2.7.1 Methods


This section details the specific application to the Gloucester subregion of methods described in companion submethodology M08 (as listed in Table 1) for receptor impact modelling (Hosack et al., 2018).

In bioregional assessments (BAs), receptor impact models are intended to characterise potential ecosystem changes that may result from a given hydrological change predicted in response to coal resource development. A receptor impact model is constructed for a specific landscape class, which is defined as an ecosystem with characteristics that are expected to respond similarly to changes in groundwater and/or surface water due to coal resource development. Only those landscape classes that intersect the zone of potential hydrological change are considered to be candidates for receptor impact models. Outside the zone, hydrological changes are considered too small to result in adverse impacts to water-dependent ecosystems.

The potential impacts of coal resource development on ecological assets are initially assessed using qualitative mathematical models. These models are used to elicit from independent experts and contain key components and processes of the landscape class ecosystems, and the hydrological variables that support them. They then are used to qualitatively predict (reported as an increase, decrease or no change) how the landscape class ecosystem will respond to changes in hydrology that may occur as a result of coal resource development.

The receptor impact modelling process continues with selection of receptor impact variables from the ecological components or processes identified in the qualitative mathematical model and hydrological response variables to represent the hydrological regimes that support these components or processes. Thus the landscape classification and qualitative mathematical models form the bases for elicitations to quantify changes in receptor impact variables in response to simultaneous changes in hydrological response variables for subsequent model prediction.

The elicitation allows the BA team to construct a statistical model that predicts how changes in the hydrological response variables due to coal resource development will impact the receptor impact variables. Within a landscape class, this statistical model enables the BA team to quantify the risk to ecological assets of coal resource development using predicted changes in hydrological response variables in a short-term (2013 to 2042) and long-term (2073 to 2102) period.

The receptor impact models predict the distribution function of the receptor impact variables for different futures (baseline and coal resource development pathway) and at specific assessment years (2042 and 2102). The distribution functions are summarised in BAs by a limited series of percentiles (or quantiles), nominally 5% increments between the 5th and 95th percentiles.

Last updated:
13 November 2018