often contain a large number and diverse range of . To deal with this complexity, a landscape classification was developed to group assets that function similarly with respect to hydrology. This section describes the methodology and used to arrive at the landscape classification for ecological assets within the Gloucester . were defined within five broad groups:
- ‘Riverine’ landscape group. Landscape classes in the riverine are based on ecohydrology and substrate layers supplied by the NSW Office of Water () and derived from the River Styles® Framework (River Styles) in NSW (). The use of the River Styles offers significant advantages over frameworks such as the (Bureau of Meteorology, ) as ecologically relevant information is associated with River Styles via the application of the River Condition Index () by relevant NSW state agencies. The RCI was developed to combine multiple indices into a single condition score for monitoring, evaluating and reporting on river condition. The RCI is based on the Framework for Assessing River and Wetland Health (FARWH) (). In addition to the RCI, the indices that contribute to the RCI and the ecological datasets that underpin these indices are available for River Styles and can be used within a , as required, for modelling of coal seam gas (CSG) and/or large coal mining development on riverine classes.
- ‘Groundwater-dependent ecosystem (GDE)’ landscape group. Landscape classes in the landscape group were based on the NSW Office of Water mapping of GDEs (NSW Department of Primary Industries, ). The NSW Office of Water’s methodology combines vegetation mapping, optical remote sensing (from the Landsat and MODIS instruments), and level data (where available) with expert knowledge to compile maps of high probability, high ecological value and high-priority GDEs. This data source was chosen ahead of alternatives such as the NSW Office of Environment and Heritage’s (NSW OEH) mapping of wetlands (NSW Office of Environment and Heritage, ) and the National atlas of groundwater dependent ecosystems (Bureau of Meteorology, ) owing to its local detail and currency. Furthermore, the vegetation classification intrinsic to (NSW Office of Water) allowed the classification of landscape classes to reflect the underlying function of the wetlands with which they are associated. By contrast, the NSW OEH (NSW Office of Environment and Heritage, ) mapping of wetlands was largely restricted to coastal areas, was last updated in 2004 and does not report underlying wetland function.
- ‘Estuarine’ landscape group. Landscape classes in the estuarine landscape group were based on both the ecohydrology and substrate layers described above (NSW Office of Water, ) for estuarine river reaches, and the mapping of saline wetlands provided by the NSW OEH (Department of Primary Industries, ).
- ‘Non-GDE’ landscape group. Native vegetation that was not identified as being dependent was classified as ‘native vegetation’ based on the Hunter Native Vegetation Mapping (Bioregional Assessment Programme, ).
- ‘Economic land use’ landscape group. Remaining areas of the Gloucester PAE that were still unclassified were assigned a landscape classification based on the Australian Land Use and Management (ALUM) Classification of Australia (for catchment-scale land use classification in Australia), Update 14 (Australian Bureau of Agricultural and Resource Economics Bureau of Rural Sciences, ).
Table 3 Summary of landscape classes in the Gloucester preliminary assessment extent
For clarity, only the hydrology component of the landscape classification is illustrated (perennial, intermittent or estuarine) and the ‘Water’ landscape class in the economic land use group is omitted. GDE = groundwater-dependent ecosystem. The Australian Land Use and Management (ALUM) land use data used for (b) are current for this area as at 1999 and hence the Duralie Coal Mine, which commenced after then, is not shown.
The River Styles classification of rivers is widely used in NSW but is largely based on river geomorphology, which primarily focuses on the physical structure of a river (). Factors such as shape, cross-section and substrate, the extent of channel confinement, and the presence or absence of pools and riffles are all factors in the designation of a river style (). A geomorphological approach is appropriate for river management activities such as rehabilitation that ‘manipulate the physical structure of a river (its geomorphology) in attempts to improve water quality and enhance ecological values’ (Brierley et al., 2010), especially at local scales. However, for a regional-scale assessment it is not possible to model individual pools and riffles, nor is it possible to deal with the complexity of many tens of river styles. The focus of the is on changes to flow volumes and regimes, which logically suggests a more hydrologically-oriented classification such as the Australian National Aquatic Ecosystem (ANAE) Classification Framework (), in which rivers are classified firstly on flow regime and then on relevant aspects of landform (e.g. landscape position of riverbed substrate). The hydrological classification is important because it reflects the underlying water dependence of the different rivers.
A classification for rivers in the Gloucester was provided by The NSW Office of Water () that combined hydrological information with a key aspect of geomorphology: substrate. Substrate has a general relationship with river geomorphology. For example, bedrock confined streams are frequently high-energy upland streams while finer substrate streams and gravel or cobble substrate streams are frequently on lowlands (Boulton et al., 2014, p. 101). In the Gloucester PAE this classification scheme yielded seven in the riverine and one landscape class in the estuarine landscape group. This initial classification was further amalgamated to underpin the BA (Table 4). The NSW Office of Water classification identifies four ecohydrological classes, broadly based on : perennial (strong baseflow contribution), lowly intermittent (rarely cease to flow; moderate baseflow contribution), moderately intermittent (regularly cease to flow; dominated) and highly intermittent or ephemeral (rarely flow; runoff dominated). Only perennial and lowly intermittent streams are present in the Gloucester PAE and these are likely to have some dependence, whereas moderately and strongly intermittent streams are strongly (runoff) dependent.
Table 4 Landscape classes in the ‘Riverine’ and ‘Estuarine’ landscape groups derived from river types supplied by the NSW Office of Water for the Gloucester preliminary assessment extent
River reaches within the Gloucester PAE are dominated (47% of total stream length) by perennial streams with gravel or cobble substrate; these are mainly in the south of the PAE but also included the Gloucester River in the north. In the north of the PAE, intermittent streams with gravel or cobble substrate are more common. High-gradient perennial and intermittent streams with confined bedrock substrate comprise 21% of the total stream length and are located on the fringes of the PAE. Streams with fine substrate are uncommon (less than 6% of total stream length). For reference, the River Styles in Gloucester PAE are predominantly of the ‘Partly confined valley setting’ type (66%), with significant ‘Confined valley setting’ (21%) and ‘Laterally unconfined valley setting’ (12%).
Note that some river types have been amalgamated to create landscape classes in the riverine landscape group for convenience. The ‘Lowly intermittent flow, no pools – valley fill no pools’ river type deserves special mention. This river type comprises less than 1% of all streams in the and these have been combined with other river reaches with fine-textured substrate to create the ‘Intermittent – lowland fine streams’ landscape class in the riverine landscape group. ‘Valley fill’ river reaches are highly fragile and can be of great ecological significance when not degraded by catchment clearing and other land uses because this was the natural state of many small- and medium-sized streams (). In the area managed by the former Hunter-Central Rivers Catchment Management Authority (which entirely covers the Gloucester PAE), reaches with this geomorphology are frequently in poor condition as a result of livestock grazing (). This can result in loss of native vegetation, incision and transport of sediment downstream. Incision may lead to draining of alluvial present in these systems resulting in the of salt from surrounding sediments (). The high ecological significance of this river type lies primarily in its vegetation rather than its in-channel habitat (it typically contains no permanent pools) and its values are captured in the landscape classes in the ‘Groundwater-dependent ecosystem (GDE)’ landscape group (see Section 18.104.22.168.2.2). In addition to its very limited extent within the Gloucester PAE, it was determined that this was reason to combine it with another river type to construct a landscape class for the BA. In other where this river type is both more prevalent and contains very high ecological value such as upland swamps, it may be considered as a separate landscape class. The ‘Lowly intermittent flow, limited pools – entrenched’ river type comprised only 2% of the total stream length in the Gloucester PAE and is a degraded river type with little ecological value. It has a gravel or cobble substrate, resulting from channel instability, incision and sediment release (), possibly of former ‘Valley fill’ river reaches. For convenience it has been amalgamated with the dominant substrate type cobble/gravel.
Landscape classes in the riverine landscape group provide potential in-channel habitat for several species whose potential distributions form part of the register of (Bioregional Assessment Programme, ). These include fish and frogs (including the Stuttering and Giant Barred frogs, listed in the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)), and the community-nominated platypus, as well as freshwater oyster-growing regions of the Karuah River. Whilst the riverine landscape group is intended to capture in-channel habitats, rivers are necessarily connected to GDE vegetation that supports a range of terrestrial species, via the riparian zone. Hence, it is anticipated that of the riverine landscape group would include riparian vegetation elements and that there would be some overlap between riverine and some GDE conceptual models, although GDE vegetation is primarily dealt with through the ‘Groundwater-dependent ecosystem (GDE)’ landscape group (described in Section 22.214.171.124.2.1).
The NSW Office of Water methodology (Dabovic et al., in prep) defines as ‘which have their species composition and natural ecological processes wholly or partially determined by groundwater’. Dependence on can range from obligate to partial or infrequent () but excludes species that rely exclusively on soil water in the vadose zone. The classification of mapped GDEs is based on which adopts Keith’s (2004) classification of vegetation communities into ‘formations’ and ‘classes’.
‘Vegetation formation’ is the top level of the hierarchy in Keith’s vegetation classification system. Formations represent broad groups distinguished primarily by structural and physiognomic features, with the addition of functional features such as salinity and drought tolerance in some cases (). Of the twelve vegetation formations used across NSW, six have been identified in the Gloucester (Table 4), and all were identified in the GDE mapping. The areas of each within the PAE, along with their names, are given in Table 6.
Table 5 Description of Keith’s (2004) vegetation formations
The ‘Saline wetlands’ landscape class accounted for 35% of the GDE area within the PAE and is restricted to the far south of the PAE along with ‘Freshwater wetlands’ landscape class (Table 7); the latter accounts for only 7% of GDEs in the PAE. ‘Forested wetlands’ landscape class accounts for the majority of non-estuarine GDEs in the Gloucester PAE (33%; Table 6) and are overwhelmingly in the ‘Coastal floodplain wetland’ Keith vegetation class. The ‘Rainforests’ landscape class is overwhelmingly composed of the ‘Northern warm temperate rainforests’ Keith vegetation class (Table 6). The ‘Subtropical rainforests’ Keith vegetation class includes ‘Lowland Subtropical Rainforest on Basalt Alluvium in NE NSW and SE Qld’, a threatened ecological community listed in the register of (Bioregional Assessment Programme, ), makes up a very small fraction of all the ‘Rainforests’ landscape class. Rainforests are also predominantly in the southern part of the PAE. Similarly the ‘Dry sclerophyll forests’ landscape class is concentrated in the southern part of the PAE; this landscape class is dominated by the ‘Hunter-Macleay dry sclerophyll forests’ Keith vegetation class. The ‘Wet sclerophyll forests’ landscape class has a very scattered distribution and is mainly in the north of the PAE; this landscape class is overwhelmingly dominated by the ‘North Coast wet sclerophyll forests’ Keith vegetation class. Only forested wetlands and rainforests occur above the alluvium to any significant extent. All other GDE types occur away from the alluvium.
Table 6 Area of landscape classes in the ‘Groundwater-dependent ecosystem (GDE)’ landscape group, and the ‘Estuarine – saline wetlands’ landscape class, within the preliminary assessment extent of the Gloucester subregion
PAE = preliminary assessment extent
The PAE of the Gloucester subregion covers 46,820 ha.
aKeith’s (2004) classification of vegetation communities into ‘formations’ and ‘classes’
GDEs provide habitat for many of the species whose potential distributions form part of the register of water-dependent assets (Bioregional Assessment Programme, ). For example, animals such as koalas, birds of prey, honeyeaters and flying foxes may live, roost or nest in trees within GDEs. Some state and nationally listed plant species, such as the leafless tongue orchid, may be associated with GDE vegetation. GDEs along river banks (i.e. riparian vegetation) provide travel corridors and feeding sites for animals such as quolls, ground nesting locations for animals such as platypus, and breeding locations for some frogs. Riparian vegetation affects both the physical and chemical properties of river channel habitats by providing shade, as well as large woody debris and fine litter. This provides in-channel habitats as well as energy for instream biota, and can maintain or alter stream geomorphology.
The nature of groundwater and/or dependence of much GDE vegetation is uncertain. GDEs may occur at any position in the landscape where factors such as topography, geology and landform allow groundwater to concentrate at the surface or close enough to the surface for phreatophytic vegetation to access (). The dependence of terrestrial vegetation on groundwater is difficult to predict or quantify (). Riparian and near-riparian vegetation may have an absolute dependency on groundwater (obligate phreatophyte) while vegetation further from surface expression of groundwater, where depth to groundwater is greater, may make occasional use of groundwater (facultative phreatophyte). Other vegetation may utilise local groundwater sources such as local (perched) . It is possible for a vegetation community to have more than a single water dependence; for example, individuals within a community may require flooding events for seedling recruitment and survival during early life stages, but be reliant on groundwater in later life stages. Groundwater levels would be likely to fluctuate naturally as a result of climate variability, and the vegetation is likely adapted to deal with this. However, rapid, large changes to groundwater levels resulting from abstraction have been shown to result in morbidity and death of GDE vegetation ().
The following water dependencies associated with landscape classes were identified:
- Local rainfall. These vegetation communities are dependent on local rainfall only and will not be affected by abstraction of regional groundwater or changed surface water flows, but could be impacted by local development such as clearing associated with CSG and/or coal mine establishment and operation.
- Local groundwater. These vegetation communities may rely on local that are unconnected to regional groundwater aquifers (e.g. perched aquifers above rock). They will also not be affected by abstraction of regional groundwater or changed surface water flows, yet could be impacted by local development such as open-cut mining (depending on distance between the operation and the vegetation community and hydrological transmittance of the alluvial system).
- Surface water. These vegetation communities are dependent on surface flows from flooding events for their maintenance.
- Regional groundwater. These vegetation communities rely on water from regional groundwater aquifers for their productivity and survival at least occasionally. Some may be dependent on access to groundwater at all times. Some may be able to survive or adjust to removal of groundwater, depending on the rate of abstraction, but their current structure and floristic composition may be altered as a result.
- Tidal. Estuarine communities are sensitive to tidal flows in addition to groundwater and surface water flows. They can be impacted by changes in geomorphology of the estuary and patterns of sedimentation that might result from altered surface water flows, and by changes in salinity in upper estuarine reaches in situations of altered fresh surface water and groundwater .
The water dependencies of the Keith vegetation formations and associated Keith vegetation classes in the Gloucester PAE are presented in Table 7. These are based on general information about the location of the classes within the landscape, their characteristics and associated species from Keith (2004), lists of known GDEs and expert advice from the NSW OEH. Although some vegetation formations have been judged as unlikely to be water dependent for the purposes of the BA, they are nonetheless present in the NSW Office of Water mapping of GDEs (NSW Department of Primary Industries, ). This reflects the large associated with the remote classification of both vegetation formations () and groundwater dependency () (discussed in Section 126.96.36.199.3). This is a key reason why vegetation formation, rather than vegetation class, was adopted as the landscape class for the BA. GDEs in landscape classes that are potentially impacted by development will have more detailed developed as part of receptor impact modelling (see companion product 2.7 (receptor impact modelling) for the ). Where a landscape class contains Keith vegetation classes that are heterogeneous with regard to their water dependencies (e.g. ‘Coastal swamp forests’ Keith vegetation class and ‘Eastern riverine forests’ Keith vegetation class within the ‘Forested wetlands’ landscape class) it may be necessary to develop more than one detailed receptor impact model for that landscape class within a region. In the Gloucester subregion, the ‘Forested wetlands’ landscape class is represented almost exclusively by the ‘Coastal floodplain wetlands’ Keith vegetation class.
Table 7 Water dependence of landscape classes in the ‘Groundwater-dependent ecosystem (GDE)’ landscape group and the ‘Estuarine – saline wetlands’ landscape class and their associated Keith (2004) vegetation classes
aKeith’s (2004) classification of vegetation communities into ‘formations’ and ‘classes’
188.8.131.52.2.3 Landscape classes in the ‘Estuarine’ landscape group
The estuarine reaches of the Karuah River are classified as ‘Barrier river’ (Table 4), consistent with the classification system used by the NSW OEH (). As described in Section 184.108.40.206.2.2 for , the ‘Saline wetlands’ landscape class (Table 5) is defined based on mapping of GDEs to Keith’s (2004) vegetation formations. Saline wetlands are all in the estuarine reaches of the Karuah River and are mainly mangroves with some saltmarshes (Table 6). Saline wetlands are habitats for animals such as waterbirds and migratory birds, as well as fish and a diverse assemblage of invertebrates. Reduced freshwater pulses and flooding, and abstraction, may impact on a variety of freshwater habitats and in-channel biological processes, and result in the spread of saline wetlands further upstream.
220.127.116.11.2.4 Landscape classes in the ‘Non-GDE’ landscape group
Over 13,000 ha of native vegetation within the Gloucester is not classified as . All the native vegetation outside that mapped in the riverine, GDE and estuarine is considered not to be dependent on surface or . Of this 13,000 ha, over 10,000 ha was classified as dry sclerophyll forest or wet sclerophyll forest. A further 1500 ha was classified as rainforest, 1700 ha classified as forested wetland, and 118 ha classified as saline wetland. No native vegetation was classified as freshwater wetland. The fact that the 1700 ha of native vegetation classified as forested wetland was not classified as GDE reflects the large (see Section 18.104.22.168.3) associated with the remote classification of both vegetation formation () and groundwater dependency ().
22.214.171.124.2.5 Landscape classes in the ‘Economic land use’ landscape group
Over 31,000 ha of the Gloucester did not overlap with any of the defined in Section 126.96.36.199.2.1, Section 188.8.131.52.2.2 and Section 184.108.40.206.2.4. These areas were classified using ‘ALUM’ (for catchment-scale land use management classification in Australia), Update 14 (ABARES-BRS, ) as follows:
- Plantation or production forestry. This corresponds to ALUM classes 2.1 (Grazing native vegetation), 2.2 (Production forestry), 3.1 (Plantation forestry) and 4.1 (Irrigated plantation forestry).
- Dryland agriculture. This corresponds to ALUM classes 3.2 (Grazing modified pastures), 3.3 (Cropping), 3.4 (Perennial horticulture), 3.5 (Seasonal horticulture) and 3.6 (Land in transition).
- Irrigated agriculture. This corresponds to ALUM classes 4.2 (Grazing irrigated modified pastures), 4.3 (Irrigated cropping), 4.4 (Irrigated perennial horticulture), 4.5 (Irrigated seasonal horticulture) and 4.6 (Irrigated land in transition).
- Intensive uses. Land is subject to substantial modification, generally in association with closer residential settlement, commercial or industrial uses. This class includes mining.
- Water. Mainly reservoirs and dams.
Most (nearly 28,000 ha) of the remaining unclassified area is classified as ‘Dryland agriculture ’. Nearly 2000 ha is classified as ‘Intensive uses’ (mainly urban and mining) and nearly 1000 ha is classified as ‘Water’ (reservoirs, etc.).
Bioregional assessments seek to use the best available data, given licensing and other constraints. However, even the best available data have significant constraints. The Greater Hunter mapping of vegetation (CSIRO Land and Water, ) on which the mapping of is based (NSW Department of Primary Industries, ) is a good example. A recent ground-truth study in the Upper Hunter () found that only 7% of plant community types (PCTs) were reliably mapped. Even at the level of vegetation formation only dry sclerophyll forests and woodlands were mapped with greater than 50% accuracy. On this basis, the were not defined at detailed hierarchical levels such as vegetation class or PCT. Even at the level of vegetation formation there is great and this would have been exacerbated by attempting to deal with landscape classes at even more detailed levels.
This uncertainty adds to the overall uncertainty regarding the impact, if any, of developments on such as potential habitats of threatened or endangered species and communities. Assigning such assets to landscape classes is necessarily highly uncertain due to both the high hierarchical level of the landscape classes (a species might use some vegetation within a formation as habitat but not others) and the uncertainty as to whether the vegetation formation is, in fact, present where it has been mapped. All of this is in addition to the uncertainty already associated with the potential habitat modelling undertaken by the Environmental Resources Information Network (ERIN). ERIN utilises maximum entropy (MAXENT) modelling to define the geographic extent of potential habitats based largely on physical parameters and past observations of the presence and absence of a species (). The results of this modelling may predict potential habitat in areas where the that support such species may not be present. Where the ecosystem, and thus the ‘potential’ habitat, is present the species itself may not be present due to many other factors, such as predation and habitat fragmentation.
There will also be great uncertainty associated with any predicted impacts on landscape classes in the ‘Riverine’ . In addition to the simplified landscape classification adopted for the BA, it is also important to note that for the purposes of a BA for that can be tens and hundreds of thousands of hectares, it is not possible to model riverine systems at the scale of pools and riffles. Even the ‘reach’ scale (1–3 km river lengths) used within River Styles is already quite detailed for a regional-scale analysis. Individual hillslope processes are not being quantitatively modelled. As mentioned in Section 220.127.116.11.2, changes in geomorphology that might result from development or remedial activities to improve geomorphology of degraded river sections are not within scope of the BA. This would require detailed cross-sections for river reaches in proximity to development and remediation activities and more detailed modelling than is possible within the current round of the BA. Where developments have the potential to create local-scale impacts, the acquisition of detailed riverbed cross-sections and monitoring of both geomorphology and key biological indicators such as macro-invertebrates, diatoms and water quality (Boulton et al., 2014, p.276) should occur to track and assess such local impacts.
Product Finalisation date
- 2.3.1 Methods
- 2.3.2 Summary of key system components, processes and interactions
- 2.3.3 Ecosystems
- 2.3.4 Baseline and coal resource development pathway
- 2.3.5 Conceptual modelling of causal pathways
- Currency of scientific results
- Contributors to the Technical Programme
- About this technical product