3.7.3 Using this impact and risk analysis

Findings from the BA of the Galilee subregion can help governments, industry and the community provide better-informed regulatory water management and planning decisions. Assessment results flag where future efforts of regulators and proponents can be directed, and where further attention is not necessary. The zone of potential hydrological change is the area where the magnitude of the hydrological changes due to additional coal resource development suggests that impacts to water-dependent ecosystems and assets are possible, particularly for those that rely on access to surface water or relatively shallow groundwater systems. Outside of this zone, adverse impacts on most water-dependent ecosystems and assets due to additional coal resource development are considered very unlikely. However, it is important to also consider potential impacts to any ecosystems or assets that may access groundwater sourced from deeper (confined) aquifers, as these may require further evaluation using modelling results that are specific to such deeper hydrostratigraphic layers.

This assessment identified a suite of potential coal mining and CSG developments that defined the CRDP for the Galilee subregion (as reported in companion product 2.3 for the Galilee subregion (Evans et al., 2018)). However, the main focus of the impact and risk analysis reported here, especially the quantitative analysis of hydrological and ecological impacts, is on the seven coal mines that could be included in the BA numerical modelling. The zone of potential hydrological change is based exclusively on the results from this probabilistic hydrological modelling, and does not incorporate the other seven potential mines and three CSG fields that are part of the CRDP (as discussed in Section 3.6). The limited amount of information for these less-advanced development projects at the start of the BA modelling meant that it was only possible to qualitatively assess potential impacts of these non-modelled components of the CRDP. Consequently, it is important that users of this impact and risk analysis understand this limitation of the assessment, and that most results presented here are constrained to the part of the Galilee subregion where future coal mining development is most likely to start. However, as there are seven other mining operations and three CSG developments that were not modelled for this BA, any future updates to the BA modelling suite (i.e. that were able to include any of these other developments) would likely increase the spatial extent of the zone of potential hydrological change, thereby potentially meaning that future updates to the impact and risk analysis could incorporate other water-dependent assets and landscape classes.

This Assessment predicts the likelihood of exceeding levels of potential hydrological change at a regional level. It also provides important context to identify potential issues that may need to be addressed in local-scale environmental impact assessments of new coal resource developments. It should help project proponents to meet legislative requirements to describe the environmental values that may be affected by the exercise of underground water rights, and to adopt strategies to avoid, mitigate or manage these predicted impacts. This Assessment does not investigate the broader social, economic or human health impacts of coal resource development, nor does it consider risks of fugitive gases and non-water-related impacts.

BAs are not a substitute for careful assessment of proposed coal mine or coal seam gas (CSG) extraction projects under Australian or state environmental law. Such assessments may use finer-scale groundwater and surface water models and consider impacts on matters other than water resources. However, the Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development (a federal government statutory authority established in 2012 under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999) can use these Assessment results to help formulate their advice on specific coal resource development proposals.

BAs have been developed with the ability to be updated, for example, to incorporate new coal resource developments in the hydrological modelling. This is particularly important for the Galilee subregion, given that only half of the mines (and no CSG fields) in the CRDP were included in the modelled assessment presented here. Existing datasets, such as the water-dependent asset register, remain relevant for future assessments. If new coal resource developments emerge in the future, the data, information, analytical results and models from this Assessment would provide a comprehensive basis for subregion-scale re‑assessment of potential impacts under an updated CRDP. It may also be applicable for other types of land use or resource developments (e.g. agricultural developments or other types of mining operations) that can potentially affect water resources and associated assets.

The full suite of information, including information for individual assets, is provided at www.bioregionalassessments.gov.au with more detailed results available using the online BA Explorer tool for:

Other related investigations that inform the BA of the Galilee subregion include the Lake Eyre Basin Rivers Assessment (LEBRA) and Lake Eyre Basin Springs Assessment (LEBSA). The LEBSA and LEBRA programmes encompass a number of complementary projects funded by the Department of the Environment and Energy. Of particular relevance to the Galilee subregion is the work of Fensham et al. (2016), which reported on the hydrogeology, history and biological values of many spring groups in central and western Queensland, including the three spring clusters that occur within the zone of potential hydrological change for the Galilee subregion. Other reports and data for the LEBRA and LEBSA projects will be released at www.bioregionalassessments.gov.au in the near future.

The Galilee Basin hydrogeological (GBH) model is a regional-scale numerical groundwater flow model (built using the industry standard MODFLOW code) developed utilising data and interpretations compiled to support the BA of the Galilee subregion. This model incorporates hydrogeological and geological information for both the Galilee Basin and the overlying Eromanga Basin. The model was jointly funded by the Department of the Environment and Energy, and the Queensland Government, and involved collaboration with the Assessment team charged with undertaking the BA of the Galilee subregion. A consultant firm – HydroSimulations – was engaged to produce a calibrated and stress-tested transient numerical groundwater flow model capable of simulating the cumulative impacts of proposed coal mining developments in the central-eastern Galilee Basin. The detailed GBH model report (Turvey et al., 2015) and associated model files are available at www.bioregionalassessments.gov.au. Companion product 2.6.2 for the Galilee subregion (Peeters et al., 2018) provides an overview of the GBH model as well as a summary of its strengths and current limitations. The GBH model provides a more sophisticated representation of the hydrostratigraphy of the Galilee and Eromanga basins, and could provide the basis for any future cumulative impact assessments, building upon the initial work undertaken for this BA.

Access to underpinning datasets, including shapefiles of geographic data and modelling results, can assist decision makers at all levels to review the BA work undertaken to date; to explore the results using different thresholds for the various hydrological response variables; and to extend or update the assessment if new models, data or mine or CSG development plans become available. Additional guidance about how to apply the Programme’s overarching methodology is also documented in a detailed series of scientific submethodologies (Table 1), covering everything from surface water and groundwater modelling to developing the CRDP and undertaking the impact and risk analysis.

Lastly, the Programme’s rigorous commitment to data access is consistent with the Australian Government's principles of providing publicly accessible, transparent and responsibly managed public-sector information.

Last updated:
6 December 2018
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