Indicators of Catchment Condition in the Intensive Land Use Zone of Australia – Rivers in salt hazard

\n\nIt should be noted that this data is now somwhat dated! The proximity of parts\nof a river network to saline soils is an indicator of the propensity for\nsaline river flows. This information can be used to guide catchment scale\nplanning and management towards land management practices to maintain water\ntables at depths well below the surface in near-stream areas. Sensitivity is a\nfunction of how rapidly land-use changes cause hydrological changes affecting\nstream flow and groundwater conditions.\n\nThe most detailed river data available is the AUSLIG 1:250K TOPO data. This\nscale is appropriate to catchment scale analyses and has been used for this\nindicator. The saline soils coverage is derived from the Atlas of Australian\nSoils (Northcote, 1968), which was mapped at 1:2M scale.\n\nThis indicator is calculated as length of stream draining saline soils divided\nby total length of stream. The quality and reliability of the data set is\nlimited by the coarseness of the soil mapping.\n\nBroadly, it is reasonable to expect that if the sources of salt within a\ncatchment are close to streams, stream water will be more saline than for\nareas where salt sources are remote from streams. However, interpretation is\nnot unequivocal as the hydrologic connectivity of alluvial soils is not\nspatially uniform and the quantity of salt within asalt hazard soilsa and its\navailability are not defined. The indicator has not been validated against\nstream salinity data, but the relationship is easy to understand by users.\nSome level of validation could be achieved using the stream reach and\nexceedence data when available. The greatest density of high salt risk is in\nthe north and west-flowing tributary catchments of the Murray and Darling\nRivers, most notably the Broken River, Loddon, Avoca, Murray-Riverina,\nLachlan, Mallee, Wimmera-Avon Rivers, Moonie, Gwydir, Namoi, Castlereagh, and\nthe Macquarie-Bogan Rivers. The Gawler, Wakefield and Broughton Rivers in\nSouth Australia are shown as in the poor category (high risk). The Burdekin,\nDon, Calliope and Boyne River basins in Queensland have an indicated\nmoderately poor condition. The upper reaches of the Greenough, Blackwood and\nAvon River Catchments (WA) have a relatively poor condition.\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__05521axx.xml) for more detail.\n\n