Australia State of the Environment Report 2001 fact sheet
Department of the Environment and Heritage, February 2002
What is happening overall?
Since 1996, an estimated additional 500 000 hectares of land has become salt affected, and the common cause is changes to water tables largely as a result of inappropriate land use in the last 200 years.
The $1.4 billion National Action Plan on Salinity and Water Quality in Australia, announced in October 2000, aims to develop a national response to this problem.
What is dryland salinity?
Australia is an ancient, weathered land with dissolved natural salt beneath the surface of vast areas of the continent. Mostly that salt sits deep in the soil and does not affect plants. Dryland salinity is caused when a rising water-table brings natural salts in the soil towards the surface. The salt remains in the soil and becomes progressively concentrated as the water evaporates or is used by plants.
Changes to landuse since European settlement, such as clearing forests and replacing deep-rooted native vegetation with shallow rooting crops and pastures, can lead to rising water-tables.
Irrigation salinity occurs when irrigation water soaks through the soil area, adding to the existing water. The additional irrigation water causes the water-table to rise, bringing salt to the surface.
What are we doing about salinity?
Addressing salinity is a huge national challenge. The Commonwealth and state and territory governments have agreed on the National Action Plan for Salinity and Water Quality. It is based on concentrated action by governments and regional communities, supported by the application of scientific advances in mapping salinity, targeted tree planting and new cropping systems to manage salinity and water quality.
The Action Plan builds on activities funded through the Natural Heritage Trust, state and territory strategies and the Council of Australian Government's Water Reform Framework The Action Plan will be implemented on a regional basis and will address a range of targets and standards for natural resource management. These targets include salinity, water quality, water flows, and in-stream and terrestrial biodiversity.
The Action Plan acknowledges that land clearing in areas at risk of salinity is a primary cause of dryland salinity. It indicates that effective controls on land clearing are required in each jurisdiction, and states that:
- any Commonwealth investment in catchment or regional plans will be contingent upon land clearing being prohibited in areas where it would lead to unacceptable land or water degradation; and
- the Commonwealth will require agreement from relevant states and territories (particularly Queensland, New South Wales and Tasmania) that their vegetation management regulations are effectively used or, where necessary, amended to combat salinity and water quality.
How is salinity such a big problem?
If nothing is done now, within 20 years Adelaide's drinking water is predicted to fail World Health Organisation salinity standards in two days out of five.
Salinity turns top quality agricultural land into a wasteland. It destroys the livelihood of farmers - and of others who supply the farmers with goods and services or who add value to farm products or who export farm products.
How big is the problem?
For every 5,000 hectares of land visibly affect by dryland salinity, the economic impact will be approx $1 million annually. If nothing is done salinity will cost $1 billion a year by 2100.
It is estimated that at least 2.5 million hectares of land are already affected by salinity. This is five per cent of our cultivated land.
The National Land and Water Resources Audit estimates that some 5.7 million hectares of agricultural and pastoral land have a high potential for developing dryland salinity through shallow water-tables. This figure could rise to 17 million hectares by 2050 if effective controls are not implemented.
Currently 630,000 hectares of native vegetation are at risk from salinity. This could increase by up to 2 million hectares over the next 50 years.
Preliminary findings from a four-year biological survey of the Western Australian agricultural zone indicate that salinity threatens the survival of 450 native plant species. Salinity has killed trees and shrubs in many wetlands in the wheat belt, and this in turn has caused a 50% decrease in the number of waterbirds using them. If all wetlands in the wheat belt become saline, well over 200 aquatic invertebrate species will become regionally extinct.
Salinity damages roads and buildings, and imposes large costs on many communities.