While there are many groundwater bores and a large number of groundwater observation bores in the Gloucester subregion, there are some distinct data and knowledge gaps. The most significant gaps that could potentially influence achieving realistic simulation and modelling based analysis are:

  • While areas around the mines have a very good coverage with shallow groundwater observation bores, there is a general lack of groundwater observation bores in other parts of the Gloucester subregion. This lack of data in some areas impacts on the uncertainty of recharge estimation for the alluvial aquifer.
  • There is a general lack of deep groundwater observation bores, as most observation bores (and more generally the majority of all groundwater bores) are less than 50 m deep. While there are approximately 175 bores in the Gloucester subregion, most are relatively shallow and located either in alluvium or in fractured rock aquifer. However, as the deep water-bearing units are more than 150 m deep throughout most of the basin, the existing groundwater monitoring network is likely to capture only a small component of the hydrodynamics of the Gloucester subregion. Critical hydraulic information including water level, hydraulic properties and water chemistry of bedrock aquifers is currently missing.
  • There is a general lack of nested (multi-level) bore sites throughout the Gloucester subregion. While groundwater dynamics in shallow alluvial aquifers are relatively well understood, there is very limited knowledge on characteristics such as groundwater flow direction or inter-aquifer head gradients throughout much of the bioregion.
  • There are significant gaps in the groundwater databases. For example, there is no ‘aquifer’ layer where the screened interval of bores is assigned to a specific aquifer in the National Groundwater Information System groundwater database (Bioregional Assessment Programme, Dataset 7; NSW Office of Water, Dataset 1). More information about hydraulic properties of key aquifer units needs to be obtained. In particular, information about the deep water-bearing units is required for the numerical model development to assess the impacts associated with coal seam gas development.
  • The hydraulic significance of faults is poorly understood due to the lack of nested (multi-level) groundwater monitoring sites. Only limited understanding exists about the role of faults as potential pathways or barriers for aquifer interconnectivity or groundwater flow to the surface. More work, such as the use of remote sensing to identify faults that penetrate to the surface, may be required in the future.
  • The quality of the hydrochemistry data available for this Assessment is difficult to determine, as analytical uncertainties are not reported in the dataset. The dataset includes chemical analyses of differing ages, sometimes decades apart, which will have differing levels of accuracy and precision. Additionally, bore screening interval data are unknown and stratigraphic unit information was not assigned in the database.
  • A number of potentially harmful trace elements have not been reported in this product due to scarcity or absence of data. Some elements have data available for only one or two hydrogeologic units, while others have no data available at all.
Last updated:
14 June 2018
Thumbnail of the Gloucester subregion

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