Indicators of Catchment Condition in the Intensive Land Use Zone of Australia – Soil degradation hazard

\n\nIt should be noted that this data is now somwhat dated!\n\nSoil degradation refers to any deterioration in the natural physical, chemical\nor biological properties of a soil, and is a function of soil texture, soil\nfabric, soil fauna and mineral and organic matter content. Soil degradation\nreflects the unsuitability of a land-use / management practice on a particular\nsoil type, and manifests itself as soil erosion (eg. loss of the topsoil),\ncompaction a causing loss of water holding capacity and permeability changes,\nacidification, salinisation, etc.\n\nThis issue is particularly relevant to property scale planning and management,\nbut off-site impacts can also be significant. Soil degradation is sensitive to\ncatchment scale changes, particularly where the change is direct.\n\nThe soil properties that affect land management, as identified within the\nAtlas of Australian Soils, have been rated according to their potential to\ndegrade under the land-uses practiced upon them. The land-use data has been\nrated by intensity into 10 classes. Both ratings are based on expert opinion.\n\nThe two rating systems have been combined spatially to produce a land-use\npractice-soil vulnerability surface, which has been re-classified into 5\nclasses ranging from low soil degradation hazard (nature conservation areas\nand/or soils having negligible physical and chemical limitations) through to\nhigh hazard (i.e. high intensity land-uses on highly vulnerable soils). The\nquality and reliability of data is limited by the coarseness of the soils\nmapping and the difficulties of defining soil classes over vast areas of\ninherently heterogeneous soil mosaics.\n\nSoil degradation hazard is an issue in many parts of the mid Murray-Darling\nBasin (Murrumbidgee, Murray-Riverina, Avoca and Loddon River basins) because\nof limy, powdery soils. This can cause poor crop response, and leave bare\nerodible ground. The biophysical impacts include loss of topsoil nutrients and\norganic matter. This results in vegetation re-establishment difficulties and\nthe loss of biodiversity.\n\nIn Queensland, the main soil management concerns are on the central to\nnorthern coast and correspond with sulphidic, waterlogged and sodic soils\n(Burdekin, Don, Haughton, Fitzroy, Calliope, Boyne and Ross Rivers).\nEngineering works associated with land development and other kinds of\ndisturbance, including drainage, cultivation and irrigation, have caused the\nsulphidic soils to be oxidised, causing sulphuric acid release to waterways.\nIn these areas, sodic soils readily disperse and erode, causing turbid\nstreams. In South Australia the catchment with the poorest rating is the\nMyponga River catchment. In Victoria the Barwon, Moorabool and Werribee River\nbasins have poor ratings. In Western Australia the catchments with poor\nratings are the Esperance Coast, Frankland, Blackwood, Avon, Moore-Hill, Yarra\nYarra Lakes and Murchison River basins.\n\nData are available as:\n\n * continental maps at 5km (0.05 deg) cell resolution for the ILZ;\n * spatial averages over CRES defined catchments (CRES, 2000) in the ILZ;\n * spatial averages over the AWRC river basins in the ILZ.\n\nSee [further metadata](http://data.daff.gov.au/anrdl/metadata_files/pa_iccilr9ab\n__05821axx.xml) for more detail.\n\n