In this section, the major surveys of the salinity threat are discussed. Predictions based on groundwater trends, field surveys and landscape characteristics indicated that unless effective solutions are implemented, the area could increase to 17 million hectares by Most is agricultural land more than 11 million hectares :.
Table 1. Areas ha with a high potential to develop dryland salinity in Australia [12]. Over four million hectares have areas at risk, which could double the existing area affected by salinity by Further, the report noted the finding of an existing salinity hazard assessment for the Northern Territory Tickell b that the overall hazard for the Territory was relatively low. As a result, the Audit did not conduct further assessment of the NT.
However, it was acknowledged that dryland salinity could become a problem for many catchments with high salt stores if water balance changes led to groundwater rises. The Audit concluded that the extent of salinity in northern Australia could be minimised by prev entive management. The Audit report outlined on-farm and broader impacts:.
The main impact of increasing salinity at the farm level is loss of production and income. Other on-farm effects include the decline in capital value of land, damage to infrastructure, salinisation of water storage, loss of farm flora and fauna, and loss of shelter and shade.
These effects are magnified at the regional level, where they have a substantial impact on public resources such as biodiversity, water supplies and infrastructure. Table 2. Summary of assets in areas at high risk from shallow watertables or with a high salinity hazard [18]. Notes : 1 Data from all States, Qld only for The report suggested that these different results are most likely the consequence of different concepts, assessment methods and coverage used in each study.
Information on all salinity, not just dryland salinity as in the other studies, was collected. Table 3. Area affected by salinity, comparison of survey results with other estimates [22]. In response to Committee questioning on the current extent of salinity, he commented:. I think there are different ways of measuring salinity and salinity threat. Each has its strengths and limitations, and calibration between the different methods is also not the easiest thing to do, so to base a conclusion on one type of measurement is perhaps a little bit open to question.
I think the temporal aspect is also really critical. Taking a snapshot of a particular time does not really give you much information. You need to measure it over a period to see what the trend is, to establish if it is increasing or decreasing.
I think that will tell you what is really happening. But I repeat that each of the techniques that is used to measure has its strengths and weaknesses, and we have got to recognise that.
It notes that the risk assessments conducted across the states were based on a range of factors and that the data available on each of these factors was highly variable. The paper concludes that the Audit figures were considerably overestimated. He went on to say that 'the science that underpins those sorts of assessments has continued to be worked on' and, in light of this, information and figures are in the process of being updated.
It is actually confined to some specific parts of the landscape. I think it is fair to say that, with increasing knowledge, it seems the picture may be a little more optimistic than we thought from the first review of salinity risk provided by the National Land and Water Resources Audit. For instance, I believe that, while the aggregate figures in the projections for salinisation in the wheat belt of Western Australia are still remarkably high, they have come down somewhat from the projections that were published in or from that work.
With better understanding, we are also seeing the mechanisms of salinity and understanding them better. He also noted that salinity still presents a major environmental and economic challenge:. Ground water levels have been depleted by drought, and you can see that there is a large seasonal and interseasonal component, no doubt, in ground water levels and the salinity that has been expressed. The impacts of salinity have been disguised somewhat by drought over the period.
So what is actually happening in an underlying way is probably more severe than what we are observing. But I think by any calculation we are still faced with a major threat to our biodiversity, our agriculture and our civic infrastructure across the country. I do believe there is a grave risk that we are thinking that salinity is all over because we have had a series of dry years, particularly on the east, but not only there.
One of the things that we know from the National Dryland Salinity Program is that some of these ground water systems are very sluggish. There needs to be ongoing assessment of the impacts of climate change on the future extent and risk of dryland salinity.
The Department for Environment and Water acknowledges Aboriginal people as the First Peoples and Nations of the lands and waters we live and work upon and we pay our respects to their Elders past, present and emerging. We acknowledge and respect the deep spiritual connection and the relationship that Aboriginal and Torres Strait Islander people have to Country. The Department works in partnership with the First Peoples of South Australia and supports their Nations to take a leading role in caring for their Country.
Acknowledgement of Country The Department for Environment and Water acknowledges Aboriginal people as the First Peoples and Nations of the lands and waters we live and work upon and we pay our respects to their Elders past, present and emerging. Topics Land and soil Soil degradation Salinity Salinity Discover the effects, types and causes of salinity, how long it takes to happen and fix, and answers to common salinity questions.
Slide controls:. Where does the salt come from? Salt that accumulates in soil can come from a number of sources: Rainfall — airborne salts from ocean spray and pollution are dissolved in atmospheric moisture and deposited on the land when it rains. Weathering — minerals that make up rocks break down and release ions that are able to form salts.
Aeolian deposits — wind picks up and transports dust and salt from soil and lake surfaces and redistributes it across the landscape.
Connate salt — during deposition, salt has been incorporated into marine sediments, or in areas of internal drainage, salt has accumulated over geologic time due to transport and evaporative processes.
These areas may later become sources of salt. Page last updated 30 July The following buttons will open a feedback form below Was this page helpful? Yes No. Thank you for your feedback. Would you like to tell us more? Australia is facing an environmental problem that could, and very likely will, bring our economy to its knees, if we continue to ignore it the way we have in the past. We have known about it since , but only since the s have we seriously tried to understand it and combat it.
Now it's accelerating, and we may have already lost the battle. Although Australian native trees are used to high salt conditions, they cannot survive when salt is brought near the surface by rising water tables. Dryland salinity, the gradual loss of farm and grazing land to rising salt, is a massive problem, hard to comprehend and harder still to stop. There is salt everywhere in Australia; vast amounts of it, mostly located underground. It has built up over many thousands of years, originating from the weathering of rock minerals or the simple act of sea salt dropping via rain or wind.
The native Australian vegetation evolved to be salt-tolerant. Many of the woodland species, for example, have deep roots and a high demand for water.
Whilst the system was in balance, the salt stayed put. But when European farming arrived and replaced the natives with crop and pasture plants that have shorter roots and need less water, the inevitable happened. With every fall of rain, unused water "leaks" down to the water table, raising it, and bringing the salt up with it.
That process continues today, and the volumes of water and salt are vast. Under the soils of the Western Australian wheatbelt and some parts of eastern Australia the salt store is so immense, and the movement of sub-surface water so slow, that restoration to fertility of salt-effected land will take generations. Some areas may never recover. It is a tragic irony that the felling of many billions of trees to make room for the farming that let this nation prosper has caused, in just years, our worst environmental crisis, and destroyed a natural balance that had existed for millenia.
Now farmers are frightened as they watch their farms degrade, billions of dollars are being lost, and scientists are admitting for the first time that there are no practical answers yet.
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