrial GDE

Streams, non-GDE

Streams, GDE

Springs

Acacia argyrodendron woodland on Cainozoic clay plains

Yes

Yes

Yes

Yes

No

Acacia cambagei woodland on Cainozoic clay plains

Yes

Yes

Yes

Yes

Yes

Acacia harpophylla and/or Casuarina cristata open forest on alluvial plains

Yes

Yes

Yes

Yes

No

Acacia harpophylla and/or Eucalyptus cambageana open woodland on Cainozoic lake beds

Yes

Yes

Yes

Yes

No

Acacia harpophylla and/or Eucalyptus cambageana open woodland to woodland on Mesozoic sediments

Yes

Yes

Yes

Yes

No

Acacia harpophylla shrubby woodland with Terminalia oblongata on Cainozoic clay plains

Yes

Yes

Yes

Yes

No

Eremophila mitchellii tall open shrubland on alluvial plains

Yes

Yes

Yes

Yes

No

Eucalyptus cambageana woodland to open forest with A. harpophylla or A. argyrodendron on Cainozoic clay plains

Yes

Yes

Yes

Yes

No

Eucalyptus melanophloia open woodland or Lysiphyllum carronii low open woodland on calcareous sandstones

Yes

Yes

Yes

Yes

No

Triodia longiceps hummock grasslands, ephemeral open herblands, and Melaleuca bracteata low open woodland on alluvial plains

Yes

Yes

Yes

Yes

Yes

aTypology and punctuation are given as they are used in the asset database.

GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2)

Figure 71

Figure 71 Distribution of endangered regional ecosystems in the 'Habitat (potential species distribution)' class in the zone of potential hydrological change, overlaid with groundwater-dependent ecosystem (GDE) landscape groups. Inset box (a) zooms into the area around the Doongmabulla Springs complex, highlighting the distribution of endangered regional ecosystems, individual springs and landscape groups

These species are listed nationally under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999.

ACRD = additional coal resource development

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

Habitat (potential species distribution) of three EPBC Act-listed threatened ecological communities (TECs) occurs within the zone of potential hydrological change. The Brigalow TEC is restricted to the eastern edge of the zone and the weeping myall woodlands to the south-east. ‘The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin’ TEC occurs only at Doongmabulla Springs (Figure 72). All of these assets intersect with landscape groups that are potentially impacted due to additional coal resource development (Table 7). All three ecological communities occur within the ‘Floodplain, terrestrial GDE’ landscape group.

Eight of the ecological assets in the ‘Habitat (potential species distribution)’ class of the ‘Vegetation’ subgroup occur within the zone of potential hydrological change and are national parks, nature reserves or resource reserves (regional parks). All of the assets in this category intersect at least one potentially impacted landscape group (Table 37). All eight ecological assets intersect with the ‘Floodplain, terrestrial GDE’ landscape group. Only one asset intersects with the ‘Springs’ landscape group: Doongmabulla Mound Springs Nature Refuge.

Six of the eight assets in this category are confined to the zone of potential hydrological change of the Galilee subregion. The two exceptions are East Top Nature Refuge and Nairana National Park.

Table 36 Individual ecological assets in the ‘Habitat (potential species distribution)’ class of the ‘Vegetation’ subgroup that are listed threatened ecological communities (TECs) under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999 within the zone of potential hydrological change and their intersection with major potentially impacted landscape groups


Asset namea

Floodplain, terrestrial GDE

Non-floodplain, terrestrial GDE

Stream, non-GDE

Stream, GDE

Springs

Brigalow (Acacia harpophylla dominant and co-dominant) TEC

Yes

Yes

Yes

Yes

No

Weeping Myall Woodlands TEC

Yes

Yes

Yes

Yes

No

The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin TEC

Yes

Yes

Yes

Yes

Yes

aTypology and punctuation are given as they are used in the asset database.

GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2)

Figure 72

Figure 72 Distribution of threatened ecological communities in the 'Habitat (potential species distribution)' class in the zone of potential hydrological change, overlaid with groundwater-dependent ecosystem (GDE) landscape groups

These species are listed nationally under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999.

ACRD = additional coal resource development, GAB = Great Artesian Basin

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

Table 37 Individual ecological assets in the ‘Habitat (potential species distribution)’ class of the ‘Vegetation’ subgroup that are nature reserves, national parks or resource reserves within the zone of potential hydrological change and their intersection with major potentially impacted landscape groups


Asset name

Floodplain, terrestrial GDE

Non-floodplain, terrestrial GDE

Streams, non-GDE

Streams, GDE

Springs

Bimblebox Nature Refuge

Yes

No

Yes

No

No

Bygana Nature Refuge

Yes

No

No

Yes

No

Bygana West Nature Refuge

Yes

Yes

Yes

Yes

No

Cudmore National Park

Yes

Yes

Yes

Yes

No

Cudmore Resources Reserve (Regional Park)

Yes

Yes

Yes

Yes

No

Doongmabulla Mound Springs Nature Reserve

Yes

Yes

No

Yes

Yes

East Top Nature Refuge

Yes

No

No

No

No

Nairana National Park

Yes

No

No

Yes

No

GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2)

3.5.2.5 Identification of ‘more at risk of hydrological changes’ assets

Of the 241 ecological assets in the zone of potential hydrological change, 148 are identified as being ‘more at risk of hydrological changes’ (see Section 3.2.5 for further details about the various risk category terms used in this BA; Table 38). That is, all or part of the area of these assets occurs within one or more of the potentially impacted landscape groups, and there is a greater than 50% chance of the modelled hydrological change exceeding the defined threshold in one or more of the hydrological response variable(s) relevant to the landscape group(s). The defined threshold for assets intersecting the ‘Streams, GDE’, ‘Floodplain, terrestrial GDE’ and ‘Non-floodplain, terrestrial GDE’ landscape groups was an increase in drawdown due to additional coal resource development exceeding 2 m. For the ‘Streams, non-GDE’ and ‘Streams, GDE’ landscape groups, the defined threshold was an increase in the frequency of low-flow (10 ML/d) days per year of 20 days or more. These thresholds were developed based on expert ecological input from within the Assessment team.

A number of assets also experienced higher levels of risk than the defined thresholds used to identify ‘more at risk of hydrological changes’ assets. The response differed depending on the hydrological response variable being considered. Specifically, when considering assets intersecting landscape groups that had groundwater drawdown as the critical hydrological response variable, 69 assets had a greater than 50% chance of the modelled hydrological change exceeding 5 m (Table 39). In contrast, when considering assets intersecting landscape groups that had frequency of low-flow days per year as the main hydrological response variable, only five ecological assets had a greater than 50% chance of the modelled hydrological change exceeding an increase of 200 or more low-flow days per year.

The ‘more at risk’ assets were mostly in the ‘Groundwater-dependent ecosystem’ class of the ‘Vegetation’ subgroup (Table 38). These include a wide range of terrestrial, riverine and wetland GDEs.

A total of 25 of the ‘more at risk’ assets were in the ‘Habitat (potential species distribution)’ class of the ‘Vegetation’ subgroup. Within this list of assets were the potential species distributions of 12 EPBC Act-listed threatened species. These species include all the birds listed as ecological assets except red goshawk (Figure 68 and Figure 69), the koala (Figure 69) and all the reptiles listed as ecological assets (Figure 70), in addition to the plants, black ironbox and hairy-joint grass (Figure 67). The mapped distributions of seven of the ten endangered regional ecosystems that occur within the zone of potential hydrological change (Table 35) are considered ‘more at risk of hydrological changes’. The mapped distributions of two of the three TECs listed under the EPBC Act (Table 36, Figure 72) are also considered to be ‘more at risk‘. Among nature reserves, national parks or resource reserves in the zone, the following are classed as ‘more at risk’: Bimblebox Nature Refuge, Cudmore National Park, Cudmore Resource Reserve and Nairana National Park.

The risk to the particular water-dependent assets identified here needs to consider these hydrological changes in conjunction with the predicted changes to receptor impact variables (for relevant landscape groups) and ecosystem dependencies as described by qualitative mathematical modelling (and signed digraphs). A more refined assessment of risk would need to also incorporate local information or finer-resolution modelling, and a more explicit consideration of the potential pathways to impact for that asset.

Table 38 Summary of the number of ‘more at risk of hydrological changes’ ecological assets within the zone of potential hydrological change, according to asset subgroup and class


Asset subgroup

Asset class

More at risk of hydrological changes

Surface water feature

Floodplain

0

Lake, reservoir, lagoon or estuary

2

Marsh, sedgeland, bog, spring or soak

0

River or stream reach, tributary, anabranch or bend

2

Waterhole, pool, rock pool or billabong

2

Wetland, wetland complex or swamp

10

Subtotal

16

Groundwater feature (subsurface)

Aquifer, geological feature, alluvium or stratum

1

Subtotal

1

Vegetation

Groundwater-dependent ecosystem

106

Habitat (potential species distribution)

25

Riparian vegetation

0

Subtotal

131

Total

148

Data: Bioregional Assessment Programme (Dataset 1)


Table 39 Summary of the number of ecological assets exceeding defined categories of modelled hydrological change for those assets that are in landscape groups where the hydrological response variable used for receptor impact modelling is groundwater drawdown within the zone of potential hydrological change


Asset subgroup

Asset class

Number of assets with additional drawdown ≥0.2 m

Number of assets with additional drawdown ≥2 m

Number of assets with additional drawdown ≥5 m

5th

50th

95th

5th

50th

95th

5th

50th

95th

Surface water feature

Floodplain

1

1

2

1

1

1

1

1

1

Lake, reservoir, lagoon or estuary

1

1

4

0

1

1

0

0

1

Marsh, sedgeland, bog, spring or soak

0

1

6

0

0

1

0

0

0

River or stream reach, tributary, anabranch or bend

2

2

3

2

2

2

2

2

2

Waterhole, pool, rock pool or billabong

1

1

3

0

0

1

0

0

0

Wetland, wetland complex or swamp

6

7

12

4

6

6

2

4

6

Groundwater feature (subsurface)

Aquifer, geological feature, alluvium or stratum

1

1

9

1

1

2

0

1

1

Vegetation

Groundwater-dependent ecosystem

61

85

137

42

57

78

27

43

59

Habitat (potential species distribution)

20

24

29

17

20

23

9

18

19

Total

93

123

205

67

88

115

41

69

89

The assets potentially exposed to ≥0.2, ≥2 and ≥5 m additional drawdown is shown for the 5th, 50th and 95th percentile estimates of the maximum difference in drawdown (dmax) between the coal resource development pathway (CRDP) and baseline, due to additional coal resource development.

Data: Bioregional Assessment Programme (Dataset 1, Dataset 3)

Table 40 Summary of the number of ecological assets exceeding defined categories of modelled hydrological change for those assets that are in landscape groups where the hydrological response variable used for receptor impact modelling is increase in low-flow days per year within the zone of potential hydrological change


Asset subgroup

Asset class

Number of assets for length with increases of 3 low-flow days per year

Number of assets for length with increases of 20 low-flow days per year

Number of assets for length with increases of 80 low-flow days per year

Number of assets for length with increases of 200 low-flow days per year

5th

50th

95th

5th

50th

95th

5th

50th

95th

5th

50th

95th

Surface water feature

Floodplain

1

1

1

0

1

1

0

1

1

0

0

1

Lake, reservoir, lagoon or estuary

2

2

2

0

2

2

0

2

2

0

0

2

Marsh, sedgeland, bog, spring or soak

0

0

0

0

0

0

0

0

0

0

0

0

River or stream reach, tributary, anabranch or bend

2

2

2

0

2

2

0

2

2

0

0

2

Waterhole, pool, rock pool or billabong

2

2

2

0

2

2

0

2

2

0

0

2

Wetland, wetland complex or swamp

8

9

9

0

9

9

0

7

9

0

0

7

Groundwater feature (subsurface)

Aquifer, geological feature, alluvium or stratum

0

0

0

0

0

0

0

0

0

0

0

0

Vegetation

Groundwater-dependent ecosystem

84

95

95

0

93

95

0

74

95

0

4

77

Habitat (potential species distribution)

21

21

21

0

21

21

0

17

21

0

1

19

Total

120

132

132

0

130

132

0

105

132

0

5

110

‘Low-flow days’ is the number of low-flow days per year. This is typically reported as the maximum change due to additional coal resource development over the 90-year period (from 2013 to 2102). The threshold for low-flow days is the 10th percentile from the simulated 90-year period.

Data: Bioregional Assessment Programme (Dataset 1, Dataset 3)

3.5.2.6 Assets and the ‘Springs’ landscape group

The ‘Springs’ landscape group is potentially impacted due to modelled additional coal resource development. The potential impacts and risks for the ‘Springs’ landscape group due to groundwater drawdown in the zone of potential hydrological change are detailed in Section 3.4.3. Section 3.4.3 also outlines the two interpretations of the hydrogeology for the source aquifer of the Doongmabulla Springs complex. Section 3.3.2 presents the two modelling conceptualisations that were used in the groundwater analytic element model (AEM), which are also relevant to understanding the potential impacts of coal resource development on these important ecological assets. In particular, the modelling results from the alternative AEM conceptualisation (Section 3.3.2) are considered to be more appropriate for assessing impacts to some specific points in the landscape (such as springs) that occur in areas where the uppermost Quaternary alluvium and Cenozoic sediment aquifer (the uppermost aquifer layer modelled in the AEM) is absent or not in direct (unimpeded) connection with the mining areas. Further information on the hydrological regimes and connectivity of the Doongmabulla Springs complex is also provided in Section 2.7.3 of companion product 2.7 for the Galilee subregion (Ickowicz et al., 2018).

The focus of this current section is on ecological assets that intersect with the ‘Springs’ landscape group and, in lieu of receptor impact modelling, on using the available lines of information to assess potential impacts on and risks to these assets. A large number of high-profile assets in the water-dependent asset register intersect with the ‘Springs’ landscape group. Although the 200 springs in this landscape group occupy less than 1% of the area of the zone of potential hydrological change, a total of 48 individual ecological assets (20% of all ecological assets in the zone) intersect with the ‘Springs’ landscape group (Table 39). Of these assets, 16 are confined entirely to the zone (i.e. do not occur anywhere outside the zone).

Most ecological assets associated with the ‘Springs’ landscape group are predominantly located in and around the Doongmabulla Springs complex. However, the Mellaluka Springs GDE is also an ecological asset listed in the asset register. Individual ecological assets located within the Doongmabulla Springs complex include the springs themselves (listed as a wetland complex in the ‘Surface water feature’ subgroup); the Doongmabulla Mound Springs Nature Refuge; habitat (potential species distribution) of an EPBC Act-listed TEC, ‘The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin’; and habitat (potential species distribution) of two EPBC Act-listed threatened plant species: blue devil and salt pipewort (Figure 67 and Figure 72). Blue devil is an erect perennial herb, whereas salt pipewort is a small aquatic herb that grows in shallow water (in depths as low as 10 cm). In addition, a sociocultural asset, Doongmabulla Spring Natural Indicative Place, is located within the Doongmabulla Springs complex (see Section 3.5.4 for information about potential impacts to sociocultural assets).

Table 41 Ecological assets that intersect with the 'Springs' landscape group


Asset ID

Asset name (shortened)a

2677

Aquifer boundary – Birkhead Formation

2694

Floodplain in Burdekin River region

2550

Clematis Formation_Eucalyptus low open woodlands with tussock grass

2560

Clematis Formation_Eucalyptus open forests with a grassy understorey

2570

Clematis Formation_Mulga woodlands and shrublands

2588

Clematis Formation_Tropical mixed species forests and woodlands

2644

Tasman_Acacia (+/- low) open woodlands and sparse shrublands with a shrubby understorey

2651

Tasman_Mallee with hummock grassland

2738

Rivers in the Burdekin River region

408

Doongmabulla Springs

2826

Wetland/s of Eucalyptus woodlands with a tussock grass understorey

27452

Cattle Creek GDE

27454

Cattle Creek GDE Moderate potential for GW interaction

28432

Dyllingo Creek GDE

28433

Dyllingo Creek GDE Low potential for GW interaction

28434

Dyllingo Creek GDE Moderate potential for GW interaction

28666

Eucalyptus low open woodlands with hummock grass Broken River Burdekin River Spring GDE

29326

Eucalyptus low open woodlands with hummock grass Broken River Burdekin River Spring GDE

29334

Eucalyptus low open woodlands with hummock grass Broken River Burdekin River Wetland GDE

24673

Eucalyptus open woodlands with a grassy understorey GDE Low potential for GDE interaction

24674

Eucalyptus open woodlands with a grassy understorey GDE Moderate potential for GDE interaction

24684

Eucalyptus open woodlands with shrubby understorey GDE Moderate potential for GDE interaction

24691

Eucalyptus populnea or E. melanophloia (or E. whitei) dry woodlands to open-woodlands on sandplains or depositional plains GDE High potential for GW interaction

24693

Eucalyptus populnea or E. melanophloia (or E. whitei) dry woodlands to open-woodlands on sandplains or depositional plains GDE Low potential for GW interaction

24694

Eucalyptus populnea or E. melanophloia (or E. whitei) dry woodlands to open-woodlands on sandplains or depositional plains GDE Moderate potential for GW interaction

24711

Eucalyptus spp. dominated open-forest and woodlands drainage lines and alluvial plains GDE

24704

Eucalyptus spp. low open-woodland often with Triodia spp. dominated ground layer GDE

30316

Eucalyptus woodlands with a tussock grass understorey Broken River Burdekin River Spring GDE

30321

Eucalyptus woodlands with a tussock grass understorey Broken River Burdekin River wetland GDE

30324

Eucalyptus woodlands with a tussock grass understorey Broken River Burdekin River wetland GDE

31762

Hector GDE

31876

Hummock grasslands Broken River Burdekin River Spring GDE

33462

Mellaluka Springs GDE

24921

Other Acacia forests and woodlands GDE High potential for GW interaction

24924

Other Acacia forests and woodlands GDE Moderate potential for GW interaction

36056

Other tussock grasslands Broken River Burdekin River Spring GDE

36061

Other tussock grasslands Broken River Burdekin River Wetland GDE

25031

Wetlands associated with permanent lakes and swamps, as well as ephemeral lakes, claypans and swamps. Includes fringing woodlands and shrublands GDE High potential for GW interaction

23461

Acacia cambagei woodland on Cainozoic clay plains Endangered Regional Ecosystem

216

Doongmabulla Mound Springs Nature Refuge

2085

Potential distribution of Blue Devil (Eryngium fontanum)

2147

Potential distribution of Dunmall’s Snake (Furina dunmalli)

2102

Potential distribution of Ornamental Snake (Denisonia maculata)

2186

Potential distribution of Paradelma orientalis

2107

Potential distribution of Salt pipewort (Eriocaulon carsonii)

2111

Potential distribution of Star Finch (eastern) (Neochima ruficauda ruficauda)

2210

The community of native species dependent on natural discharge of groundwater from the Great Artesian Basin threatened ecological community

23502

Triodia longiceps hummock grassland, ephemeral open herblands, and Melaleuca bracteata low woodland on alluvial plains Endangered Regional Ecosystem (as dominant component)

aTypology and punctuation are given as they are used in the asset database.

GDE = groundwater-dependent ecosystem; GW = groundwater

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2)

Fensham et al. (2016) described the morphology and distribution of the various spring groups that comprise the Doongmabulla Springs complex. In general, springs underlain by the Moolayember Formation are termed ‘discharge springs’ (see Figure 41 in Section 3.4), and some of these have a distinctive mounded morphological structure. At some locations though, the original morphology of the springs is uncertain due to various types of anthropogenic modification (e.g. Joshua Spring has been extensively modified through construction of a turkey’s nest dam for use on the local pastoral lease). Springs to the east of the discharge springs (Figure 41 in Section 3.4) are situated near the base of topographic slopes within or near areas of outcropping Triassic bedrock (i.e. Clematis Group or Dunda beds). These are termed ‘outcrop springs’ by Fensham et al. (2016). The Little Moses and Yukunna Kumoo spring groups are underlain by the Clematis Group, whereas Dusk and Surprise spring groups occur on the Dunda beds outcrop. Groundwater discharges from some springs and contributes baseflow to Dyllingo Creek and the Carmichael River, and into alluvium associated within these stream valleys.

The signed digraph models for the ‘Springs’ landscape group identify the rate of groundwater flow as a critical factor in maintaining the aquatic community of springs (see companion product 2.7 for the Galilee subregion (Ickowicz et al., 2018)). Groundwater flow from the source aquifer needs to be at a rate that maintains a damp or submerged state in the spring such that the surface does not dry. An increase in groundwater flow above this threshold supports a wetted-area regime around the perimeter and downstream of the spring. Qualitative mathematical modelling indicated a zero or ambiguous response for most of the biological variables in the system to depletion of groundwater and available subsurface water. The models predicted a positive response for macrophytes (submerged and floating) but only for the cumulative impact scenario where subsurface water decreased and groundwater drawdown did not occur (see companion product 2.7 for the Galilee subregion (Ickowicz et al., 2018)).

The use of the Landsat archive of Digital Earth Australia enables the qualitative modelling predictions for the ‘Springs’ landscape group to be examined through time (i.e. over the past 30 years) within the zone of potential hydrological change (see Section 3.2.3.3 for further information about Digital Earth Australia and its application to the BA). The distribution of surface water and wet vegetation (Figure 73) as identified by the tasselled cap wetness (TCW) index derived from the Landsat archive shows that wet areas in surface drainages persist along Dyllingo Creek and the Carmichael River (even in dry years). These occur in the vicinity of the Doongmabulla Springs complex as well as downstream along the Carmichael River towards its confluence with the Belyando River. Surface water and areas of wetted vegetation are not temporally persistent in most tributary streams, except for isolated ponds (e.g. the previously unmapped water features located along some streamlines in Figure 73). The different discharge spring groups also show wide variation in persistence of water and wetted vegetation at surface (Figure 73). For instance, spring pools at the Moses-Keelback and Wobbly springs have remained persistent over the last 30 years, whereas only a relatively minor response is evident in the wetness index for the Mouldy Crumpet springs. The difference in response may have some bearing on localised differences in the water budgets and local geomorphology for individual spring groups. For example, springs with more persistent occurrence of water at surface may have a discharge rate that generally exceeds the evaporation rate, with the local geomorphology allowing for water to be ponded at surface. In general, outcrop springs associated with the Clematis Group aquifer (e.g. Yukunna Kumoo spring group) appear to be temporally persistent and have a relatively high wetness index, whereas outcrop springs that occur on areas of outcropping Dunda beds (e.g. Surprise and Dusk spring groups) have a lower wetness index. Visual inspection of the TCW index mapping for this area indicates that there may be more spring vents in the vicinity of Surprise and Dusk springs than have previously been mapped (Figure 73).

Hovmöller time-series plots (see Section 3.2) provide a useful tool to evaluate how the Landsat response for different spring groups varies over a 30-year period (1987 to 2016). The time-series response for two transects (Transect 1 and Transect 2, as shown in Figure 73) is depicted for various springs in the Doongmabulla Springs complex, using the TCW index and normalised difference vegetation index (NVDI). Analysis of these plots provides clear indications that there are significant variations in the distribution and availability of water in the vicinity of different springs groups within the Doongmabulla Springs complex. Such internal complexity may complicate the downscaling of impacts and risks from the scale of a spring complex to that of a spring group, as well as for their ongoing monitoring and management.

Stepping Stone and Mouldy Crumpet spring groups are not readily apparent on the TCW Hovmöller plot (Figure 74). It could be that discharge at these springs is too low to support wetted vegetation or spring pools that are extensive enough to be detected by the Landsat sensors (at least for the past 30-year period of the Landsat record). The highest TCW response in Figure 74 occurs around the channel of Dyllingo Creek. On the northern bank of the creek, it appears the Joshua Springs turkey’s nest dam was empty prior to 1992 but has been relatively full since. The NDVI (Figure 74) plot shows that narrow bands of permanent and stable vegetation occur around the Cattle Creek and Dyllingo Creek channels. Vegetation around Stepping Stone and Mouldy Crumpet spring groups is patchy and varies on an annual basis with the greatest extent occurring during the wet season, which suggests that long-term groundwater supply may be less reliable. In the vicinity of Mouldy Crumpet springs, vegetation was most extensive during relatively wetter seasons that occurred in 1992, 1998 to 2001, and 2010 to 2011. Some changes in land cover or land use may have occurred up slope of the Joshua Spring turkey’s nest dam around 1990.

The Hovmöller time-series plot for Transect 2 (Figure 75, location shown in Figure 73) intersects the Moses, Keelback and Wobbly spring groups. From the TCW response, landscape wetness around the Moses spring group is generally only detectable during the wet season. However, a pool fed by outflows from the Keelback and Moses springs is apparent. The TCW response suggests that since 1994 this pool has been a significant feature, remaining fairly constant in extent (approximately 200 m long) year round (although this pool appears to have diminished between 1988 and 1994). Another spring-fed pool, downstream of Moses and Keelback springs at the confluence of Cattle and Dyllingo creeks, shows more seasonal variation with a lower wetness index than the pool upstream. However, it is still largely present year round. While minimal variation in greenness is evident in the NDVI response here (Figure 75), it appears that vegetation cover has been relatively stable since 1988 (when data acquisition commenced).

Combining these remotely sensed observations with the signed-digraph models and qualitative mathematical modelling for the ‘Springs’ landscape group indicates that there is likely to be considerable variability in response to groundwater depletion among the many individual springs and spring groups that comprise the Doongmabulla Springs complex. Further, this inherent variability will likely mean that different levels of groundwater drawdown may potentially impact the ecological functioning of different springs and spring groups. This is a noteworthy set of conclusions given that all 187 springs in the Doongmabulla Springs complex are considered for this BA as a single ecological asset.

As has been emphasised previously the potential impact of groundwater drawdown due to additional coal resource development on these assets depends on the interpretation of the source aquifer(s) for Doongmabulla Springs (Section 3.4 and companion product 2.6.2 (Peeters et al., 2018)). The identity of the source aquifer for the Doongmabulla Springs complex has been contentious and the subject of previous scientific and legal dispute. Further information on the competing arguments for the source aquifer of these springs is provided in Section 3.4. Other references include: JBT Consulting (2015), Webb (2015), Currell (2016), Currell et al. (2017), Evans et al. (2018b) and Fensham et al. (2016).

As detailed in Section 3.4, the Clematis Group aquifer is considered the most plausible primary source aquifer for the Doongmabulla Springs complex, with the Dunda beds contributing minor volumes of groundwater to the easternmost spring groups in the complex (Dusk and Surprise, Figure 73). Leakage through the Moolayember Formation aquitard from the regional groundwater system in confined portions of the Clematis Group aquifer is the likely source for the discharge springs in the western part of the complex (Figure 73). In contrast, more localised groundwater flow in unconfined parts of the Clematis Group aquifer is considered the main source for springs near areas of Clematis Group outcrop (Little Moses and Yukunna Kumoo, Figure 73). Overall, it is inferred from the available evidence that the Doongmabulla Springs complex may represent a regional groundwater discharge feature sourced from the Clematis Group aquifer.

The identity of the source aquifer determines the nature of the impact from additional coal resource development, specifically aquifer depressurisation, on the assets related to the Doongmabulla Springs complex. If the source aquifer is primarily the Clematis Group aquifer then the potential exists for hydrological and ecological impact. Results for cumulative drawdown for both conceptual models used for the Galilee subregion’s AEM are presented in Section 3.4. Probabilistic modelling results based on both groundwater model conceptualisations show that 181 of the 187 springs in the Doongmabulla Springs complex have a 5% chance of experiencing additional groundwater drawdown in excess of 0.2 m. The original conceptualisation also predicts that there is also a 50% chance of these 181 springs experiencing this level of drawdown. In comparison, the alternative conceptualisation predicts that none of the springs in the Doongmabulla Springs complex would experience greater than 0.2 m of drawdown at the 50th percentile (median) of all model runs. Further, the original conceptualisation predicts that 120 springs in the Doongmabulla Springs complex have a less than 5% chance (very unlikely) of experiencing additional groundwater drawdown in excess of 2 m (there are no model results that exceed 2 m of drawdown at either the 5th, 50th or 95th percentile using the alternative conceptualisation). Section 3.4 suggests that results for the alternative groundwater modelling conceptualisation are more applicable for assessing drawdown at the Doongmabulla Springs complex (the rationale for this assessment is detailed in Section 3.3.2). In addition, and although not directly comparable due to major differences in modelling approach and development scenario, the peak drawdown at the springs from the proposed Carmichael Coal mine development (the mine nearest to these springs) will be about 0.1 to 0.3 m (Currell et al., 2017; GHD, 2013a).

In summary, the following statements can be made about the group of ecological assets that intersects the Doongmabulla Springs complex. First, the weight of available scientific evidence presented in this product, and in companion products 2.1-2.2 (Evans et al., 2018a) and 2.7 (Ickowicz et al., 2018), indicates that the source aquifer for these assets is primarily the Clematis Group aquifer. Second, both groundwater model conceptualisations used in this BA predict that 181 of the 187 springs in the Doongmabulla Springs complex have a 5% chance of experiencing additional groundwater drawdown in excess of 0.2 m. Last, consideration of multiple lines of evidence – including signed digraph models, qualitative mathematical modelling, archived Landsat imagery and ecological knowledge of the threatened vegetation species – indicates that this predicted level of drawdown will impact the ecological functioning of some ecological assets; however, there will be considerable variation in response across different springs and spring complexes. This final point underscores the need for additional local-scale analysis using more detailed geological, hydrological and ecological data to better understand the potential impact responses for individual springs and spring complexes.

Figure 73

Figure 73 Tasselled cap wetness index map - Doongmabulla Springs complex

The ‘wetness index’ represents the percentage of time observed as ‘wet’, based on the tasselled cap wetness (TCW) index. In the period 1987 to 2016, it is the proportion of times a pixel in the Landsat image archive exceeds a TCW index threshold. Each pixel represents a 25 x 25 m square area. A value of ‘1’ represents permanent water, whereas ‘0’ represents dry land and vegetation. Cenozoic sediment cover occurs in areas of this map where outcropping Triassic rocks of the Moolayember Formation, Clematis Sandstone and Dunda beds are not shown.

Data: Queensland Department of Natural Resources and Mines (Dataset 5); Bioregional Assessment Programme (Dataset 6); Queensland Department of State Development Infrastructure and Planning (Dataset 7)


Figure 74

Figure 74 Time - Landsat transect (Transect 1) through the Stepping Stone, Mouldy Crumpet and Joshua spring groups - Doongmabulla Springs complex

Middle panel shows wetness index response above a threshold of –400. Right-hand panel shows normalised vegetation difference index (NVDI) response. Location of Transect 1 on Figure 73.

Data: Bioregional Assessment Programme (Dataset 6)

Figure 75

Figure 75 Time - Landsat transect (Transect 2) through the Moses, Keelback and Wobbly spring groups - Doongmabulla Springs complex

Middle panel shows wetness index response above a threshold of –400. Right-hand panel shows normalised vegetation difference index (NVDI) response. Location of Transect 1 on Figure 73.

Data: Bioregional Assessment Programme (Dataset 6)

3.5.2.7 Assessing potential impacts on individual ecological water-dependent assets: a case study focused on the potential distribution of black ironbox

Within the operational constraints of the BAs it is not possible to assess potential impacts on each of the 241 ecological water-dependent assets within the zone of potential hydrological change. Instead, this section provides a case study to illustrate how multiple lines of available hydrological and ecological evidence may be used to assess potential impacts on individual assets. The detailed asset analysis presented here may assist future users of this BA to undertake a similar type of assessment, in order to develop a better understanding of potential impacts on, and risks to, a particular asset of interest.

The ecological asset selected for the detailed assessment presented here is the ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’. This is asset identification number 2126 in the water-dependent asset register for the Galilee subregion (Bioregional Assessment Programme, 2017). Black ironbox is listed as vulnerable nationally under the EPBC Act. Black ironbox grows to 25 m in height and mostly occurs along watercourses and on floodplains (Figure 76), although it may also occur (less commonly) in open woodland away from watercourses.

Black ironbox does not grow in pure stands, but rather is co-dominant with other tree species, including river red gum (E. camaldulensis), Moreton Bay ash (Corymbia tessellaris), river oak (Casuarina cunninghamiana) and weeping paperbark (Melaleuca fluviatilis). Black ironbox occurs mostly in coastal and sub-coastal parts of central Queensland, but is also recorded along the Suttor River (and its upper tributaries) in the Galilee assessment extent. It grows on soils that include sands, loams, light clays and cracking clays at up to 300 m above sea level.

The ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’ intersects with about 87 km2 of vegetation ecosystems and 145 km of stream network in the northern part of the zone of potential hydrological change for the Galilee subregion (Figure 76). As noted previously, the potential geographic extent of this and other species within the zone is based on maximum entropy (MAXENT) modelling that relies largely on physical parameters and past observations of the presence and absence of the species. This means that the modelled extent of this asset within the zone has not been validated by field-based studies undertaken for this BA. Further work, which is beyond the scope of this assessment, would be needed to confirm the actual presence and distribution of black ironbox in the areas of the zone where it is modelled to occur.

The ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’ overlies parts of the northernmost area of the surface water zone of potential hydrological change, along sections of the Suttor River just upstream of Lake Dalrymple (Figure 21). However, this asset extent does not intersect with the groundwater zone of potential hydrological change (Figure 20). The asset extent within the surface water zone intersects areas that may experience hydrological changes due to additional coal resource development, in particular an increase in the number of zero-flow days per year (Figure 28). This includes the area within the zone of potential hydrological change where surface water modelling predicts the largest increases in the number of zero-flow days (Section 3.3.3). These modelled hydrological changes occur in the main channel of the Belyando River, and the Suttor River downstream of its junction with the Belyando, in particular, the approximately 250 km stretch of this river network from downstream of the junction with Native Companion Creek to Lake Dalrymple (Burdekin Falls Dam).

Figure 76

Figure 76 Intersection of 'potential distribution of Black Ironbox (Eucalyptus raveretiana)' and landscape groups in the northern part of the zone of potential hydrological change for the Galilee subregion

The ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’ is asset identification number 2126 in the water-dependent asset register for the Galilee subregion

Data: Bioregional Assessment Programme (Dataset 1, Dataset 2)

Along the northernmost part of the Suttor River (above the junction with Lake Dalrymple), there is a 5% chance that low-flow days will increase by 3 to 20 days per year in both the short-term period (2013 to 2042) and the long-term period (2073 to 2102). In addition, the modelling indicates that there is a 5% chance that low-flow spells will increase by 3 to 10 days per year in the long-term period (2073 to 2102) and that overbank flows will decrease by 0.02 to 0.05 events per year over the short-term period (2013 to 2042) (meaning one fewer overbank flow every 20 to 50 years on average) (Figure 48 and Figure 49). Hydrological changes (groundwater or surface water) are not predicted along the Cape River upstream of the junction with the Suttor River. As mentioned, changes to the groundwater system in areas where the black ironbox occurs in the zone are very unlikely as the asset extent does not intersect with the groundwater zone of potential hydrological change for the Galilee subregion (Figure 20).

In this case study, the intersection of landscape groups with the extent of individual assets is used to assess potential impacts to the natural and human-modified ecosystems represented by each landscape group. Seven landscape groups are contained within the asset extent of the ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’ within the zone of potential hydrological change (Table 42). This includes a relatively small area of vegetation (14.3 km2) that is not considered to be water-dependent as it overlaps with the ‘Dryland’ and ‘Floodplain, non-wetland’ landscape groups. This small area of non-water dependent vegetation within the asset extent likely reflects the challenges of integrating datasets and assessment methods at different scales to estimate the geographic distribution of the asset and the overlapping landscape groups.

Most of the remaining asset extent within the zone is classified as groundwater-dependent vegetation (65.2 km2) (the ‘Floodplain, terrestrial GDE‘ and the ‘Floodplain, wetland GDE’ landscape groups) or groundwater-dependent streams (145 km) (‘Streams, GDE’). Two of the four receptor impact models developed for this assessment (‘Floodplain, terrestrial GDE’ and ‘Woody riparian vegetation’) are relevant when assessing potential impacts on the ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’ within the zone. Further details about the development of these receptor impact models is in companion product 2.7 for the Galilee subregion (Ickowicz et al., 2018), with the application of these models discussed in Section 3.4.

The ‘Floodplain, terrestrial GDE’ receptor impact model predicts changes to percent foliage cover of floodplain trees, such as Eucalyptus, Corymbia or Acacia species that dominate the alluvial river and creek flats in the ‘Floodplain, terrestrial GDE’ landscape group. These species co-occur with Eucalyptus raveretiana (as described above). The asset occurs in areas of the ‘Floodplain, terrestrial GDE’ landscape group that are considered to be ‘at minimal risk’ due to additional coal resource development (Figure 62).

Within the zone of potential hydrological change, most streams within the asset extent are classified in the ‘Streams, GDE’ (129 km or 89% of streams) landscape group. The ‘Woody riparian vegetation’ receptor impact model predicts changes to the percent foliage cover of Eucalyptus camaldulensis and Melaleuca spp. in the ‘Streams, GDE’ landscape group. The ‘High-flow macroinvertebrate’ receptor impact model is relevant to both the ‘Streams, GDE’ and ‘Streams, non-GDE’ landscape groups. However, this receptor impact model is not relevant to assessing potential impacts to the black ironbox asset as it predicts changes to the density of mayfly nymphs (order Ephemeroptera in the family Baetidae of the genus Offadens) in riffle habitat, 3 months after the end of the wet season.

Considering the multiple lines of evidence generated through this BA, as well as the existing knowledge base about the hydrological dependence and ecological characteristics of the black ironbox, allows for an assessment of potential impacts on this asset due to additional coal resource development. Integrating this information with the experts’ opinions developed through the receptor impact modelling process provides strong evidence that potential impacts to the ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’ are very unlikely within the zone of potential hydrological change as:

  • The asset extent does not intersect with the groundwater zone of potential hydrological change, meaning that groundwater drawdown due to modelled coal resource development is very unlikely to impact this asset.
  • The ‘Floodplain, terrestrial GDE’ receptor impact model relevant to the ‘Floodplain, terrestrial GDE’ landscape group predicts ‘minimal risk’ within the asset extent (i.e. decreases of less than 5% foliage cover of floodplain trees (see Section 3.4.6)).
  • The ‘Woody riparian vegetation’ receptor impact model relevant to the ‘Streams, GDE’ landscape group predicts ‘minimal risk’ within the asset extent (i.e. decreases of less than 5% foliage cover of floodplain trees (see Section 3.4.4)).

Table 42 Landscape groups within the zone of potential hydrological change for the Galilee subregion and the extent of their overlap with the ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’


Landscape group

Area or length

Extent in zone of potential hydrological change

Extent overlapping with ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’

Dryland

Area (km2)

8,134

9.1

Floodplain, disconnected wetland

Area (km2)

19

7.2

Floodplain, non-wetland

Area (km2)

2,098

5.2

Floodplain, terrestrial GDE

Area (km2)

2,433

40.7

Floodplain, wetland GDE

Area (km2)

153

24.5

Total area

Area (km2)

12,837

86.7

Streams, GDE

Length (km)

2,801

129

Streams, non-GDE

Length (km)

3,484

16

Total length

Length (km)

6,285

145

The ‘potential distribution of Black Ironbox (Eucalyptus raveretiana)’ is an ecological water-dependent asset of the ‘Vegetation’ subgroup, and is listed as asset identification number 2126 in the water-dependent asset register for the Galilee subregion. The three non-floodplain landscape groups that occur in the Galilee assessment extent are not included in this table as they do not intersect with the black ironbox asset extent in the zone of potential hydrological change.

GDE = groundwater-dependent ecosystem

Data: Bioregional Assessment Programme (Dataset 1)

Last updated:
4 January 2019
Thumbnail of the Galilee subregion

Product Finalisation date

2018
PRODUCT CONTENTS

ASSESSMENT