Drawdown in the regional watertable under the baseline has a greater than 5% chance of exceeding 0.2 m in an area of 17,132 km2 where the deeper geological layers outcrop at the surface. Median baseline drawdown in the regional watertable is typically less than 20 m; it is less than 3 m in the vicinity of New Acland Coal Mine and less than 8.3 m in the vicinity of The Range coal mine.
Additional drawdown in the regional watertable has a greater than 5% chance of exceeding 0.2 m in an area of 1631 km2. Subsequently, the extent in the zone of potential hydrological change is reported as 1544 km2, which includes 1095 km of streams and excludes the 87 km2 within the modelled open-cut mine pits that are not included in the analysis. Additional drawdown occurs within 15 km of New Acland Coal Mine Stage 3 and within 25 km of The Range coal mine. The regional watertable is in the alluvium, as well as the Main Range Volcanics, the Walloon Coal Measures and the Hutton/Marburg Sandstone geological layers near the two additional coal resource developments.
In the vicinity of New Acland Coal Mine, additional coal resource development is predicted to lower the regional watertable by at least an additional 0.2 m over an area of between 7 km2 including 4 km of streams (5th percentile) and 134 km2 including 55 km of streams (95th percentile). Additional drawdown in the regional watertable near The Range coal mine is predicted to lower the regional watertable by at least an additional 0.2 m over an area of between 377 km2 including 231 km of streams (5th percentile) and 1409 km2 including 1040 km of streams (95th percentile).
Potential risks to groundwater and surface water quality are localised within tenements; downstream watercourses and alluvial aquifers; and irrigated areas or target aquifers used to dispose of co-produced water, which are addressed by existing regulation and management practices.
Users can visualise more detailed results for hydrological changes using a map-based interface on the BA Explorer, available at www.bioregionalassessments.gov.au/explorer/MBC/hydrologicalchanges.
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