Salinity in Australia
Encyclopedia
Dryland salinity
Dryland salinity is salinity that occurs in a landscape that is not irrigated, as distinct from irrigation salinity and urban salinity.-Overview:...
are two problems degrading the environment of Australia
Environment of Australia
The Australian environment ranges from virtually pristine Antarctic territory and rainforests to degraded industrial areas of major cities.- Issues :...
. Salinity is a concern in most states, but especially in the south-west of Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
.
The Eastern Mallee
Eastern Mallee
Eastern Mallee is an Interim Biogeographic Regionalisation for Australia subregion in southern Western Australia.-Geography:Eastern Mallee is roughly defined as the eastern half of the Mallee biogeographic region. It has an area of around 46,000 square kilometres, and is very sparsely populated....
and the Western Mallee
Western Mallee
Western Mallee is an Interim Biogeographic Regionalisation for Australia subregion in southern Western Australia. It is a sparsely populated subregion with an area of about 47,000 square kilometres, roughly centred on the town of Newdegate...
of Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
are areas that are prone to salinity with little remedial action being undertaken to rectify the problem. Lands surrounding Lake Bryde-East Lake Bryde
Lake Bryde-East Lake Bryde
Lake Bryde-East Lake Bryde is a DIWA-listed freshwater wetland system in Western Australia. It is located at , in the Shire of Kent, 34 kilometres south-west of Newdegate...
and Dumbleyung Lake
Dumbleyung Lake
Dumbleyung Lake, also widely known as Lake Dumbleyung, is a salt lake in Western Australia. It is located at , in the Great Southern region of Western Australia...
have also been affected.
In the Murray River
Murray River
The Murray River is Australia's longest river. At in length, the Murray rises in the Australian Alps, draining the western side of Australia's highest mountains and, for most of its length, meanders across Australia's inland plains, forming the border between New South Wales and Victoria as it...
valley irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
has caused salinity problems. Land surrounding the town of Werrimull
Werrimull, Victoria
Werrimull is a small Australian town and locality the state of Victoria and a part of the Sunraysia region. The place by road, is situated about 10 kilometres west of Karawinna and 10 kilometres east of Bambill....
in the northwest of Victoria have been affected by salinity due to land clearing.
The problem is a land management
Land management
Land management is the process of managing the use and development of land resources. Land resources are used for a variety of purposes which may include organic agriculture, reforestation, water resource management and eco-tourism projects.-See also:*Sustainable land management*Acreage...
issue, similar to severe drought in Australia
Drought in Australia
Drought in Australia is defined as rainfall over a three month period being in the lowest decile of what has been recorded for that region in the past. This definition takes into account that drought is a relative term and rainfall deficiencies need to be compared to typical rainfall patterns...
and to Australia's efforts to control exotic weeds and pests
Invasive species in Australia
Invasive species are a serious threat to the native biodiversity of Australia and are an ongoing cost to Australian agriculture.Management and the prevention of the introduction of new invasive species are key environmental and agricultural policy issues for the Australian federal and state...
, both threatening yields from agriculture in Australia
Agriculture in Australia
Australia is a major agricultural producer and exporter. Agriculture and its closely related sectors earn $155 billion-a-year for a 12% share of GDP. Australian farmers and graziers own 135,996 farms, covering 61% of Australia’s landmass. There is a mix of irrigation and dry-land farming...
.
Process
The soil in Australia naturally contains salt, having accumulated over thousand of years. This can come from prevailing winds carrying ocean salt, the evaporation of inland seas, and through the weathering of salt containing parent rocks. Rainfall absorbs this salt on the surface, and carries it down into the subsoil where it is stored in unsaturated soil profiles, until it is once again mobilised by ground water and rising water tableWater table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...
s. When this ground water comes closer to the surface, this salt is also brought up. As the water eventually evaporates, it leaves behind all this concentrated salt, resulting in soil salinity.
This can be caused by an imbalanced hydrological cycle, or by irrigation.
Prior to British settlement in 1788, groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
levels were in equilibrium
Hydrostatic equilibrium
Hydrostatic equilibrium or hydrostatic balance is the condition in fluid mechanics where a volume of a fluid is at rest or at constant velocity. This occurs when compression due to gravity is balanced by a pressure gradient force...
. Seasonal recharge, and year round utilisation of ground water by deep rooted native vegetation resulted in ground water levels remaining static.
Land clearing in Australia
Land clearing in Australia
Land clearing in Australia describes the removal of native vegetation and deforestation and in Australia. Land clearing involves the removal of native vegetation and habitats, including the bulldozing of native bushlands, forests, savannah, woodlands and native grasslands and the draining of...
has resulted in a loss of this native vegetation, replaced largely by agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
and pasture
Pasture
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep or swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...
crops. These are often annual plants and shallow rooted, and thus, unable to intercept, and adequately absorb stored, and rising ground water. This creates an imbalanced hydrological cycle, and results in dryland salinity
Dryland salinity
Dryland salinity is salinity that occurs in a landscape that is not irrigated, as distinct from irrigation salinity and urban salinity.-Overview:...
.
Salinity is classified as a dissolved salt content of a substance like soil or water. Salinity can prevent crops and other vegetation from growing leaving land empty.
Secondly, irrigation water itself can contain salts, which are deposited into the soil with its use. This level of salt can range from 0.5 - 2 tonne per hectare per year, and can greatly increase natural salt levels.
Effects and Impacts
Over time this process has caused the thin top-soil layers to become irreversibly salty, and no longer suited for agriculture. By 1999 an estimated 2.5 million hectares of land had become salinised since the introduction of European farming methods.Currently, around 5.7 million hectares of land is classed as having 'high potential' for salinisation, which that number expected to rise to 17 million hectares by 2050.
High soil salt levels have dramatic impact on plant root zones, in both native vegetation as well as agricultural and pasture crops, natural wetlands and surrounding water ways. An increase in salt can decrease the ability of plants to absorb water through their roots via osmosis
Osmosis
Osmosis is the movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration, aiming to equalize the solute concentrations on the two sides...
, cause leaf burn and necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
through increased levels of sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
and chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
, and create nutrient and ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
ic imbalances, resulting in poor growth, and death. Salinity can also adversely affect infrastructure such as roads and buildings, and underground pipes and cables through oxidation.
Muehlenbeckia horrida subsp. abdita
Muehlenbeckia horrida subsp. abdita
Muehlenbeckia horrida subsp. abdita, commonly known as Remote Thorny Lignum, is a critically endangered shrub endemic to Western Australia.-Description:...
, commonly known as the Remote Thorny Lignum, is a critically endangered species due to its intolerance to salinity.
New South Wales
Currently,5% of New South WalesNew South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
is affected by dry land salinity, and around 50% under threat.
15% of current irrigated land is impacted, and up to 70% is currently under threat.
The main regions currently affected, and at high risk are The Murrumbidgee River catchment near Griffith, and Jemalong river Catchment near Forbes, as well as the Murray river irrigation area near Deniliquin.
However new South Wales is barely impacted at all by saliity compared to the other states of Australia.
Victoria
The current levels of salinity in VictoriaVictoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
are relatively small, with the main impact expected to occur in high risk areas in the coming years.
These high risk areas include the Campaspe, Loddon, Corangamite, Glenelg-Hopkins, Goulburn-Broken catchments, and Wimmera and Mallee regions.
The current cost to Victoria is estimated at $50million per year. This is expected to rise significantly with the impacts on agricultural land, wetlands and infrastructure in high risk areas to increase, mainly in part to an anticipated 10 fold increase in salt levels by 2050.
Western Australia
Western AustraliaWestern Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
contains the majority of land affected by salinity in Australia, with around 70%.
Over 2 million hectares are currently affected, and around 4 million hectares of land are currently listed as high risk, and 50% of divertible water is already considered overly saline.
By 2050, 450 plant species are expected to be extinct
75% of water bird species in decline, a 75% reduction in sealed road life, and $400million in lost profits.
South Australia
Salinity in South AustraliaSouth Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
is a problem in all principle agricultural areas, with 370000 hectares of land and wetlands impacted. At current rates, this is expected to increase by 60% by 2050.
It is expected to cost the state around $47million per year in lost agricultural profit, and is expected to taint more than 20% of ground water to levels above those safe for human consumption.
Tasmania
TasmaniaTasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
is relatively unaffected by salinity, with around 1% of agricultural land, and 8% of farm land adversely affected by salt, resulting in a current cost to the state of around $5million per year, rising to around $13million by 2050. The majority of this salinity is irrigation based.
Queensland
QueenslandQueensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
is the least affected state of Australia, due to its unique seasonal rainfall. Around 15000 hectares are currently affected, with 3.1million hectares considered highrisk.
At current rates however, salinity is predicted to have moderate scale impacts on land and infrastructure by 2050, with 12,000km of roads, 1500km of rail lines, and around 2.8million hectares of agricultural land, remnant vegetation, and wetlands and streams negatively affected
Government initiatives
The Australian governments have taken an integrated approach to target different scales of management. The approach is to manage the salinity issue at national, regional and state levels, down to local and individual farmers. Since 1983 the Australian governments have actioned the National Soil Conservation Program, National Landcare Program, Natural Heritage TrustNatural Heritage Trust
The Natural Heritage Trust was set up by the Australian Government in 1997 to help restore and conserve Australia's environment and natural resources....
, National Action Plan for Salinity and Water and Caring for our Country.
The National Landcare Program focused on improving resource management and practices at the farm and local level. The National Dryland Salinity Program (1993 to 2000), funded a broad range of research and development from which to roll out further government programs.
The National Action Plan for Salinity and Water Quality (NAPSWQ), implemented together with the Natural Heritage Trust
Natural Heritage Trust
The Natural Heritage Trust was set up by the Australian Government in 1997 to help restore and conserve Australia's environment and natural resources....
(NHT) program, ran from 2000 to 2008. The NAPSWQ was adopted through an intergovernmental agreement between Australian commonwealth, state and territory governments. The plan aimed to help support community action and land managers in adversely affected catchments, and was rolled out by regional Natural Resource Management (NRM) organisations. The governments committed $1.4 billion over seven years to tackle the salinity problem. The plan involved input and participation from government, community, local business and land managers. The NAPSWQ focused on 21 regions across Australia that were deemed; through hazard assessments and dryland salinity
Dryland salinity
Dryland salinity is salinity that occurs in a landscape that is not irrigated, as distinct from irrigation salinity and urban salinity.-Overview:...
risk, to be most affected by salinity and water problems. The goal of the NAPSWQ was to motivate and enable regional communities in preventing, stabilising and reversing trends in salinity; improve water quality and secure reliable allocations for both human, industrial and environment use. The overarching objectives of the NHT were biodiversity conservation, sustainable use of natural resources, community capacity building and institutional change.
The final report for the NAPSWQ states that ‘With few exceptions the massive efforts involved in delivering NAPSWQ and NHT programs have at best halted the degradation of these resources. This has reinforced the view of the State of Environment
State of the Environment
The term State of the Environment normally relates to an analysis of trends in the environment of a particular place. This analysis can encompass aspects such as water quality, air quality, land use, ecosystem health and function, along with social and cultural matters.- The Pressure-State-Response...
(SoE) Report that concluded that the condition of these resources continues to decline despite the best efforts of the community and government'.
In 2008 the initiative Caring for our Country was started to replace the National Action Plan, which had ceased. This Australian Government initiative aims to build on the work done under the NAPSWQ, focusing on a more targeted asset-based approach, and aims to build attitudes of environmental stewardship.
Case Study Examples
Salinity management in the Murray-Darling Basin has included investment in salt interception schemes, rehabilitation of irrigation areas, and programs to educate landholders and irrigators on better practicesIn the South-west rivers region of Western Australia, salinity impacts on potable and irrigation water supplies, and the areas unique biodiversity. Outcomes of NRM programs in Western Australia include re-vegetation, fencing, soil treatment, drainage works, treatment for soil erosion, monitoring programs, support of community projects, training, conservation agreements and a Strategic Tree Farming project.
Tasmania faces different salinity management issues due to its unique topography. Under the Caring for our Country Project Tasmania has set up demonstration farm sites which test management strategies of surface and sub-surface drainage, and trees planting to intercept water, and salt tolerant plant species.
Best management practice
There is no clear agreement about what constitutes best management practice for salinity in Australia. While there are a range of techniques and strategies available, success is often varied from one context to the next; there is no simple solution. Location, time frame and personal circumstances may all influence the effectiveness of particular options.Possible management strategies include:
- The use of salt-tolerant plants, such as:
- Atriplex amnicolaAtriplex amnicolaAtriplex amnicola, commonly known as river saltbush or swamp saltbush, is a species of shrub in the Amaranthaceae family. Endemic to Western Australia, it is native to the floodplains of the Murchison and Gascoyne Rivers....
- Saltgrow - a hybrid gum tree being utilized within Australia to try to reverse damage within affected high-salinity areas. The tree has been highly successful, and has been attributed to be able to completely remove salinity within damaged areas and allowed new grasses and shrubs that are not salt resistant, to grow.
- Atriplex amnicola
- The use of perennial crops and pastures
- Engineering responses including deep drainage and pumping (to lower groundwater)
- Reverse banks and interceptor banks (to divert surface water)
- Revegetation with native species
- Establishing trees
- Preventing further clearing in vulnerable areas
A number of organisations are seeking ways to reduce the impact of salinity on Australian agriculture, including the Cooperative Research Centre for Plant-Based Management of Dryland Salinity. Greening Australia
Greening Australia
Greening Australia is an Australian environmental organisation, founded in 1982, the International Year of the Tree, to protect, restore and conserve Australia's native vegetation...
and Australian Centre for Plant Functional Genomics
Australian Centre for Plant Functional Genomics
The Australian Centre for Plant Functional Genomics is a research organisation focusing on improving the resistance of wheat and barley to hostile environmental conditions, using functional genomics technologies....
have also implemented projects to alleviate salinity in Australia.
Community-based management strategies
Community-based approaches have been a key feature of many regional salinity management programs in Australia. This is in response to various government initiatives, notably the National Landcare Program (1989), Natural Heritage TrustNatural Heritage Trust
The Natural Heritage Trust was set up by the Australian Government in 1997 to help restore and conserve Australia's environment and natural resources....
(1997) and the National Action Plan for Salinity and Water Quality (2000).
This approach provides the social platform required in many cases for the successful adoption of salinity management practices. Often lacking however, is the presence of scientific skills and detailed knowledge needed to develop viable technical and economic salinity management options. It is also suggested that community-based approaches may reinforce existing power structures, disadvantaging those who are already marginalised when making decisions about salinity management.
Below are some examples of community-based programs currently operating in Australia and their contributions to salinity management.
Landcare
Landcare groups involve community members and landowners work together in a voluntary capacity to improve land management practices. In relation to the management of salinity, these groups have been effective in: raising awareness and educating the community about dryland salinity; allowing local knowledge and information to be shared in order to develop suitable management plans; developing skills, building capacity and empowering communities to address salinity issues.Saltwatch
Established in Victoria in 1987, Saltwatch is an ongoing community- and school-based program focused on monitoring salinity levels in Australian waterways. Students, teachers and community members are involved in collecting water samples from their local area, conducting salinity tests and recording this data. It is an effective educational tool that provides opportunities for partnerships to be developed between government agencies and the wider community, however it is not necessarily linked directly to the implementation of salinity management strategies.Climate change and its impact on salinity
There are mixed predictions in relation to climate changeClimate change in Australia
Climate change has become a major issue in Australia due to drastic climate events since the turn of the 21st century that have focused government and public attention. Rainfall in Australia has increased slightly over the past century, although there is little or no trend in rainfall in northeast...
’s effect on salinity in Australia. Climate change can be seen to appease salinity in Australia in some circumstances, but in others it may have detrimental effects. It is predicted that in some instances climate change will result in the reduction in annual rainfall leading to a drier and warmer climate, which will ultimately reduce salinity. Conversely climate changes impact on the salt concentration in water bodies is expected to be unfavourable.
Where there is a reduction in rainfall it is expected that salinity will be reduced. This will occur as a result of the water table being recharged less often, reducing the chance of the water table transporting underground salts to the surface of the land. Climate change may also result in the offsetting of rainfall into different seasons, resulting in larger down pours and extreme weather events in some locations within Australia. In these instances as evaporation will not occur at a faster pace than rainfall, it is likely to result in excessive additions to aquifers, which is also known as deep drainage. This is an issue as dryland salinity is onset by additional deep drainage. In Australia this will be most evident in South Australia, Victoria and the lower half of Western Australia. However these changes are expected to be minimal as the water table may already be reduced from excessive periods of drought.
On the other hand the reduction of water in streams, rivers, water bodies and the like is likely to result in an increase of salt concentration in these water bodies. This will be particularly evident in groundwater flow systems of different catchments. Austin et al. of CSIRO have predicted that water in the Murrumbidgee will drop by up to approximately 48% by 2070 which will result in salt yields on the surface of the land falling by approximately 30%, however the stream salinity concentrations are predicted to increase by 11%.
See also
- Conservation in AustraliaConservation in AustraliaConservation in Australia is an issue of state and federal policy. Australia is one of the most biologically diverse countries in the world, with a large portion of species endemic to Australia...
- Fauna of AustraliaFauna of AustraliaThe fauna of Australia consists of a huge variety of animals; some 83% of mammals, 89% of reptiles, 90% of fish and insects and 93% of amphibians that inhabit the continent are endemic to Australia...
- Geography of AustraliaGeography of AustraliaThe geography of Australia encompasses a wide variety of biogeographic regions being the world's smallest continent but the sixth-largest country in the world. The population of Australia is concentrated along the eastern and southeastern coasts...
- Salinity controlSalinity controlSoil salinity control relates to controlling the problem of soil salinity and reclaiming salinized agricultural land.The aim of soil salinity control is to prevent soil degradation by salinization and reclaim already salty soils...