1 Introduction

1.1 Background

This document presents the bioregional assessment methodology (BA methodology or BRAM) agreed by the Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development (IESC). It is intended to set the scientific and intellectual basis upon which a consistent approach to all bioregional assessments (BAs) can be undertaken, to assist decision making in relation to the water-related impacts of coal seam gas (CSG) and coal mining.

The BA methodology provides the scientific basis or the 'how to' undertake bioregional assessments which addresses one of the requirements of the IESC under the Environment Protection and Biodiversity Conservation Amendment (Independent Expert Scientific Committee on Coal Seam Gas and Large Coal Mining Development) Act 2012.

From a scientific perspective, the BA methodology records the process to collect and present bioregional information; to determine the direct, indirect and cumulative impacts of CSG and coal mining development on water resources; and to estimate the risks to anthropogenic and ecological receptors that arise from such impacts.

The BA methodology is not intended to be a customised blueprint or 'recipe book' for exact specification of a BA in any particular bioregion or sub-region, as each bioregion or sub-region will differ in data availability and physical characteristics. However, the BA methodology has a generic role in guiding and enabling consistency and rigour in each assessment despite differences among bioregions or sub-regions. The BA methodology is written for science researchers within agencies that are charged with the task of undertaking a BA.

1.2 Purpose

The BA methodology is the underpinning scientific approach to – and guidance on – conducting BAs, which will provide an information source for the IESC in preparing its advice to the Minister and regulators on project proposals and research priorities.

The role of the IESC is to provide scientific advice on the likelihood of significant impacts of proposed CSG and large coal mining developments on water resources (including impacts of associated salt production and/or salinity). The IESC endorses risk-based approaches to advising on the impacts of proposed developments on the values of water-dependent assets.

A BA, as defined in the National Partnership Agreement, is a scientific analysis of 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 IESC was established under the Commonwealth's Environment Protection and Biodiversity Conservation Amendment Act (2012) to:

  • improve the science base in relation to the interaction of CSG and large coal mining developments and water resources
  • provide Commonwealth, state and territory governments with expert scientific advice relating to CSG and large coal mining development proposals likely to have a significant impact on water resources.

Within a BA, data and information are assembled for formulating expert scientific advice on specific bioregions.

The central purpose of BAs is to analyse the impacts and risks associated with changes to water-dependent assets that arise in response to current and future pathways of CSG and coal mining development.

Outputs from a BA consist of:

  • scientific advice on the likelihood of direct, indirect and cumulative impacts on anthropogenic and ecological receptors contained within water-dependent assets
  • conceptual modelling of the causal pathway establishing the chain of interactions connecting depressurisation and dewatering of coal seams at depth with impacts on receptors located at or near the surface
  • quantitative, semi-quantitative and qualitative results from relevant ecological, surface water hydrology, groundwater, hydrogeology and CSG or coal mining development models that provide information on the extent and nature of impacts in response to pathways of CSG and coal mining developments
  • measures of confidence in the advice regarding impacts on receptors
  • advice on the likelihood of risks to receptors and water-dependent assets under CSG and coal mining development pathways – and the potential consequences
  • information on monitoring programs, the frequency of future BA reviews, the nature and type of additional risk assessment studies that may be required, and possible approaches to risk mitigation for minimising significant impacts.

It is not possible to define a prescriptive process that would produce a BA for any given bioregion when followed step by step, due to the differences in data, geology, hydrogeology and ecology across regions, as well as differing CSG and coal resource development pathways:

  • the highly multidisciplinary and integrative nature of a BA
  • the plethora of different philosophies, methods and languages used in each of the disciplines
  • the technical details of specific measurement and modelling methods undertaken.

Instead of a prescriptive process, this document specifies an overarching principle to the generation of BAs. Where departures from this principle occur (due to deficiencies in data, information and models), these are recorded, judgments exercised on what can be achieved, and an explicit record is made of the confidence in the scientific advice produced from the BA.

The principle underpinning a BA is as follows:

The methodology must be, to the extent possible, a quantitative analysis of the impacts of dewatering and depressurisation of coal seams on surface or near-surface receptors contained within water-dependent assets located within a bioregion. The applied methodology will use coupled models for hydrogeology, surface hydrology, and impacts (both anthropogenic and ecological). The modelling will be constrained by groundwater and surface water observations and incorporate a quantitative assessment and propagation of statistical uncertainties from the event (dewatering and depressurisation) to location of impact (anthropogenic and ecological receptors). Where quantitative methods are not feasible (due to knowledge deficiencies), semi-quantitative and qualitative methods will be substituted, supported by multiple lines of evidence to provide scientific advice on the impacts and risks to assets and receptors. Where decisions are made and scientific judgment exercised, these decisions and judgments will be recorded and made transparent in the reporting process. A bioregional assessment will provide scientific advice on the likelihood of direct, indirect and cumulative impacts of the event on receptors and identify and quantify associated risks to the value of water-dependent assets.

In this way, the BA builds a compendium of knowledge across multiple disciplines that begins with the best scientific information available at the present time; includes what is known and what is not known about the impacts of CSG and coal mining development on water-dependent assets; and provides a pathway for iterative improvement of this knowledge into the future by way of monitoring and new research.

The BA methodology supports the following objectives, from the Council of Australian Governments (COAG) and others:

  • understand the hydrogeologic and flow regimes of a bioregion prior to future CSG and coal mining development
  • understand the state and natural variation of key water-dependent assets located in the bioregion undergoing CSG and coal mining development
  • understand the characteristics of the target CSG and coal resources and hence the likely techniques, and associated water volumes, involved in their exploitation
  • for receptors identified for key water-dependent assets, understand the:
    • impacts of CSG and coal mining development during the extraction phase
    • post-mining impacts of CSG and coal mining development
    • direct, indirect and cumulative impacts of CSG and coal mining development
    • effects of natural variability on exacerbating or suppressing impacts of CSG and coal extraction.

1.3 Focus on significant water resources

The National Partnership Agreement on Coal Seam Gas and Large Coal Mining Development prescribes that the BAs focus on the impacts on water resources. CSG and large coal mining developments may have multiple impacts on the environment (National Research Council, 2010). For potential impacts to be assessed using the BA methodology, they must be considered (or mediated) through changes in water resource dependencies of receptors contained within water-dependent assets (see Sections 3.4 and 3.5 for more detail on water-dependent assets and receptors). For example, it is outside the scope of the BAs to assess changes in air quality that do not ultimately also influence the quality of water required by assets or receptors.

A water-dependent asset is an entity contained within a bioregion where the specific characteristics can be ascribed a defined value and which can be clearly linked, either directly or indirectly, to a dependency on groundwater or surface water quantity or quality. Receptors are discrete, identifiable attributes or entities associated with water-dependent assets that are materially impacted by change in water quality or quantity arising from CSG or coal mining development. Receptors are the primary mechanism for reporting on the direct, indirect and cumulative impacts in a BA. Response variables associated with receptors link receptors with impact models and recommended monitoring programs. These links are explained in detail in this document.

According to the National Partnership Agreement, a significant impact on water resources is caused by a single action – or the cumulative impact of multiple actions – that would directly or indirectly:

  • result in substantial change in the quantity, quality or flow regimes of surface water or groundwater
  • substantially alter groundwater pressure and/or watertable levels
  • alter the ecological character of a wetland that is state or nationally significant or Ramsar-listed
  • divert or impound rivers or creeks or substantially alter drainage patterns
  • reduce biological diversity or change species composition or ecosystem processes
  • alter coastal processes and inland processes, including sediment movement or accretion, or water circulation patterns
  • result in persistent organic chemicals, heavy metals or other potentially harmful chemicals accumulating in the environment such that biodiversity, ecological integrity, human health or other community and economic use may be adversely affected, or
  • substantially increase demand for – or reduce the availability of water for – human consumption or ecosystem services.

This scope of potential impacts guides local natural resource management and catchment management authorities in identifying the assets and receptors to be studied in BAs. Much of the impact and risk to receptors is dealt with, or mediated, through changes in water quantity or quality (with focus on salinity). For anthropogenic receptors, the impacts may be direct and quantifiable (see Section 3.5 for examples of receptors). For anthropogenic and/or ecological receptors, the variability – including the magnitude, frequency, reversibility and duration of these changes – is important to characterise.

The BA methodology is a 'best-practice' approach using best available data, information and models, and/or timely investment to fill gaps in data, information or models. It is anticipated that practical considerations will influence the degree to which any specific assessment achieves implementation of the full BA methodology. Where this occurs, the BA methodology specifies that science-based judgment is used, decisions are documented, and that products and workflow of BAs (as implemented in practice) are documented and made publicly available. Such documentation is critical to transparency and to the independent replication and confirmation of outcomes from BAs.

Because scientific knowledge used to inform policy and regulatory decision making is often incomplete, but continually improving, the BA methodology emphasises that uncertainty in the results from BAs be characterised and reported. There is a relationship between uncertainty in assessment outcomes and the degree to which the full BA methodology is implemented. It is expected that uncertainty is influenced by the availability of existing data, information and models, and to the degree that gaps in such are filled through investment in new data, new information, model enhancement or model development.

1.4 Organisation of this report

Chapter 2 provides a summary of components of the BA methodology. Chapters 3, 4 and 5 provide more details for components in the BA methodology summarised in Chapter 2. In order to achieve compatibility of data outputs, it is anticipated that coordinated archival and access to data resulting from BAs will be undertaken by the Bureau of Meteorology and that the lead research agencies, CSIRO and Geoscience Australia, will be engaged to undertake significant components of BAs. Importantly, state government agencies, natural resources management agencies and universities will provide crucial data and expert knowledge into the development of BAs.

Last updated:
7 March 2017