2.3.3 Ecosystems

Summary

To deal with the complexity of a large number of diverse assets, a landscape classification was developed to group assets with similar hydrological function. Landscape classes were identified within five broad groups: ‘Riverine’, ‘Groundwater-dependent ecosystems (GDEs)’, ‘Estuarine’, ‘Non-GDE vegetation’ and ‘Economic land use’. Less than 3000 ha of the preliminary assessment extent (PAE; 46,820 ha in total) fell into the ‘Riverine’, ‘Estuarine’ and ‘Groundwater-dependent ecosystem (GDE)’ landscape groups. Seven landscape classes in the ‘Riverine’ landscape group were defined based on hydrology and river bed substrate. The dominant ecohydrology was perennial streams and lowly intermittent streams, and the dominant river substrate was gravel/cobble. Both types of streams are expected to have significant groundwater dependence in addition to surface water dependence. Five landscape classes in the terrestrial ‘Groundwater-dependent ecosystem (GDE)’ landscape group were defined based on vegetation formations: ‘Rainforest’, ‘Forested wetlands’, ‘Freshwater wetlands’, ‘Wet sclerophyll forests’ and ‘Dry sclerophyll forests’. Both the mapping of vegetation and the nature of the water dependence of some identified GDEs are significant sources of uncertainty. Possible water-dependencies of each landscape class in the ‘Groundwater-dependent ecosystem (GDE)’ landscape group are suggested based on vegetation descriptions and expert advice. Two landscape classes in the ‘Estuarine’ landscape group are defined: the Karuah River estuary is classified as a ‘Barrier river’ while the fringing vegetation of the estuary is defined as ‘Saline wetlands’. Both are likely to have tidal influences in addition to possible groundwater and surface water dependencies. Of the remainder of the PAE, there are 13,000 ha of non-GDE native vegetation and 31,000 ha of cleared land that is mainly dryland agriculture (28,000 ha) and intensive uses (2,000 ha).