2.5 Water balance assessment for the Clarence-Moreton bioregion

Executive summary

​Rainforest waterfall in Border Ranges National Park, NSW, 2008 Credit: Liese Coulter, CSIRO

This product uses results from surface water and groundwater numerical modelling to assess how water balances might be different as a result of coal resource development in the Clarence-Moreton bioregion for three time periods: 2013 to 2042, 2043 to 2072, and 2073 to 2102.

 Water balances are reported for the two futures considered in a bioregional assessment:

  • baseline coal resource development (baseline): a future that includes all coal mines and coal seam gas fields that were commercially producing as at December 2012
  • coal resource development pathway (CRDP): a future that includes all coal mines and coal seam gas fields that are in the baseline as well as those that were expected to begin commercial production after December 2012.

The difference in results between these potential futures is due to the additional coal resource development – all coal mines and coal seam gas fields, including expansions of baseline operations, that were expected to begin commercial production after December 2012.

In the Clarence-Moreton bioregion there is one operational mine, Jeebropilly Mine in Queensland, which is in the baseline for this bioregional assessment. The additional coal resource development mapped for this assessment is the West Casino Gas Project in northern NSW. This development is no longer proceeding; however, this decision was made after the coal resource development pathway was agreed for modelling potential impacts in this region.

Water balances for the Clarence-Moreton bioregion

The groundwater balance analysis was conducted for the entire groundwater model domain, which covers an area of 8230 square kilometres. The overall change in groundwater balance due to the West Casino Gas Project is very minor. For example, in 2013 to 2042 the predicted median mean annual extraction due to the West Casino Gas Project corresponds to 0.02% of the median mean annual recharge. A larger change in groundwater water balance close to the CSG development is possible and would need to be evaluated with a finer-scale model.

The surface water balances comprise rainfall, surface water outflow, and losses (including evapotranspiration and water extractions). The analysis covers an area of 2942 square kilometres and is reported at four locations: the Richmond River above Casino, the Richmond River above Kyogle, Shannon Brook above Yorklea, and Eden Creek. The median change in surface water balance at all four model nodes due to the West Casino Gas Project was essentially zero (less than 0.05 gigalitres total) for each of the three reporting periods.

This analysis is part of a series of products, which describe how water balance is potentially impacted by coal resource development into the future. This product informs impact and risk analysis (Component 3 and 4) products, which examine the risk to, and potential impacts on, water resources and water-dependent assets due to coal seam gas or coal mining developments.

Last updated:
11 July 2017