Observation data

The primary purpose of the Office of Groundwater Impact Assessment (OGIA) model is to predict the regional water pressure and water level changes in aquifers within the Surat cumulative management area (CMA) in response to depressurisation of the coal seams for coal seam gas (CSG) production. GHD (2012, p. 74) states:

‘Calibration of the regional steady-state model, which is intended to replicated [sic] long-term average conditions pre 1995 (i.e. pre CSG extraction), was undertaken through reference to average groundwater levels from 1,541 boreholes.’

Pre-1995 groundwater levels represent a period before significant CSG extraction and open-cut coal mine development in the Surat CMA. The Wilkie Creek Coal Mine commenced production in 1994, but is unlikely to have significantly affected the regional groundwater levels used in model calibration. For this reason, the OGIA model was not recalibrated when the open-cut coal mine boundary conditions were added for the bioregional assessment (BA) groundwater modelling in the Maranoa-Balonne-Condamine subregion.

‘Storage values were calibrated, as far as possible, using the transient sub-model developed for the Kogan North and Daandine well-field. As observed groundwater levels were only available for the productive coal of the WCM (model layer 10) in the Kogan North/Daandine area, only the storage value for this layer can be considered to have been calibrated using this model’ (GHD, 2012, p. 93).

Last updated:
17 October 2018
Thumbnail of the Maranoa-Baloone-Condamine subregion

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