2.3.2 Summary of key system components, processes and interactions


Surface water and groundwater flows in the Hunter subregion are dominated by the nature of surface regolith layering and faulting. Diffuse recharge from rainfall occurs across the subregion, with increased rates in sandy alluvial deposits, in areas of exposed rock where weathering has resulted in increased hydraulic conductivities, and in coastal dunes and sand deposits. Discharge can occur locally – to springs, alluvial aquifers and rivers – and become increasingly regional in scale where flows discharge to the ocean. Rivers and streams in the Hunter subregion are closely coupled with alluvial deposits and aquifers, with bi-directional flows expected. The balance between river leakage and baseflow discharge is dependent on climatic variation.

Coal mine operations can affect surface water flows directly by altering surface water flow paths, or changing groundwater gradients in the immediate vicinity of operations. Underground mines reduce the groundwater level in their local coal seams, and may induce land surface changes through subsidence and upsidence. The role of faults as either conductors of water or barriers to flow in their pre-mining state is not understood equally across the subregion. Changes to the way faults operate, or the creation of new fractures, that may occur as the result of their interaction with open-cut and underground mining activities is recognised as a knowledge gap.

Last updated:
18 January 2019