2.7.5.1 Description

The hydrogeological systems in the Hunter subregion are associated with aeolian sand aquifers in the coastal zone of the subregion (companion product 1.1 for the Hunter subregion (McVicar et al., 2015)) as illustrated in Figure 22. As discussed in Section 2.7.4.1.3, coastal sands typically support a single, unconsolidated sedimentary aquifer, in which groundwater forms a freshwater lens in the intergranular voids of the coastal sand mass. Estuarine and near-shore marine ecosystems located adjacent to coastal sand masses may also depend on the discharge of groundwater from these unconsolidated sedimentary aquifers.

The landscape classes within the ‘Coastal lakes and estuaries’ landscape group are based on mapping of coastal lakes and estuaries (NSW Department of Environment Climate Change and Water, Dataset 1), and mapping of saline wetlands (mangroves and saltmarshes) and seagrasses (NSW Department of Primary Industries, Dataset 2). For estuaries and lakes, the assessment team adopted the classification scheme used by the NSW Department of Environment and Heritage (Roper et al., 2011), which classifies estuaries and lakes into ‘Drowned valleys’, ‘Lakes’, ‘Barrier river’, ‘Lagoons’, and ‘Creeks’ based on dilution factors, tidal flushing times and geomorphology. Coastal lake and estuary landscape classes within the zone of potential hydrological change that are most likely to be associated with coastal aquifers are ‘Lakes’, ‘Lagoons’, ‘Saline wetlands’ and ‘Seagrass’. Groundwater-dependent ecosystem (GDE) landscape classes that could be associated with coastal aquifers (e.g. ‘Forested wetland’) are covered in Section 2.7.4. ‘Lakes’, ‘Lagoons’ and ‘Saline wetlands’ landscape classes are represented by the qualitative model for intertidal wetlands (Section 2.7.5.2); the ‘Seagrass’ landscape class is represented in the qualitative model for subtidal benthos (Section 2.7.5.3), but can be linked to the intertidal wetlands model via the seagrass node in the intertidal wetlands model. Thus, the two qualitative models describe a continuum across the land–water interface, reflecting the changes in communities with variations in degree of submergence from partial and intermittent to complete and permanent.