2.7.1.1 Background and context

In BAs, receptor impact modelling attempts to capture the direct, indirect and cumulative impacts of coal seam gas (CSG) and coal mining development on the ecosystems that exist within landscape classes or landscape groups. The aim of receptor impact modelling is to convert the potentially abstract information about hydrological changes into quantities (risk assessment endpoints) that stakeholders care about and can more readily understand and interpret. In particular, the model outcomes are anticipated to relate more closely to stakeholder values and beliefs and therefore support community discussion and decision making about acceptable levels of development.

The causal pathways that describe how coal resource development may lead to changes in hydrology are identified in companion product 2.3 for the Galilee subregion (Evans et al., 2018). The receptor impact models generate predictions that represent the subsequent pathways which relate changes in hydrological response variables to potential impacts on water-dependent landscape classes and assets that occur within the zone of potential hydrological change.

To better understand the potential impacts of coal resource development on water resources and water-dependent assets such as wetlands and streams, receptor impact modelling for BAs deals with two potential futures:

The difference in results between CRDP and baseline is the change that is primarily reported in a BA. This change is due to the additional coal resource development – all coal mines and CSG fields, including expansions of baseline operations, that are expected to begin commercial production after December 2012. In receptor impact modelling, however, the critical change is the difference between average groundwater and surface water conditions in the reference period (1983 to 2012), compared to predicted average conditions under the baseline and the CRDP in the short term (2013 to 2042) and longer term (2073 to 2102). As noted in companion product 2.3 for the Galilee subregion (Evans et al., 2018), the baseline future in the Galilee subregion does not have any coal resource development, as there were no commercially producing coal mines or CSG fields as at December 2012 (the baseline date).

This product presents the receptor impact modelling for the Galilee subregion. The modelling approach is described in detail in the companion submethodology M08 (as listed in Table 1) for receptor impact modelling (Hosack et al., 2018). Section 2.7.1.2 of this document describes how this methodology is applied to the Galilee subregion.

The following terms are used throughout the receptor impact model products to describe the modelling process and its results: