The impact and risk analysis followed the overarching methodology described in companion submethodology M10 (as listed in Table 1) for analysing impacts and risks (Henderson et al., 2017). The impact analysis quantified the magnitude or extent of the potential hydrological or ecosystem changes due to coal resource development, including direct, indirect and cumulative. The risk analysis considered not only the magnitude or extent of the potential impact, but also the likelihood of the impact.
The first step in the impact and risk analysis was to use the conceptual model of causal pathways and probabilistic estimates of hydrological change to identify potential impacts to water-dependent landscapes and assets. Impacts to water-dependent landscapes and assets are mostly caused by changes to groundwater in the regional watertable.
For bioregional assessment (BA) purposes, the regional watertable represents the upper groundwater level within the near-surface aquifer (not perched), and may exist in different geological units or layers. Near the two additional coal resource developments it occurs in the alluvium, as well as the Main Range Volcanics and the Walloon Coal Measures. Springs and groundwater bores may be affected by hydrological changes in deeper geological layers, which may have repercussions for surface ecosystems surrounding springs.
The adapted Office of Groundwater Impact Assessment (OGIA) model was used to quantify hydrological changes to the groundwater system arising from coal resource development in the subregion. Estimates of groundwater drawdown for the two futures considered by BAs were used to define a zone of potential hydrological change for each potentially affected model layer or source aquifer.
Potential impacts to water-dependent landscapes and assets were assessed by overlaying their location on the zone of potential hydrological change for the relevant source aquifer. Outside this zone, landscapes and assets were ruled out from potential impacts and not analysed further. Inside the zone, potential hydrological changes were summarised for each landscape class or asset. The databases, tools and geoprocessing that support the impact and risk analysis were also summarised.
Product Finalisation date
- 3.1 Overview
- 3.1.1 Maranoa-Balonne-Condamine subregion
- 3.1.2 Scope and context
- 3.1.3 Structure of this product
- 3.2 Methods
- 3.2.1 Impact and risk analysis
- 3.2.2 Causal pathways
- 3.2.3 Hydrological analysis
- 3.2.4 Assessing potential impacts for landscape classes and assets
- 3.3 Potential hydrological changes
- 3.3.1 Defining the zone of potential hydrological change
- 3.3.2 Potential groundwater changes
- 3.3.3 Potential surface water changes
- 3.3.4 Potential water quality changes
- 3.4 Impacts on and risks to landscape classes
- 3.4.1 Overview
- 3.4.2 Landscape classes that are unlikely to be impacted
- 3.4.3 'Floodplain or lowland riverine (including non-GAB GDEs)' landscape group
- 3.4.4 'GAB GDEs (riverine, springs, floodplain or non-floodplain)' landscape group
- 3.4.5 'Non-floodplain or upland riverine (including non-GAB GDEs)' landscape group
- 3.4.6 'Human-modified' landscape group
- 3.5 Impacts on and risks to water-dependent assets
- 3.6 Commentary for coal resource developments that are not modelled
- 3.7 Conclusion
- 3.7.1 Key findings
- 3.7.2 How to use this impact and risk analysis
- 3.7.3 Gaps, limitations and opportunities
- Contributors to the Technical Programme
- About this technical product