2.6.2.1 Methods

Summary

Coal resource development in the Maranoa-Balonne-Condamine subregion has the potential to directly affect groundwater conditions and indirectly affect deep soil drainage, surface water – groundwater interactions, streams and surface water catchments. Potential hydrological effects of coal resource development on the surface water system are changes to surface water quality, direction, flow and volume. Hydrological changes to the groundwater system can also affect groundwater quality, aquifer properties, groundwater composition, flow (reduction), level and pressure.

The Queensland Office of Groundwater Impact Assessment (OGIA) regional groundwater model is considered a fit-for-purpose regional-scale groundwater model for the Bioregional Assessment (BA) Programme. The OGIA model is re-run annually based on the latest available industry development plans and has been revised for the BA to also simulate water-related impacts of coal mine developments in the Maranoa-Balonne-Condamine subregion. Integration of the groundwater model with a surface water numerical model and receptor impact modelling is not possible at this time in the Maranoa-Balonne-Condamine subregion for two reasons. Firstly, there is limited availability of long-term, consistent water quality and water quantity data measurements. Secondly, the OGIA model is focused on the deep regional aquifers targeted by coal seam gas (CSG) development, which means that it may not on its own be suitable for assessing hydrological changes in surficial aquifers. For these reasons, the Assessment team have not developed a coupled surface water and groundwater model, but have leveraged existing state-based resources and knowledge for this Assessment.