3.5.1 Overview

This section describes the risks to ecological, economic and sociocultural assets that are potentially impacted by hydrological changes arising in response to future pathways of coal mining and coal seam gas (CSG) development in the Galilee subregion. Potential impacts on and risks to water-dependent assets as a consequence of additional coal resource development were assessed using a variety of approaches. These were:

Overlay analysis can identify assets that are unlikely to be impacted by surface water or groundwater changes, based on the lack of intersection with the zone of potential hydrological change.

As described in companion product 2.7 for the Galilee subregion (Ickowicz et al., 2018), receptor impact models were developed for two landscape groups (‘Floodplain, terrestrial GDE’ and ‘Non-floodplain, terrestrial GDE’) and a combination of an additional two landscape groups (i.e. the ‘Streams, GDE’ and ‘Streams, non-GDE’ landscape groups were combined to form the ‘Streams’ supergroup). Each landscape group consists of a number of landscape classes as described in companion product 2.3 for the Galilee subregion (Evans et al., 2018b). Qualitative mathematical models were developed for each of the three landscape groups/supergroups identified above. In addition, a qualitative mathematical model was developed for the ‘Springs’ landscape group (refer to Table 19 in Section 3.4).

Overlay analysis was used to identify assets that are very unlikely to be impacted by surface water or groundwater changes due to additional coal resource development, based on lack of intersection of the asset with the zone of potential hydrological change. The zone of potential hydrological change for the Galilee subregion is defined in Section 3.3 . The impact and risk analysis uses different probabilities (5th, 50th (median) and 95th percentiles) to indicate the likelihood of hydrological changes to different types of water-dependent assets in the zone of potential hydrological change. The 5th percentile identifies the magnitude of hydrological change that is very likely (greater than 95% chance); the 95th percentile defines the magnitude of hydrological change (though not necessarily ecological impact) that is very unlikely (less than 5% chance).

The analysis of impacts and risks considers each group of water-dependent assets separately – ecological, economic and sociocultural. Each subgroup of ecological assets is also described separately – ‘Surface water feature’, ‘Groundwater feature (subsurface)’ and ‘Vegetation’. To improve clarity, assets in the ‘Surface water feature’ and ‘Vegetation’ subgroups are further divided into classes. Assets in the ‘Surface water feature’ subgroup are divided into six classes and those in the ‘Vegetation’ subgroup are divided into three classes (Table 30).

Economic assets are separated into two classes: ‘Groundwater management zone or area (surface area)’ and ‘Surface water management zone or area (surface area)’. Potential hydrological changes to all groundwater bores (as listed in the Queensland bore database) in the zone of potential hydrological change that are not included as part of the water-dependent asset register are also considered.

The intersection of sociocultural assets with the zone of potential hydrological change is then described, and potential for impact assessed.

The broad spatial extent and considerable number of water-dependent assets mean that not all assets are mapped and assessed in this section. Instead the focus is on a subset of the assets, which are deemed to be ‘more at risk of hydrological changes’ (i.e. those assets associated with higher probabilities of larger hydrological changes). However, in Section 3.5.2.7 a case study is provided to illustrate the type of detailed analysis that is possible for individual assets, based on the integration of multiple lines of available hydrological and ecological evidence. The specific asset example focuses on the ‘potential distribution of Black Ironbox’ (BA asset identification number 2126 in the water-dependent asset register), which occurs in the northern part of the surface water zone of potential hydrological change and is associated with reaches of the Suttor River upstream of Lake Dalrymple.

The impact and risk analysis uses a combination of summary tables, maps of modelled hydrological change within assets, plots of cumulative asset extent and degree of modelled hydrological change and narrative. The spatial extent and number of water-dependent assets mean that not all assets can be mapped and assessed in this product. Potential impacts to individual assets can be visually explored at www.bioregionalassessments.gov.au/explorer/GAL/assets.

Importantly, it should be noted that asset information, such as the potential distribution of species and communities, was not updated during the course of this BA. Rather, the potential species distributions were used for BA purposes as they were known (i.e. as mapped) at a particular point in time, which was current at the time when the modelling was started for this BA. However, any subsequent changes in mapped distributions as a result of later field studies or further analysis have not been incorporated into the findings of this Assessment.

Finally, this section describes impacts on and risks to assets due to potential hydrological changes for only that part of the coal resource development pathway (CRDP) that was able to be modelled (i.e. the seven proposed coal mines in the central-eastern Galilee subregion, as described in Section 3.3). Section 3.6 provides commentary for that part of the CRDP that was not modelled.