Assessment of river and wetland health
AWR 2005 assessment of river and wetland health presents the following:
- a National Framework for the Assessment of River and Wetland Health (FARWH) (the framework includes supporting technical documents)
- testing and implementation of FARWH in Victoria and Tasmania using the existing river health assessment programmes (wetland assessment programmes are under development)
- a snapshot picture of river and wetland health of Australia that is based on previous broad scale assessments.
Collecting fish data using back pack electro fishing equipment in the Coliban River, Victoria.
Image by Sam Hannon, sourced from SKM
- AWR 2005 has developed an overall framework for the assessment of river and wetland health that can be applied to SWMA’s to deliver a national overview. The framework analyses data for six key river health criteria:
1. Physical form
2. Water quality and soils
3. Aquatic biota
4. Hydrological disturbance
5. Fringing zone
6. Catchment disturbance.
The results are then aggregated and ranked in classes between zero (severely degraded) and one (pristine), but individual criteria can be reported if required.
- The new framework was tested successfully on Victorian and Tasmanian data, but will require further trialling in other states and territories and further development with respect to wetlands.
- The new framework was tested successfully on Victorian and Tasmanian data. Additional trials are required in other states and territories, and further development is necessary for use of the framework in wetlands, as current trials are restricted to river health. It is not intended that the Framework replace the existing assessment systems in Tasmania and Victoria. Its aim is to provide a system of assessment for other jurisdictions based on and thus equivalent to those already in use in these two states.
- In the Victorian and Tasmanian trials, water management areas exhibiting a lower level of overall condition include the Moorabool, Loddon, Campaspe, Avoca, South Gippsland and Hopkins River surface water management areas in Victoria, and the Jordan Surface Water Management Area in Tasmania.
- From the National Commentary of river and wetland health, the following observations can be made:
- More than 80 per cent of the river length assessed across Australia was affected by catchment disturbance. Reaches in Tasmania and the Northern Territory were considered the least affected by catchment disturbance.
- From previous studies, hydrologic change could be assessed only in 25 per cent of the river length; this was due to a lack of data. In about 20 per cent of the assessed regulated river length, the flow regimes were largely unmodified from an ecological perspective.
- Stream habitat was modified from pre-European conditions in more than half of the assessed river length. Degradation of the habitat was considered to be largely because of changes in the sediment loads that alter channel morphology and loss of riparian vegetation. Scores for habitat were lowest in New South Wales, South Australia and Western Australia.
- Loads of nutrients and suspended sediment were higher than pre-European settlement conditions in more than 90 per cent of the river length that was assessed, and were substantially modified in at least one third of the river length assessed in every state, except Tasmania.
- In the Murray-Darling Basin, the following key observations were made:
- Ten per cent of river length was found to be severely impaired, having lost at least 50 per cent of the types of aquatic invertebrates expected to occur there.
- More than 95 per cent of the river length assessed in the Murray-Darling Basin had an environmental condition that was degraded and 30 per cent was substantially modified from the original condition.
- Most reaches in the central and western part of the Murray-Darling Basin were moderately modified.
- All groups of reaches in the Basin had disturbed catchments and modified water quality.
- Many parts of the Basin were threatened by multiple stresses, principally land use changes, damaged riparian vegetation, poor water quality, increased bedload, and modified hydrology.
- From the south-east Queensland Ecosystem Health Monitoring Program, the following key findings are apparent:
- In south-east Queensland, major changes in freshwater ecosystem health during 2004–05 were not detected.
- Natural variation appears to account for the minor changes in indicator correlations across the different years of assessment.
Assessment of river and wetland health is discussed in more detail in the following sections: