Salinity - Overview - Queensland
Queensland
Introduction
The area estimated to be affected by dryland salinity in Queensland is 48 000 ha. This area does not include all land with groundwater levels within 2 m of the surface. Affected land is distributed throughout the eastern part of the State with only minor occurrences in western Queensland.
The Condamine-Balonne and Border Rivers catchments are the only catchments in the State where sufficient data exist to determine, on a catchment-wide basis and with a moderate level of accuracy, the area with groundwater levels within 2 m of the surface (some 17 500 ha).
Although little data are available on which to base future water level trends over most of the State, a salinity hazard map indicating land potentially at risk of developing salinity has been produced. There is a wide distribution of land with a high salinity hazard. Known areas of distribution are in the Murray-Darling, the Burnett and Fitzroy regions.
The hazard map was produced by collating available datasets for geology, Atlas of Australian Soils, elevation, land use change and potential excess rainfall. It reflects potential dryland salinity areas related to the extent of land use change. There are no State-wide data which capture salt storage in the weathered landscape zone. This factor must be taken into consideration in tropical areas where most of the salt has been flushed from the system. The index-overlay approach used to derive areas affected by dryland salinity provides an estimate of ?equilibrium? or ?worst-case? scenarios with the assumption of no change in land use or management. As a result a significant overestimation of areas at risk is likely to have been made. It should not be directly compared with 2050 predictions using the groundwater trend approach.
Estimates of projected dryland salinity hazard in 2050 were based on a map overlay analysis using attributes that drive salinisation such as geology, landscape features, regolith depth and type, land use and climate. Groundwater data for assessing salinity risk in Queensland are extremely limited. Groundwater trend analysis was possible only in Condamine-Balonne and Border Rivers catchments of the Murray-Darling Basin. The estimate of area affected (48 000 ha) by dryland salinity was based on field observation in the early 1990s, and workshop-based consultations. Information has been prepared at a scale of 1:2 500 000.
Findings
Although Queensland has an extensive groundwater monitoring network for management of groundwater extraction, the network was not designed for monitoring the shallower groundwater systems that are associated with dryland salinity processes. Hence there are very limited groundwater condition and trend monitoring data to assess and predict dryland salinity processes and impacts.
- A total of 3.1 million hectares are considered to have a high salinity hazard; and 2.6 million hectares are in agricultural lands.
- Where groundwater trend modelling was undertaken in the Condamine-Balonne and Border Rivers areas, 373 000 ha are predicted to have groundwater levels within 2 m of the surface by 2050.
- Only a very small length of roads has been specifically identified as having deteriorated as a direct result of salinity but approximately 12 000 km of roads are in the areas of high hazard.
- An increase in salinity in streams has been noted in parts of the Condamine, Lockyer Creek, the lower Mary, the South Burnett, Three Moon Creek and some tributaries of the Fitzroy.
- The Ramsar-listed wetlands in Queensland are predominantly tidal and it is expected that coastal-related processes will dominate the future health of these systems.
- No costing of the effect of salinity has been undertaken. Most outbreaks are small, localised and are not considered of serious economic consequence to agricultural land at this stage.
- Impacts on wetlands and riparian zones have not been assessed.
Key issues
- Current monitoring networks do not provide a suitable framework for assessment of dryland salinity and its impacts in Queensland. There is an urgent need to establish a State-wide monitoring network of groundwater, surface water, key land use and biodiversity parameters to better inform managers of the trends and implications of dryland salinity.
- It is vital that preventive and protective action is taken in maintaining water balance for those areas where salt stores would be mobilised with the clearing of native vegetation.
- Work is required to develop and then implement farming systems that deliver sustainability and production outcomes, particularly taking into account long-term risks of watertable rise in salinity.
- The index-overlay approach generated a ?salinity hazard? map for Queensland. However, the approach does not provide an assessment of trends in dryland salinity. Based on our understanding of salinity processes and groundwater flow systems, the method does provide a sound basis for prioritisation of salinity research and development activities.
- The lack of available data limits the capacity to provide a State-wide salinity risk assessment that would underpin at fine scales regional and property planning processes for vegetation management. Nevertheless, for selected catchments in the Murray-Darling Basin where 1:25 000 scale data are available, this is possible and of priority.
Reporting units and case studies
Reporting units
The hazard map was produced by collating available datasets for geology, Atlas of Australian Soils, elevation, land use change and potential excess rainfall. It reflects potential dryland salinity areas related to the extent of land use change. There are no State-wide data which capture salt storage in the weathered landscape zone. This factor must be taken into consideration in tropical areas where most of the salt has been flushed from the system. The index-overlay approach used to derive areas affected by dryland salinity provides an estimate of 'equilibrium' or 'worst-case' scenarios with the assumption of no change in land use or management. As a result a significant overestimation of areas at risk is likely to have been made. It should not be directly compared with 2050 predictions using the groundwater trend approach.
To understand salinity across the Australian landscape and through time, we need to understand how groundwater systems respond to changing recharge, and how the excess water that results from increased recharge is distributed. The broad distribution of groundwater flow systems in Australia has been mapped using attributes such as elevation, landscape form and geology. The classification groups groundwater systems with similar recharge and flow behaviour, and other measures such as length of flow paths through aquifers, aquifer permeability and driving pressure gradients for groundwater flow. It identifies groundwater flow systems where particular management activities will lead to similar responses and provides a framework for action.
For more detail: move to the Australia?s Groundwater Flow Systems overview
Further information
- Queensland Dryland Salinity Assessment 2000 report
- Australian Dryland Salinity Assessment 2000 report
- National Technical Overview Report of the State-based dryland salinity assessments
- Australian Groundwater Flow Systems Report
- Queensland Department of Natural Resources
- National Dryland Salinity Program
- National Action Plan for Salinity and Water Quality
Link to the Map Maker to make a map using this information.
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