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Indicator: LD-06 Area and proportion of land affected by dryland salinity and acidity

Data

Area of Australia currently affected by dryland salinity (or, rather, currently affected at the time when data was compiled for the NLWRA) is difficult to estimate as states use varying methodologies for deriving their estimates and some states do not provide estimates of area affected, only area at risk. On the basis of the data provided to the Audit, state areas currently affected by salinity are:

• New South Wales salinity 
• Victorian Dryland Salinity Assessment 2000 
• Queensland salinity 
• South Australian salinity 
• WA Salinity at a glance 
• Tasmanian salinity 
• Northern Territory - salinity 

Source: Australian Dryland Salinity Assessment 2000, Dryland Salinity by State.

• Australian Dryland Salinity Assessment 2000. Extent, impacts, processes, monitoring and management options (Word - 46 KB) 

What the data mean

Approximately 5.7 million hectares are within regions mapped to be at risk of or affected by dryland salinity. It is estimated that in 50 years' time the area of regions with a high risk may increase to 17 million hectares.

Some 20 000 km of major road and 1600 km of railways occur in regions mapped to have areas of high risk. Estimates suggest these could be 52 000 km and 3600 km respectively by the year 2050.

Up to 20 000 km of streams could be significantly salt affected by 2050.

Areas of remnant native vegetation (630 000 ha) and associated ecosystems are within regions with areas mapped to be at risk. These areas are projected to increase by up to 2 000 000 ha over the next 50 years.

Data Limitations

No new continent-wide data to assess whether the area of land currently affected or at risk of salinity has increased or decreased has been collected.

Issues for which this is an indicator and why

Land — Land condition - Hydrology 

Dryland salinity in Australia has significant implications for the condition of terrestrial biodiversity. Australia’s soils are naturally saline, but perennial deep-rooted vegetation helps prevent salt from surfacing. Removal of this vegetation allows the salt to surface and, having surfaced, its presence there can prevent vegetation from re-establishing.

The problem is compounded by the high acidity/ low alkaline condition of the soils.

Change in area affected is a straightforward indicator of change of land condition resulting from salinity.

Other indicators for this issue:

• IW-26 Forested streamlength 
• IW-05 Average annual groundwater depth 
• BD-14 Examples of impacts of changed hydrology on biodiversity 

Land — Direct pressure of human activities on the land - Salinity 

Extent of dryland salinity and acidity is an indicator of the area of land under pressure from salinity.

Other indicators for this issue:

• IW-05 Average annual groundwater depth 
• IW-26 Forested streamlength 

Land — Contributions and pressures between the land and inland water - Pressures of changes to inland waters on land 

Surface salinity results from the rise of saline groundwater into surface soil. Extent of surface salinity is an indicator of the pressure of salt from rising groundwater on the land.

Other indicators for this issue:

IW-26 Forested streamlength 

Land — Contributions and pressures between the land and inland water - Pressures of changes to the land on inland waters 

Extent of surface salinity is an indicator of the potential pressure of saline run-off from the land on inland waters.

Other indicators for this issue:

• LD-04 Area and change in area of exposed soil surface contributing to erosion 
• IW-12 Catchment nitrogen and phosphorus load 
• IW-13 Catchment sediment load 
• IW-26 Forested streamlength 
• HS-41 Water consumption by sector 

Land — Contributions and pressures between the land and inland water - Condition of species at the land-inland waters interface 

Extent of surface salinity is an indicator of the potential pressure of salinity either on riverbanks or in surface waters on species living at the land-freshwater interface.

Other indicators for this issue:

• IW-26 Forested streamlength 
• IW-33 Abundance and distribution of waterbirds 

Biodiversity — Pressures on biodiversity - Changed hydrology 

Area of land affected by dryland salinity is a surrogate indicator for extent of disturbance of biodiversity by dryland salinity.

Other indicators for this issue:

• BD-14 Examples of impacts of changed hydrology on biodiversity 
• IW-05 Average annual groundwater depth 
• IW-06 Average annual groundwater pressure 
• IW-10 Assessment of river condition indices 
• IW-26 Forested streamlength 
• IW-27 Extent of significant wetlands (incl. Ramsar) 
• IW-28 Number of effective fishways 
• IW-33 Abundance and distribution of waterbirds 
• IW-46 Implementation of COAG principles 

Further Information

• Salinity on Australian Farms (PDF - 1100 KB)