Bioregional assessment methodology

Executive summary

The Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development (IESC) has been established under the Environment Protection and Biodiversity Conservation Amendment (Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development) Bill 2012 to provide advice to the Federal Minister for the Environment on potential water-related impacts of coal seam gas (CSG) and large coal mining developments.


Bioregional assessments (BAs) are one of the key mechanisms to assist the IESC in developing this advice so that it is based on best available science and independent expert knowledge. A BA is a scientific analysis, providing a baseline level of information on the ecology, hydrology, geology and hydrogeology of a bioregion with explicit assessment of the potential direct, indirect and cumulative impacts of CSG and coal mining development on water resources.

The present document (the BA methodology or BRAM) is intended to articulate the scientific and intellectual basis for a consistent approach to all BAs. This methodology provides guidance to research scientists and managers preparing BAs within research agencies that have been charged with the task of researching and preparing BAs to provide advice on impacts.

The purpose of a BA is to:

  • Define, characterise and explain conceptual models that establish causal pathways describing the chain of interactions and events connecting depressurisation and dewatering of coal seams at depth with impacts on anthropogenic and ecological receptors located at depth or the surface.
  • Generate quantitative, semi-quantitative or qualitative analyses of the likelihood of impacts of CSG and coal mining developments on receptors from the application of ecology, surface water and groundwater hydrology, hydrogeology and CSG or coal resource development models.
  • Develop improved assessments of the likelihood of risks to receptors and the subsequent values of water-dependent assets from CSG and coal mining developments.
  • Provide information on the level of confidence of scientific advice on these impacts.
  • Identify monitoring programs, BA review frequency and additional risk assessment studies that could be undertaken outside of the bioregional assessment process to help minimise impacts of CSG and coal mining developments on water resources.

A BA is conducted within a specified area termed a 'bioregion'. The bioregion itself contains identified key water-dependent 'assets' within which are located 'receptors'. A water-dependent asset is an entity, such as a Ramsar or state significant wetland, within a bioregion with characteristics having value and which can be linked directly or indirectly to a dependency on water quantity or quality. Receptors are discrete, identifiable attributes, such as a particular rare or threatened species, contained within assets that are measurably impacted by a change in water quantity or quality resulting from CSG or coal mining development. It is through receptors that the impacts of CSG and coal mining development are defined within a BA. These impacts include changes in baseline variables, flow regimes, hydraulic conditions, surface water – groundwater connections, inundation patterns and effects of salt or salinity. Other impacts such as ecotoxicology, human health or water quality impacts, from heavy metal contamination or impacts of hydraulic fracturing fluids are being considered by other research and studies (such as the 'National Assessment of Chemicals associated with coal seam gas extraction') and will be able to be linked to the BAs. From these impacts on receptors, positive or negative effects of CSG and coal mining development on the values of assets can be determined. While a BA provides advice on the receptors and assets, it does not analyse the economic or social impacts and risks of CSG and coal mining development. The information from a BA will provide a regional context for providing advice for decision makers. However, it is not a development-specific environmental impacts assessment. At the same time, BAs will undoubtedly inform development-specific assessments.

A BA comprises five components of activity:

  • Contextual information: Component 1 presents the context and background against which qualitative and quantitative assessments of impact and risk of CSG and coal mining development are generated.
  • Model-data analysis: Component 2 evaluates and synthesises information from data and models to develop a quantitative description of the hydrologic relationship between coal seam depressurisation and dewatering and associated impacts on anthropogenic or ecological receptors.
  • Impact analysis: Component 3 reports and records the direct, indirect and cumulative impacts and associated uncertainties of impacts of CSG and coal mining development on receptors within assets and their associated uncertainties.
  • Risk analysis: Component 4 provides a scientific assessment of the likelihood of impacts on receptors contained within assets based on the propagation of uncertainties from models and data.
  • Outcome summary: Component 5 delivers a summary of outcomes used by the IESC to support scientific advice on impacts and risk of CSG and coal mining development on water resources.

These five components guide and organise the overall BA. A key element to any bioregional assessment is the development of baseline information so that impacts can be assessed against the current state of the region. The key baseline information requirements are outlined in this document. Information generated during the contextual information and model-data analysis components accumulates to provide knowledge used in the impact analysis and risk analysis components. The impacts and risks are focused through the receptors contained within water-dependent assets (as described above). The components are not sequential in time; rather they are largely overlapping, and information passes between components of the BA via multidisciplinary interactions. In this way groundwater and hydrogeology information on dewatering at depth can inform ecological impacts on receptors at the surface. A key aspect of a BA is the characterisation and propagation of uncertainties in order to provide scientific advice on the likelihood of impacts on receptors and their associated risks.

Specific workflows will vary between BAs in response to the availability of existing data, information and fit-for-purpose models. The products derived from a BA are subject to review and updates to ensure they provide an enduring source of scientific information with which to frame ongoing advice to the Minister.

While a BA ideally is a quantitative analysis of impacts, it is recognised that data, information and model deficiencies may preclude this. In this case, semi-quantitative and qualitative methods are to be substituted – supported by multiple lines of evidence – to provide the best and most current scientific advice possible to date on the impacts of dewatering on receptors and water-dependent assets.

Where decisions are made in the exercising of the BRAM within a bioregion or subregion and scientific judgment must be exercised, the resulting decisions must be recorded in the workflows and made transparent. In each case, measures of confidence are required to be provided in the scientific advice. As such, the BA provides a defensible baseline statement as to the current state of scientific knowledge on the impacts of CSG and coal mining development on water resources within a bioregion and its subregions.

Last updated:
7 March 2017