AUSTRALIA

INTRODUCTION

Irrigation is a widespread practice required in many areas of Australia, the driest inhabited continent, to supplement low rainfall with water from other sources to assist in growing crops and pasture.

The irrigated production of food and natural fiber is a great stimulus to regional economies:

* Irrigated farms tend to have relatively high levels of

labor per hectare

* Engineering and technical support

is needed for irrigation delivery and drainage systems

* Local processing, packaging and transport generate more jobs and maintain communities

* Local produce (fruit, nuts, wine and cheese) complements tourism and dining experiences.

* There are 40,000 irrigators in Australia

* They farm 5% of tilled agricultural lands (less than 1% of Australia)

* Irrigation accounts for 60-70% of water withdrawn for human consumption

* Irrigators produce 30% of all agricultural value and half the profit within agriculture

* Irrigated production is valued at $9-11.5 billion/yr.

• Irrigation is a driver of regional economies

Irrigation on Australian Farms

Australian agricultural production helps provide food and clothing for a nation of over 20 million people. In addition, Australia exports around 65% of its agricultural production to international markets.

Irrigated land area - 1983-84 to 2004-05

Large-scale irrigation began in Australia in the late 1880s. The area irrigated grew steadily from the 1920s until the mid 1950s, then increased dramatically until the mid-1990s. Since

then it has fluctuated between 2.0 and 2.5 million ha, influenced by seasonal water availability. In 1995, a ‘Cap’ was

introduced for diversions in the Murray Darling Basin.

Who Irrigates and Why?

Farmers across all states of Australia use irrigation water to supplement rainfall in agricultural production systems; with methods used impacted by differing water availability, soil type, topography, state legislation, water charges etc. In 2004-05, New South Wales farmers used 4,133 gigalitres (GL) of water which was 34% of all water used by agriculture, including water for stock. Victoria followed with 27% and Queensland 24%.

Water Origins

Most water used for irrigation originates from Australia's major river systems, the Murray-Darling system in eastern Australia and the Ord River in the Kimberley region of Western Australia. Other significant river/dam systems can be found on the Burdekin River in Queensland, in the south-west of Western Australia and in the MacAlister district of Victoria. Another large source of water in Australia is the ground water available from the Great Artesian Basin, which provides for livestock and crops over much of north-eastern Australia via natural springs and man-made bores

Water consumption in Australia

Surface water, drawn from rivers, lakes, weirs and dams, is the main source of irrigation water across all industries. The relative importance of other water sources - groundwater (in underground streams and aquifers), town or country reticulated mains supply, and on-farm and off-farm recycled or reused water (used, captured, treated and reused) - varies considerably between irrigated activities and location. With South Australia and the Northern Territory the exceptions, all other states rely mainly on surface water. 

http://www.abs.gov.au/ausstats/abs@.nsf/mf/4610.0.55.002

Murray-Darling BasinSurface irrigation was the most common method of irrigation in the Murray-Darling Basin in 2008-09, utilized by 5,296 agricultural businesses. These businesses accounted for 69% of all agricultural businesses in Australia using surface irrigation. Above-ground drip or trickle irrigation was the next most common method (3,688), followed by microspray sprinklers (1,891).

Murray Darling Basin

Ord River

The Ord River is a 320 kilometer long river in the Kimberley region of Western Australia. The river's catchment covers 46,100 square kilometers. The Ord River Irrigation Scheme was built in stages during the 20th century.

Ord River Sandalwood Plantation

Ord Stage 1 - 14,000 ha of irrigated farm land

The Ord River Irrigation Area includes approximately 14,000 hectares of developed land, which has access to considerable water resources from Lake Argyle on the Ord River. This land is harvested to produce a diverse range of crops including: chickpeas, sorghum seed, melons, pumpkins, mangoes, bananas, citrus, irrigated pasture, tropical forests and sugar cane. Sugar production accounts for approximately on third, by area, of the cultivated land in the ORIA.

Burdekin River

The Burdekin River in Queensland, Australia rises on the western slope of the Seaview Range and flows into the Pacific Ocean at Upstart Bay over 200 km to the southeast of the source.

Great Artesian Basin

The Great Artesian Basin is one of the largest underground fresh-water reservoirs in the world.  It underlies approximately 22% of Australia – occupying an area of over 1.7 million square kilometers beneath the arid and semi-arid parts of Queensland, New South Wales, South Australia and the Northern Territory.  The GAB is Australia’s most important water resource, and for more than a century it has sustained much of the pastoral and community needs of a fifth of Australia’s landmass.

Blowering Dam Blowering Dam is a major ungated rock fill with clay core embankment dam with concrete chute spillway across the Tumut River upstream of Tumut in the Snowy Mountains region of New South Wales, Australia. The dam's purpose includes flood mitigation, hydropower, irrigation, water supply and conservation. The dam is part of the Snowy Mountains Scheme, a vast hydroelectricity and irrigation complex constructed in south-east Australia between 1949 and 1974 and now run by Snowy Hydro. The impounded reservoir is called Blowering Reservoir.

METHODS AND TECHNIQUES OF IRRIGATION

As water becomes less accessible, Australians will need to look at more efficient ways to irrigate. The current worldwide trend

towards the use of recycled water in major urban applications

shows great promise and is increasing as the cost of potable water climbs and treated water becomes more accessible. Large open spaces, like sports fields and ovals, lend themselves to using recycled water. Farmers use a variety of irrigation techniques to apply water to their crops and pastures.

Drip or Trickle Irrigation Method

Drip irrigation was the most common method of irrigation in Australia.

Drip irrigation was used on 80% of farms where their main irrigation activity was fruit growing and 73% of farms whose main irrigation activity was grape growing.

Environmental Sustainability* Water saving (i.e. greater efficiency and reduced losses)* Reduced drainage hazards* Ability to utilize lower quality water* Reduced farm inputs* Increased land utilization (i.e. irregular topography)* Less off-site impact of nutrients

Crop & Farm Benefits• Cost savings (i.e. energy, water, fertilizer)• Increased distribution uniformity• Precision water application• Increased production per ML• Improved plant health (i.e. salinity, fungal, nutrient

management)• Increased access/traffic ability• Greater weed control• SDI Distribution Uniformity (DU) can be• 93% or higher, compared with sprinklers at 60% to 80% and

surface irrigation at 50% to 60%

There are two types of drip irrigation:1. Surface drip irrigation: Water is applied directly to the soil surface.2. Sub-surface drip irrigation: Water is below the soil surface.

Sub-surface IrrigationSurface Irrigation

Some advantages of a sub-surface drip system are:

* Reduced water consumption (perhaps as high as 50%

depending on prior watering practices). There is no evaporation, wind-deflection, run-off or overspray.

* No vandalism or system damage as there are no surface components;

* Hazard-free for grounds-users;* Ideal for treated effluent/wastewater. It is totally

accepted by EPA/Health Commission;* Irrigation scheduling can occur even when the

grounds are in use.

Furrow systems

This system comprises a series of small, shallow channels used to guide

water down a slope across a paddock.

Furrows are generally straight but may also be

curved to follow the contour of the land,

especially on steeply sloping land. Row crops

are typically grown on the ridge or bed between the furrows, spaced from 1 m

apart.

Flood or border check systemsThese systems divide the

paddock into bays separated by parallel

ridges/border checks. Water flows down the paddock's slope as a sheet guided by ridges. On steeply sloping

lands, ridges are more closely spaced and may be curved to follow the contour of the land. Border systems are suited to orchards and vineyards, and for pastures

and grain crops.

Level basin systemsThese systems differ from traditional Border check or flood systems in that the slope of the land is level and the area's ends are closed. Water is applied at high volumes to achieve an even, rapid ponding of the desired application depth within basins.

SPRINKLER METHODS

• Centre-pivot sprinkler systemsCentre-pivot sprinkler is a self-propelled system in which a single pipeline supported by a row of mobile towers is suspended 2–4 m above ground.

Hand move sprinkler systems

• Hand move sprinkler systems are a series of lightweight pipeline sections that are moved manually for successive irrigations. Lateral pipelines are connected to a mainline, which may be portable or buried. Hand move systems are often used for small, irregular areas. Hand move systems are not suited to tall-growing field crops due to difficulty in repositioning laterals. Labor requirements are higher than for all other sprinklers.

Solid set/fixed sprinkler systems

• Solid set/fixed refer to a stationary sprinkler system. Water-supply pipelines are generally fixed (usually below the soil surface) and sprinkler nozzles are elevated above the surface. Solid-set systems are commonly used in orchards and vineyards for frost protection and crop cooling. Solid-set systems are also widely used on turf and in landscaping.

Travelling gun sprinkler systems

• Travelling gun systems use a large sprinkler mounted on a wheel or trailer, fed by a flexible rubber hose. The sprinkler is self-propelled while applying water, travelling in a lane guided by a cable. The system requires high operating pressures, with 100 psi not uncommon.

Side-roll wheel-move systems

• Side-roll wheel-move systems have large-diameter wheels mounted on a pipeline, enabling the line to be rolled as a unit to successive positions across the field. Crop type is an important consideration for this system because the pipeline is roughly 1 m above ground.

Linear or lateral-move systems

• Linear or lateral-move systems are similar to Centre-pivot systems, except that the lateral line and towers move in a continuous straight path across a rectangular field. Water may be supplied by a flexible hose or pressurized from a concrete-lined ditch along the field's edge.