The qualitative uncertainty analysis in Section lists the major assumptions and model choices that form the basis of the probabilistic assessment of the impacts of coal resource development on groundwater-related receptors in the Gloucester subregion. Within the context of the goal of the Bioregional Assessment Programme, the bioregional assessment for the Gloucester subregion (the Assessment) modelling team deemed these assumptions valid and acceptable. There is no guarantee, however, that these assumptions will hold or be acceptable to address any other water management questions in the region; therefore, the Assessment modelling team recommends not using these models for any other purpose without a formal assessment of the suitability of the conceptualisation, parameterisation and implementation for the changed objective.

Should these models be considered for any other purpose, there should be a formal re-evaluation of the suitability of the conceptual model and model assumptions, in line with the Australian Groundwater Modelling Guidelines (Barnett et al., 2012). All model files and executables are available through the Bioregional Assessment Information Platform (Bioregional Assessment Programme, 2016). It is recommended to contact the model development team for detailed information on the groundwater models.

The chain of models described in this report is designed to estimate the direct and indirect impacts on a regional scale. This means trade-offs are made in terms of local resolution of the model. Especially in the immediate vicinity of coal mines, the effect of coal mining activity will be largely dominated by local variations in geology and hydrogeology. The reliability of any predictions made by this regional model will be inferior to the reliability of predictions made by a local groundwater model that fully accounts for this level of detail.

The models are designed within a probabilistic framework. This implies there is not a single parameter combination that provides a ‘best fit’ to observations and a corresponding single set of predictions. Any evaluation or further use of both the parameter combinations used in the models or the predictions need to take into account the full posterior distributions reported in Section . These are also available through the Bioregional Assessment Information Platform (Bioregional Assessment Programme, 2016).

The utmost care has been devoted to ensuring the results presented are in accordance with the conceptual understanding of the system and the stresses imposed on it. This is mostly done by targeted spot checks of model outputs as presented in Figure 20 and visual examination of the response of model outputs to varying parameter values, such as presented in Figure 24 and Figure 25. While these checks minimise the risk that artefacts have gone undetected, as in any modelling exercise of this scale, there is no guarantee that there are no artefacts of modelling included in the results.

Last updated:
5 November 2018
Thumbnail of the Gloucester subregion

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