Agriculture, in Australia and globally, depends on access to regular supplies of water.
Faced with increasing competition for often-scarce water supplies, farmers must find ways to stay productive and profitable while reducing their water footprints, sharing collective water resources more effectively, and maintaining the health of waterways, wetlands and groundwater supplies.
Water resources in Australia
Theoretically, water is a renewable resource but Australia’s water supplies are more limited than those of many other countries.
Rainfall levels vary widely across regions, seasonally and from year to year. The country’s northern regions experience wet and dry seasons, with ‘the wet’ characterised by monsoonal rains and cyclonic activity, and sometimes, flooding, and ‘the dry’ often just that.
El Nino and La Nina weather events also impact on water supplies. El Nino events typically occur every four to seven years for 12-`8 months but have been more frequent in recent years, precipitating droughts. The frequency of storms, heavy rainfall, hail and floods has also increased over the past decade, possibly a result of climate change.
Waterways, wetlands and groundwater supplies are affected by Australia’s geography and geology, variable rainfall, and increasing water use (primarily by the agriculture sector), with resulting water quality issues from run-off and other pollutants, algal overgrowth and salinity. Reclaiming salt or brackish water through desalination is possible but costly.
Even when regions are not officially in drought, water scarcity is a huge issue for farmers in many parts of Australia, especially affecting those with large water consumption needs.
Agricultural water use
According to recent ABS data on national water use, the agriculture sector is Australia’s largest user of water and the vast majority of water used on-farm is for irrigation.
The ABS figures show that in 2012-2013, water use on Australian farms increased by nearly a third (32 per cent) from the previous year, to a total of 11.9 million megalitres. Of this, 93 per cent (11.1 million megalitres) was used for irrigation, primarily for grain and cereal crops, cotton, sugar cane; vines and horticulture.
Forty-three per cent of the water used on Australian farms in 2012-2013 (5.1 million megalitres) comes from irrigation channels; a further quarter (2.9 million megalitres) is sourced from rivers, creeks and lakes. Substantial amounts of water are also contained in the soil and stored in dams and tanks.
Irrigated crops are profitable but when water supplies are scarce, restrictions affect the productive capacity of irrigation-intensive crops such as rice and cotton. When water allocations are reduced, farmers often have no choice but to scale down production.
Most of Australia’s irrigated crops are located in the vast Murray-Darling Basin. According to the ABS data for 2012-2103, more than two-thirds (72 percent) of all Australia’s agricultural water consumption – 8.6 million megalitres – was by growers in the Murray-Darling Basin.
As a result, the region’s water supplies are under increasing pressure. The Australian Government’s Murray-Darling Basin Plan aims to restore the health of the Basin's rivers and wetlands while supporting communities and sustainable food production in the region.
The government’s national Sustainable Rural Water Use and Infrastructure Program (SRWUIP) aims to ‘bridge the gap’ between sustainable diversion limits under the Murray-Darling Basin Plan and agricultural needs. The SRWUIP has three principal components: irrigation infrastructure projects to improve on-farm delivery systems and help irrigators use water more efficiently; water purchase, through the Restoring the Balance in the Murray-Darling Basin Program; and supply measures.
Water savings generated by these projects are shared between the government (for environmental use) and irrigators (for consumption).
Under the SRWUIP, works are conducted to improve the ecological health of Australia’s waterways, restoring natural flows and changing river operations to enable better environmental outcomes with less water use.
The Australian Government has committed up to $265 million to the South Australian Government to administer the South Australian River Murray Sustainability Program, which aims to secure and return an annual long-term average of 36 gigalitres of ‘gap-bridging’ water to the Commonwealth for environmental use.
The program provides:
- $80 million to improve irrigation efficiency;
- $40 million for a South Australian water purchase program;
- $120 million to assist the irrigation industry; and
- $25 million for regional economic development.
Having access to water of adequate quality in sufficient quantity is essential to agriculture, the environment and life itself. Often, the focus is on available water volumes but water quality is equally important as it determines whether the available water is suitable for particular purposes.
Land use can impact water quality significantly. Managing the quality of our collective water resources requires a catchment-based approach and a concerted effort by all users, including agriculture, mining, communities and government.
The National Water Quality Management Strategy (NWQMS) sets national guidelines regarding water management and provides information and tools to help communities manage water resources so as to meet current and future needs. The strategy includes a step-by-step approach to planning, implementing and managing water quality, and information about common environmental stressors.
Water Quality Improvement Plans (WQIPs) identify the most cost-effective and timely projects for investment.
The Department of Environment’s Tasmanian River Catchment Water Quality Initiative builds on existing river catchment auditing and monitoring work, to provide information on pesticide use and the potential impacts of pesticide pollution on the environment, human health and industry.
Salinity, a measure of the content of salts in soil or water, can be ‘primary’ – the natural distribution of salt in a landscape – or 'secondary’, in which additional salt enters the groundwater system as a result of altered land management practices (such as widespread clearing of vegetation, poor land use and irrigation) that result in salt being transported to the soil surface and into waterways.
Excessive amounts of dissolved salt in water can negatively impact agriculture and ecosystem health. Salinity is a significant problem in south-western Australia and in some parts of the Murray-Darling Basin.
Secondary salinity may take the form of:
- dryland salinity’, which occurs when deep-rooted native vegetation is cleared or replaced with shallow-rooted plants that use less water, raising the water table and bringing salt to the surface, where it stays when the water evaporates, and
- irrigation-induced salinity, the result of excess water applied to crops that travels past the root zone into groundwater, raising the water table and bringing salt to the surface.
Salt can also be transported across groundwater systems.
Impacts of salinity
High concentrations of salt are damaging to the environment, leading to loss of native vegetation and dominance by salt-resistant species that lead to declines in biodiversity and ecosystem imbalances.
Salinity also negatively affects agriculture, infrastructure and the economy. Reduced groundcover leaves soils vulnerable to erosion, waterways can become clogged with sediment, making the water they transport unsuitable for human and animal consumption and threatening high -value ecosystems.
The impacts of salinity – reduced yields in salt-intolerant crops; the need for additional water treatment; and replacement of corroded farm machinery and infrastructure (roads, bridges, fences) – can be costly, so it’s crucial that salinity be managed, individually and collectively.
Due to the complex nature and scale of salinity, a mix of responses is required. In Australia, measures have already been introduced by government to help:
- maintain the health of wetlands;
- restore vegetative ground cover, planting native species that control the surfacing of salt;
- reduce drainage by planting crops; and
- establish ‘salt interception’ schemes to divert saline water into evaporation basins.
Farmers may also benefit from employing more efficient farming, irrigation and drainage methods, and from redesigning irrigation systems with greater consideration of the timing, volumes and locations of irrigation.
The National Water Quality Management Strategy, which involved input from all states and territories, details methods for reducing salinity and adapting irrigation practices.
The recent Labor government's $12.9 billion Water for the Future program aimed to manage salinity by promoting more efficient on-farm water use. while targeted projects under the $2 billion Caring for our Country initiative addressed salinity and the management of native vegetation.
The federal Coalition government’s National Landcare Programme consolidates several previous natural-resource management initiatives and will roll out specific agricultural programs relating to soil monitoring and management, over coming months.
The Basin Plan being prepared by the Murray-Darling Basin Authority will help ensure that salt concentration and load targets are met and water quality is adequate by flushing out salt with water flows and encouraging agriculturalists to adopt less damaging land-management practices, with benefits flowing to irrigators.
As part of Murray-Darling Basin reforms, the federal government is acquiring water entitlements so as to return more water to the environment, providing increased flows to rivers and wetlands. Such ‘environmental watering’ is helpful on several fronts; it:
- achieves more natural wetting and drying cycles;
- flushes out toxicants;
- improves water quality; and
- minimises the exposure of soil to oxygen.
Shrinking farming’s water footprint
Right now, CSIRO researchers are looking at ways to reduce agricultural enterprises’ water footprints.
Sources of water for farming enterprises typically include natural rainfall over agricultural lands and water taken from rivers, lakes and groundwater resources (often transported to farms via irrigation channels). Water storage facilities that capture rain, such as on-farm tanks and dams, can also affect a farm’s water footprint.
A farm’s water-usage impact must be considered in the context of local water scarcity (expressed as H2Oe, where 'e' stands for 'equivalent', a unit similar to the CO2e used in carbon footprinting that allows comparison among products and production systems from different regions and climates).
Other water-saving innovations
CSIRO researchers are also investigating the potential of introducing beneficial bacteria and new farming practices to reduce water repellency in sandy soils; and using satellite mapping to estimate the extent of salinity in a region.
As part of its Adaptive Water Management Project, Tasmania’s SENSE-T is employing advanced sensor technology to help dairy farmers and crop growers monitor their water needs more accurately, predict water flows and share water accordingly.
United Nations: System of Environmental-Economic Accounts – Water (SEEA-W)
Regional Institute Australia report on water scarcity and global food security, 2013
Australian Government Department of Environment water policy
Department of Environment on soil degradation and erosion, acidification, clearing of vegetation and loss of soil carbon
ABS: Water Use on Australian Farms (cat 4618.0) (2012-2013)
ABS: Water in Australia ABS (2007)
Australian Government’s Sustainable Rural Water Use and Infrastructure Program (SRWUIP)
South Australian River Murray Sustainability Irrigation Industry Improvement Program
Murray-Darling Basin Authority (MDBA)
MDBA Basin Plan
CSIRO: Measuring farms’ water footprints
CSIRO: Reducing water repellency in sandy soils
CSIRO: Satellite mapping to estimate salinity
SENSE-T’s Adaptive Water Management Project