A composite index was used in the overall assessment of catchment condition in Australia, during the National Land and Water Resources Audit1. The index was based on 14 indicators which were used to form three sub-indexes:
- water condition (e.g. suspended sediment ratio, pesticide hazard, industrial point source hazard and impoundment density);
- land condition (e.g. predicted 2050 salinity, soil degradation hazard and hillslope erosion ratio); and
- condition of biota (e.g. native vegetation fragmentation, extent of native vegetation, protected areas, road density, feral animal density and weed density).
Coastal issues arising from catchment degradation
Coastal waterways with highly disturbed catchments may have to contend with the following problems:
- destruction of critical habitats for development purposes (with potential runoff from acid sulfate soils);
- contaminants derived from stormwater and urban and industrial point sources (and related issues such as fish kills and shellfish closures);
- contaminants from agricultural areas (and related issues such as fish kills and shellfish closures);
- changed freshwater flow regimes;
- increased loads of fine sediments;
- nutrients from diffuse and point sources, potentially leading to eutrophication and related problems such as algal blooms, anoxic & hypoxic events, fish kills and shellfish closures; and
- an overall reduction in biodiversity.
Existing information and data
More information and maps showing the overall catchment condition index, the sub-indices and indicators can be found at the Catchment Condition Online Maps website 2. Appendix I (pp. 311-312) in Volume 2 of the Australian Catchment, River and Estuary Assessment, 2002 contains a map of Australia’s River Basins and Drainage Divisions in which each river basin has been assigned a number. These catchment numbers can be matched to a large number of coastal waterways in pages 316-363 of the same document. The catchment condition index for a large number of river basins are available in Appendix B (pp 65-76) of the Assessment of Catchment Condition in Australia’s Intensive Land Use Zone: A biophysical assessment at the national scale 1.
- The assessment of catchment condition was conducted as a partnership between the Audit, the Bureau of Rural Sciences and CSIRO Land and Water with support and involvement of State and Territory natural resource management agencies. The final report (Project 7/8) to the National Land and Water Resources Audit by Walker, J., Veitch, S. Braaten, R., Dowling, T., Guppy, L., Herron, N (2001) is entitled Assessment of Catchment Condition in Australia’s Intensive Land Use Zone: A biophysical assessment at the national scale
- Catchment Condition Online Maps website at the Department of Agriculture, Fisheries & Forestry.