Salinity - Overview - South Australia
South Australia
Introduction
Dryland salinity affects approximately 370 000 ha of land and wetlands in South Australia, in addition to 84 000 ha of primary (or natural) salinity. Under current land use and groundwater trends this is predicted to increase by 60% in 50 years.
The largest area affected by dryland salinity in South Australia is in the Upper South East, where the rising regional watertable in the limestone aquifers of the Murray Basin is intersecting the land surface.
Estimate of salt-affected lands and risks was based on field survey at scale of 1:100 000. Projection for 2050 was based on extrapolation of field survey and groundwater trend data from representative catchments across the agricultural regions. The South Australian estimates of current extent cannot be compared directly to other States as they are better estimates of affected land than exist for the other States. The figures for 2050 are considered comparable to other State 2050 projections.
Findings
- Because most of the groundwater trends are strongly controlled by rainfall, levels have been falling throughout southern South Australia for the past two to three years due to well below average winter rainfalls with some drier catchments experiencing falling groundwater levels since 1993.
- Increasing stream salinisation is occurring in the Tod River (Eyre Peninsula) and Middle River (Kangaroo Island). Elsewhere, particularly the Mt Lofty Ranges, trends are not evident from the available data.
- Groundwater modelling suggests that vegetation clearance in the Mallee will cause salinity to increase by 115 µS/cm by 2050 at Morgan, costing consumers an additional $16.5 m each year.
- Biodiversity mapping has identified several areas at risk from rising watertables. These include extensive ti-tree shrub lands and native grasslands in the Coorong District, and seasonal wetlands and watercourses in the Upper South East. On Kangaroo Island, the viability of sedge and ti-tree ecosystems protected in conservation parks or vegetation heritage agreements are threatened by extensive areas of shallow saline aquifers, while on Lower Eyre Peninsula, native vegetation on valley floors and in seasonal swamps has been identified as being at high risk.
Key issues
- The guarantee of good quality water into the future is the major issue for South Australia. There is very limited, often no, scope to further develop water supplies within the State. Water from the Murray is essentially the only option for improved supplies apart from the more expensive option of desalinisation of salt water. Long-term guarantees from the other States in the Murray-Darling Basin are essential for South Australia.
- Managing and preferably preventing the predicted salt inflows from the cleared Mallee region in South Australia (and to a lesser extent Victoria) will be a major challenge requiring very long time leads and integrated approaches.
- Development of industries based on saline resource will require emphasis.
Reporting units and case studies
Reporting units
The results of the South Australian Dryland Salinity Assessment 2000 are reported by agricultural regions (see map and table below).
Figure: Agricultural regions of South Australia
| Region | 1982 | 1990 | 1993 |
|---|---|---|---|
| Upper Southeast | - | 60 000 | 260 000 |
| Murray Basin | - | 16 000 | 57 000 |
| Eyre Peninsula | - | 60 000 | 50 000 |
| Kangaroo Island | - | 8 000 | 10 000 |
| Mid North | - | 8 000 | 8 000 |
| Yorke Peninsula | - | 10 000 | 5 000 |
| Mt Lofty Ranges | - | 2 500 | 2 500 |
| Total | 55 000 | 224 500 | 392 500 |
What are groundwater flow systems?
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
Case studies were implemented in catchments in southern Australia as part of an evaluation of the groundwater flow systems and a catchment water balance approach to identify:
- areas of the catchment where changes in recharge will most affect catchment salinity;
- how much recharge reduction would be required to reduce salinity by a given percentage in an area of salt-affected land;
- land use and farming system options for reducing recharge enough to manage salinity;
- information for an economic analysis of the costs, benefits and viability of the options for change;
- constraints to achieving required change.
The case study catchment in South Australia was Wanilla, South Australia - a local to intermediate flow system in deeply weathered rock. Groundwater discharge at break of slope and valley floors
Further information
- South Australia 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
- Primary Industries and Resources South Australiahome page
- National Dryland Salinity Program
- National Action Plan for Salinity and Water Quality
State strategy
Government of South Australia 2000a, Directions for Managing Salinity in South Australia, Primary Industries and Resources SA.
Government of South Australia 2000b, South Australian River Murray Salinity Strategy, Department for Water Resources.
Government of South Australia 2000c, State Dryland Salinity Strategy, Primary Industries and Resources SA.
Key references
Barnett, S.R., Yan, W., Watkins, N.L., Woods, J.A. and Hyde, K.M., 2000. Murray Darling Basin Salinity Audit -Groundwater modelling to predict future salt loads to the River Murray in South Australia. South Australia. Department for Water Resources. Report Book 2000/00045.
Barnett, S.R., and Zulfic, D., (in prep). National Land And Water Resources Audit, Dryland Salinity. Assessing groundwater level trends and risk mapping in South Australia. South Australia. Department for Water Resources. Report Book.
Grear, B.P. and Moyle, G.W., (in prep). Biodiversity risk assessment from dryland salinity in South Australia. South Australia. Department of Environment and Heritage report.
Hajkowicz, S. and Young, M., 1999. Interim estimates of dryland salinity impact cost associated with agricultural land use in South Australia (using land systems mapping). CSIRO Land and Water.
Hajkowicz, S. and Young, M., 2000a. Refined interim estimates of dryland salinity impact cost (using mapping of actual areas affected). CSIRO Land and Water.
Hajkowicz, S. and Young, M., 2000b. An economic analysis and cost sharing assessment for dryland salinity management. A case study of the Lower Eyre Peninsula in South Australia. CSIRO Land and Water.
Jolly, I.D., Walker, G.R., Stace, P.M., van der Wel, B. and Leaney, R.A., 2000. Assessing the impacts of dryland salinity on South Australia?s water resources. CSIRO Land and Water, Technical report 9/00.
Stauffacher M., Bond, W., Bradford, A., Coram, J., Cresswell, H., Dawes, W., Gilfedder, M., Huth, N., Keating, B., Moore, A., Paydar, Z., Probert, M., Simpson, R., Stefanski, A. and Walker, G., 2000. Assessment of salinity management options for Wanilla, Eyre Peninsula: Groundwater and crop water balance modelling. CSIRO Land and Water, Technical Report 1/00.
South Australian Dryland Salinity Assessment 2000
Link to the Map Maker to make a map using this information.
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