2.6.2.3 Model development

Summary

A regional-scale numerical groundwater model was built using the MODFLOW-USG code to evaluate the changes in groundwater due to additional coal resource development in the Namoi subregion.

The groundwater model consists of up to nine hydrostratigraphic layers with the alluvium, Pilliga Sandstone, Hoskissons Coal and Maules Creek Formation explicitly included and other formations lumped into interburden layers. The modelling domain spans an area of about 59,000 km² with thickness exceeding 1500 m. It is represented by a variable Voronoi mesh with a resolution of 300 m around coal resource developments and streams, increasing to 3000 m in areas remote from the coal resource developments and streams.