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In this section you will find detailed information, including national overviews and state and regional level assessments, from the 2000-2002 National Land and Water Resources Audit theme assessments.
Australian Catchment, River and Estuary Assessment 2002
National Land and Water Resources Audit, 2002
ISBN 0 642 37125 3
Catchments Summary
Land use linked by water
- The Australian catchment condition assessment presents a way to make comparative assessments of catchment biophysical condition. Australia-wide reports and maps presented allow detailed and location-specific condition comparisons to be made. Comparisons at river basin and subcatchment scales are available as part of the Australian Natural Resources Atlas.
- The assessment provides insight into the biophysical condition of Australia's more intensively used catchments. Most catchments in the lower condition classes have been identified as priorities under the National Action Plan for Salinity and Water Quality (Commonwealth of Australia 2000). Notable areas for remedial works outside the National Action Plan for Salinity and Water Quality include the Hunter and Hawkesbury River basins in central New South Wales and smaller coastal river basins in northern New South Wales, southern and central Queensland and coastal Victoria (Figure 13).
- Using the composite catchment condition index:
- 5% of catchments are in the lowest condition class (< 20 percentile);
- 15% are in the lower condition class (20-40 percentile);
- 50% are in the mid-range condition class (40-60 percentile); and
- 30% are in the highest condition classes (> 60 percentile).
- The biophysical condition of a significant proportion of catchments (15-25%) is likely to continue to decline because of the long-term nature of environmental processes and degree of change in the catchment. These catchments are in the cleared, agronomically marginal rainfall areas, and have soils of relatively poor fertility and structural properties. They are prone to soil structure decline, soil erosion and salinisation and have low flexibility in terms of profitable land use options.
- Catchments in the lower condition classes are in the areas of most intensive land use. Improving land use practices is the key to improved condition for these catchments.
- At the other end of the scale, the 30% of catchment in the highest condition classes provide an indication of priorities for protective management - strategic investment will be cost-effective and ensure the maintenance of good condition of these catchments.
- This assessment has demonstrated that spatial pattern and variation in catchment condition can be described by using relatively few attributes - change in vegetative cover, native vegetation fragmentation, inputs into rivers and streams, and changes to catchment hydrology, particularly impoundments. These attributes all relate to land use intensity.
Introduction
Photo: Jim Tait.
Catchment management is a key community process in place across much of Australia. The House of Representatives Standing Committee on Environment and Heritage Inquiry into Catchment Management (December 2000) noted that a catchment management approach combines three ingredients necessary to address environmental problems facing the nation. There are:
- use of natural geographic divisions that are readily understood;
- a basis for linking communities of similar and shared interests into regions of interest, to build a stronger and coordinated response to environmental degradation; and
- widespread community acceptance of the approach and existing infrastructure.
For these reasons the Standing Committee concluded that:
... an approach based on the management of catchment systems
must underpin the identification of the problems, the administrative
arrangements and ultimately the delivery of appropriate remedial action.
House of Representatives Standing Committee of Environment
and Heritage 2001
The Standing Committee noted that not only is this approach based upon natural facts about the landscape, but that it already enjoys considerable and widespread support.
Recognising both the widespread community support for catchment management approaches and the importance of linked biological and physical processes in determining the condition of catchments, the catchment assessment was designed to assess the relative biophysical condition of Australia's catchments. It is restricted to the key catchments of intensive land use across Australia (Figure 7) and includes data sets from many of the other Audit assessments.
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.
Project objectives
- To develop a classification system that uses biophysical data to define catchment condition and provides an integration and synthesis of Audit data at the catchment scale
- To apply the classification system to provide an integrated Australian-wide report on the relative condition and main pressures operating on catchment condition
- To develop and provide a readily applied and extendable database and presentation framework for compiling, analysing and integrating catchment condition data with consideration to the capacity to integrate data across a range of scales
- To provide catchment specific information that allows decision makers to identify implications for catchment management needs, including information gaps and priorities for more intensive investigation and further research
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