Hydrogeological Landscapes of New South Wales and the Australian Capital Territory

Hydrogeological Landscape (HGL) boundaries and descriptions have been derived for a number of project areas across NSW.

The HGL concept provides a structure for the understanding of how salinity manifests itself in the landscape and how differences in salinity are expressed across the landscape. A HGL spatially defines areas of similar salt stores and pathways for salt mobilisation. The process of HGL determination relies on the integration of a number of factors: geology, soils, slope, regolith depth, and climate; an understanding of the differences in salinity development; and the impacts (land salinity/salt load/water electrical conductivity) in landscapes. Information sources such as soil maps, site characterisation, salinity site mapping, hydrogeological conditions and surface and groundwater data are combined to develop standard descriptions for each HGL unit.

Derivative maps showing overall salinity hazard and individual hazard due to salinity expressed as land salinity, salt export (load) and stream EC are available for most mapped areas, and are also viewable as custom layers in eSPADE.

Overall salinity hazard uses a five class system (very low, low, moderate, high, very high). This helps the user identify and prioritise where salinity management actions may need to be targeted.

Hazard due to salt land, salt export and stream EC uses a three class system (low, moderate, high). Knowing which of these are of greater significance in a HGL unit helps the user decide on the types of management actions that may be applied.

Spatial resolution varies between 1:50 000 and 1:250 000, depending on the resolution of the source data used to define the HGL boundaries.