2.3.2 Summary of key system components, processes and interactions


This section summarises the connections in the hydrological cycle of the Maranoa-Balonne-Condamine subregion. The spatial extent of the water flows and pathways is limited to the subregion preliminary assessment extent (PAE). The PAE extends beyond the northern and eastern subregion boundaries to include areas of the Hutton, Clematis and Precipice sandstone aquifers and shallower aquifers that may be affected by coal seam gas (CSG)-related groundwater extraction within the subregion and 5 to 7 km from the Dawson, Moonie and Weir rivers outside of the subregion boundary to encompass potential downstream surface water impacts.

Coal mining and CSG development in the Maranoa-Balonne-Condamine subregion targets the Walloon Coal Measures of the Surat and Clarence-Moreton geological basins. Important groundwater systems in the subregion are alluvial aquifers associated with major rivers (and antecedent systems), basalt aquifers associated with the Main Range Volcanics and aquifers of the Surat Basin within the Great Artesian Basin (GAB). The Condamine Alluvium and Main Range Volcanic aquifers are important water sources for irrigation, stock and domestic and town water supplies. The Condamine Alluvium is the most important and highly developed alluvial groundwater system in the subregion.

Coal resource development in the Maranoa-Balonne-Condamine subregion has the potential to directly affect the regional groundwater and surface water systems. Hydrological changes to the groundwater system can propagate through the alluvium and other aquifers to indirectly affect surface water – groundwater interactions in the aquifer outcrop and subcrop areas. Connectivity by direct linkages due to faulting and fracturing enhances the effects of groundwater level changes due to extraction. However, the role of faults and fractures as conduits or barriers to flow, their location in three dimensions, and their propensity to change their nature due to water pressure changes are all poorly known in the Maranoa-Balonne-Condamine subregion.

River basins in the PAE of the Maranoa-Balonne-Condamine subregion are the Border, Condamine-Balonne (including the Maranoa River), Fitzroy and Moonie rivers. Most river systems are temporary, with the exception of parts of the Dawson River, which receives baseflow contributions from rejected GAB recharge in the aquifer outcrop areas. The ephemeral nature of the surface water systems means that the management, treatment and disposal of water can affect surface water – groundwater interactions.

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

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