The distribution of streamflow gauging stations in the Hunter subregion enables a reasonable understanding of the total flux of water within the river network. With monitoring for the HRSTS there is also a good dataset for stream salinity at several places in the regulated Hunter River alluvium. Although there is also acceptance of the close coupling of the river and alluvial aquifer, there is generally less knowledge of the magnitude and timing of exchanges and their contribution to maintaining baseflow. This gap makes generating a consistent and robust regional water balance of recharge and discharge very difficult.

The Assessment team does not have a good understanding of the spatial and temporal variance in the river-shallow aquifer hydrological exchange. These variations are important in maintaining redox gradients and biogeochemical processes in the river sediments that play major roles in river metabolism, especially during low flows.

The locations of many faults and geological structures are mapped in the normal course of geological exploration and mining developments. Their mere presence, however, provides no indication of the extent to which they act as conduits of water between strata over different depths. Inferences can be made about the hydrological function of faults by measuring stream salinity and chemistry with a run of river. Such measurements have not been carried out consistently across the subregion, so the role of faults, if any, in enhancing hydrological connectivity remains to be investigated. Targeted monitoring would be required for such a set of measurements to ensure the greatest chance of detecting discharge from a fault in the river chemistry, by ensuring the right flow conditions and being unimpeded by anthropogenic causes such as dam management or operation of HRSTS releases.

Last updated:
18 January 2019