2.1.3 Hydrogeology and groundwater quality


The Gloucester subregion contains 175 groundwater bores where four types of hydrogeological data were analysed: (i) groundwater level, (ii) hydraulic parameters, (iii) groundwater quality and (iv) allocation.

Mean groundwater levels and bore depths were determined for various aquifers of the Gloucester subregion including the alluvial aquifers, the fractured rock aquifers and the deep water-bearing units. This information is crucial to the identification of recharge and/or discharge areas and associated groundwater flow systems, as well as for the development of the groundwater balance for the subregion as well as aid in preliminary identification of areas that can potentially be impacted by coal seam gas extraction and coal mining activities.

Overall the availability of hydrogeological and hydrochemical data is limited for alluvial and fractured rock aquifers. For the deeper water-bearing systems, there is next to no information available.

Based on the geological setting and discrete structural-sedimentary formation (see McVicar et al., 2014, Figures 22 and 23), the geological Gloucester Basin, which underlies the Gloucester subregion, is characterised as a closed hydrogeological system. The Gloucester subregion containes two main aquifers: an alluvial aquifer and an aquifer hosted by a weathered bedrock profile occurring within 150 metres below ground level. Further detail about the hydrogeological settings of the Gloucester subregion is provided in Section 1.1.4 of the companion product 1.1 for the Gloucester subregion (McVicar et al., 2014). Multiple groundwater studies describe four main hydrogeological units within the Gloucester subregion:

  1. alluvial aquifers along major creek lines (referred hereafter as alluvium)
  2. relatively shallow weathered and/or fractured rock aquifers (referred hereafter as fractured rock)
  3. interburden units of very low permeability which form a thick succession of low permeability coal measures (referred hereafter as deep water-bearing)
  4. the impermeable Alum Mountain Volcanics Formation that underlies these three hydrogeological units.

Hydrogeological data, including aquifers, water levels and hydraulic properties, are required to inform groundwater modelling. In addition, estimates of the extraction of groundwater for use are needed. Information about the quality of water within aquifers enables assessment of potential impacts from aquifer mixing and discharge of aquifer water into other receiving waters. The hydrogeologic data used in the bioregional assessment (BA) of the Gloucester subregion are detailed in Section about observed data.

Last updated:
26 October 2018
Thumbnail of the Gloucester subregion

Product Finalisation date