Storage parameters

Upper and lower limits of the storage parameters for various hydrogeological formations modelled in this bioregional assessment (BA) were sourced from a review report by the University of Southern Queensland (USQ, 2011). The USQ (2011) study summarised such parameters and features of existing groundwater models for assessing cumulative drawdown impacts of CSG development in the Surat Basin. The initial specific yield (Sy) and specific storage (Ss) for the various hydrogeological formations and associated layers modelled in this BA were varied linearly with depth implementing the bounds listed in Table 7 (Bioregional Assessment Programme, Dataset 3). For example, in layer 2 the initial Ss in each model cell was changed linearly with depth from 1 x 10–6 to 1 x 10–4 m–1. These parameters were adjusted during model sensitivity and uncertainty analysis by implementing the multipliers listed in Table 6. The storage parameters, in particular the ones with the targeted coal seams, control the propagation of pressure. The ranges of the multipliers in Table 6 were selected conservatively to the best knowledge of the authors to avoid underestimation.

Table 7 Specific yield (Sy) and specific storage (Ss) ranges


Hydrostratigraphic unit

Generalised hydraulic characteristics

Sy and Ss range


Alluvium / volcanics / unconfined part of other units


Sy: 0.1 to 0.3

Ss: 1 x 10–5 to 1 x 10–3 m–1


Grafton Formation


1 x 10–6 to 1 x 10-4 m–1


Bungawalbin Member


1 x 10–7 to 1 x 10-5 m–1


Kangaroo Creek Sandstone Member


1 x 10–6 to 1 x 10-4 m–1


Walloon Coal Measures (Maclean Sandstone)


1 x 10–8 to 1 x 10–5 m–1


Walloon Coal Measures (coal seams)

Aquifer/aquitard (variable)

1 x 10–7 to 1 x 10-4 m–1

Sy is not required for confined hydrogeological units.

Data: Bioregional Assessment Programme (Dataset 3)

Last updated:
23 October 2018
Thumbnail images of the Clarence-Moreton bioregion

Product Finalisation date