1 Introduction

1.1 Background

The Methodology for bioregional assessments of the impacts of coal seam gas and coal mining development on water resources (the BA methodology; Barrett et al., 2013) describes a multidisciplinary scientific approach to assess the potential impacts of coal resource development on water resources and water-dependent assets. Figure 3 is a simple diagram of the four components in the BA methodology.

Figure 3 The components in a bioregional assessment

In Component 1: Contextual information, the context for the BA is established and the relevant information is assembled. This includes defining the extent of the subregion or bioregion, then compiling information about its ecology, hydrology, hydrogeology and geology, as well as water-dependent assets, coal resources and coal resource development. In Component 2: Model-data analysis, the information is analysed and transformed, by developing and using the conceptual model of causal pathways, geological models and hydrological models, in preparation for Component 3: Impact analysis and Component 4: Risk analysis.

The BA methodology is designed to include as much relevant information as possible and to retain variables in the assessment until they are ruled out of contention. Further, estimates of the certainty, or confidence, of the decisions are to be provided where possible, to assist the user to evaluate the strength of the evidence.

1.2 Role of this submethodology in a bioregional assessment

The BA process is complex, as shown in Figure 4 which includes all the supporting submethodologies, workshops and technical products. Readers should consider this submethodology in the context of the complete suite of methodologies from the Bioregional Assessment Programme (see Table 1), particularly the BA methodology (Barrett et al., 2013), which remains the foundation reference that describes, at a high level, how BAs should be undertaken.

An impact and risk analysis is the key output of the BAs. The BA methodology (Barrett et al., 2013) states:

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.

While the BA methodology gives a high-level overview of the components and conceptual workflow, it is not detailed enough to clearly guide assessment teams performing a BA. This is consistent with the intent of the BA methodology, which is analogous to an architect’s design sketches. These sketches lay out the look and feel of the building and provide a guiding vision of the completed project. But to build it the architect needs to develop working drawings that explicitly show the detail of the construction that the tradespeople can use to actually construct the building. This submethodology performs the same role for BAs. Using the concepts in the BA methodology, it provides the overall scientific logic that runs through all components and the companion submethodologies, and culminates in the impact and risk analysis for a bioregion or subregion. Some details of the analysis are included here – mainly sufficient details so that users can efficiently generate high-quality impact and risk analyses for BA purposes – but otherwise this submethodology cross-references other submethodologies for details (e.g. to undertake hydrological modelling or receptor impact modelling).

The impact and risk submethodology for BA was developed and refined over time. It reflects learnings from the logistical and scientific challenges that arose in the application and evolution of the methodology. This submethodology describes the final process used to generate the assessments for the different regions, and also provides the reasoning behind the particular design choices that were made.

This submethodology includes the following: