Indicators of Catchment Condition in the Intensive Land Use Zone of Australia – Rivers through forests

\n\nIt should be noted that this data is now somwhat dated!\n\nRivers through forests a Length of river within forests per total length of\nriver in the catchment. Riparian vegetation acts as a buffer between the land\ncomponent of the catchment and the stream or river.\n\nForests are a sub-set of riparian vegetation that is quantifiable from\nimagery. Rivers passing through forested areas is a surrogate for the\ncondition of the riparian zone. The length of watercourses draining through\nforested areas gives a general indication of water quality and quantity\nmaintenance and improvement, through filtering, shading and cooling, and by\nimproved aquatic biota condition. Included in this definition of forest are\nshrub, scrub and woodlands.\n\nThe most detailed river dataset available is the Topo250K dataset from AUSLIG\n(2000). This scale is appropriate to catchment scale analyses and has been\nused for this indicator.\n\nTree cover was defined from the Australian Land Cover Change (ALCC) dataset\n(2000), which is also at 1:250K. cell is defined as aforesta if it has\ngreater than 20% tree foliage cover and greater than 2 m tall. Topo250K rivers\nare industry-accepted data with a satisfactory data collection methodology.\n\nThe positional and attribute accuracy of the original data are sufficiently\nreliable for this analysis. The ALCC (2000) data has several gaps in the ILZ,\nnotably in southern Victoria and near the boundary with the ELZ in many areas.\nThese gaps have been filled using Atlas of Australian Vegetation (Carnahan,\n1990) data at 1:5M scale. Reliability is good, except where Carnahan data has\nbeen stitched in.\n\nBased on this indicator, relatively good riparian/catchment condition\ncorresponds with most coastal catchments, the higher rainfall areas of North\nQueensland and the forested inland areas of West Australia. Relatively poor\nconditions are indicated for coastal and near-coastal catchments in\nsouthwestern Victoria and southeastern South Australia, and most particularly,\nthe Wakefield, Brighton, Mambray Coast, Willochra Creek, Spencer Gulf and Eyre\nPeninsula (SA) Broken, Campaspe, Loddon, Avoca, Wimmera-Avon, Hopkins and Lake\nCorangamite in Victoria. In Western Australia, the Avon River features most\npoorly. For NSW, the Lachlan, Lake George, Murrumbidgee and Murray-Riverina a\nsouthern parts of the Murray-Darling Basin are indicated as having relatively\npoor condition. In Queensland the condition based on this indicator is\ngenerally good. Other catchments with an indicated relatively poor condition\noccur in drier inland areas where vegetation is generally much less dense\n(that is it is not naturally forested).\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__06921axx.xml) for more detail.\n\n