Description: Hydrogeological Landscape (HGL) mapping has been conducted since 2007 across NSW, at various scales. The work has informed rural and urban salinity management plans, catchment action plans, natural resource management (NRM) plans, Land-care Network plans and landholder property plans. This innovative program allows us to understand the landscape, how it works and how to manage the landscape and to ‘put the right actions in the right place.Salinity occurs when water interacts with salts held in the landscape. HGLs delineate a uniform area of land that can be described by the specific rock, soil and water interactions occurring in that area. The HGL concept provides a structure for understanding how water moves through a landscape and how differences in water movement affect where salinity is expressed. An HGL spatially defines areas of similar salt stores and pathways to salt mobilisation and delineates management areas according to landform. This enables site-specific / landform-specific recommendations to be made on how best to manage salinity and prioritise landscapes. HGLs are described in written word, as conceptual cross-section diagrams and defined spatially as a map layer.The process of HGL determination relies on the integration of a number of factors: geology, soils, slope, regolith depth, climate, an understanding of different salinity development processes (‘plumbing’) and the impacts (land salinity / salt load / EC) in landscapes. Information sources such as soils mapping, site characterisation, salinity site mapping, hydrogeological data and surface and groundwater data are incorporated into standard HGL descriptions. For each defined HGL, management actions are assigned to specific management areas in each landscape. This improves understanding of the landscapes and assists with decisions to put the ‘right activities in the right locations’ in sub-catchments.The state wide HGL map captures HGL work conducted since 2007 by a range of technical groups across many departments as they have evolved through time. This map is a result of this former activity and is a compilation of all previous project work done at smaller scales from small subcatchment scale to Local Government area and river catchment scale.The shapefile was crated by merging multiple data sets of vector and raster data. The raster data was converted to vector format and topological corrections were made. Approximately 10 000 topology errors that resulted in the data set merges were removed by manual and automated techniques. The map was then reviewed for errors resulting from different catchment and other boundaries being used between the various merged products.Several workshops were held to assess data collected at farm and catchment scales for validity at a state wide scale. Adjustments to hazard ratings were made by assessing each one of the 544 HGLs with consideration of state wide relevance and importance to salinity management at the state level. Further editing of the map was done where improvements in geological or salinity knowledge and mapping since original work was available.
Copyright Text: Wayne Cook, Allan Nicholson, Andrew Wooldridge, Brian Jenkins, Rob Muller.