Australian Natural Resources Atlas

Natural Resource Topics

Irrigation - Infrastructure

Australia

What off-farm infrastructure is used to support irrigation?

What irrigation methods are used in Australia?

A range of irrigation methods are used in Australia including:

All things being equal, flood and furrow irrigation tend to be less efficient in terms of water use methods. Despite this, both flood and furrow irrigation are commonly used, with flood irrigation used for rice and pasture production and furrow irrigation being the predominant method for grapes, trees, horticultural and field crops, particularly in the irrigation systems comprising older infrastructure.

There is limited information available on the type of irrigation systems installed on various farms and the resulting environmental and/or production benefits. Available and anecdotal data indicate an increase in the adoption of more efficient water application methods, with the installation of this infrastructure occurring in all Greenfield irrigation districts. The move to more efficient irrigation practices reflects the increasing recognition that water resources are becoming scarcer, with demand for water increasing, and their adoption is a desired outcome for profitability and the environment. More information is required on the extent of adoption of these systems to and observed benefits. It is possible to collect this information as part of the next Australian Bureau of Statistics Agricultural Census.

The Murray-Darling Basin: a case study

The total area of irrigated crops and pastures in the Murray-Darling Basin represents approximately 64% of Australia's total area of irrigated crops and pastures. The main irrigated enterprises in the Basin include rice, cotton, dairy, horticulture and viticulture. Water used for irrigation represents 75% of the total volume of water used for irrigation in Australia.

The Murray-Darling Basin Commission is developing an Irrigation Management and Reporting System that will provide access to irrigation data characterising the extent, location, value and efficiency of irrigation activities in the Basin. Data and information that is currently available on irrigation in the Basin has been compiled and presented on the Murray-Darling Basin web page.

Further information

Link to Map maker to make a map using this information.

Irrigation reticulation systems consist of a variety of carriers including, constructed open channels (lined and unlined), natural streams and pipelines (gravity and pressurised). Of the 47 water supply systems reported in the ANCID Benchmarking Report for 1999/2000, a total of 3,370 km of natural stream, 16,250 km of channels or canals and 2,740 km of pipes are used to supply water to irrigation customers. A further 11,850 km of carriers provides water for stock and domestic water consumers. The 47 water supply systems include the majority of water supply systems in Australia, with only a small percentage not reported in the ANCID data.

Most of the water supply systems with a majority of natural carriers are in Queensland. Queensland also has the most length of irrigation pipelines, representing 39% of the 2,740 km of pipeline. Victoria and New South Wales have the majority of channel carriers, representing 45% and 43% respectively. Victoria also has the longest length of Stock and Domestic supply carriers (8,700 km); most of which form part of the Wimmera Mallee Stock and Domestic supply system, the largest system of its kind in Australia. Wimmera-Mallee Water delivers stock and domestic water over the cooler winter months to reduce losses due to evaporation and seepage.

Surface drainage systems cover a total of 840,000 ha and are being serviced by 9,150 km of collector drains. 8,000 km of these drains are constructed open earthen or concrete drainage channels.

The Lower Murray Swamps, South West Irrigation, Coleambally and Ord Irrigation are the only systems that are 100% serviced with surface drainage. The Sunraysia System has the most land serviced by sub-service drainage with 88% of the irrigated area serviced.

28% of the total area contained within the water supply systems in the Murray-Darling Basin (ANCID, 1999/2000) is serviced by surface drainage and 5% is serviced by sub-service drainage.

The average depths to watertable reported for each of the irrigation systems in the ANCID Benchmarking Report 1999/2000 vary from 1.2 m to 35 m. Rising water table levels caused by irrigation is managed by the installation of sub-surface drainage and de-watering bores that serve to protect areas from waterlogging and salinisation. A total of 157,000 ha of irrigated land is serviced by sub-surface drainage, with most of this land being serviced by tile horizontal slotted) drains.

Remaining life of assets and replacement costs

Most water supply assets across the country are long life assets and are less than halfway through there asset lives (ANCID, 1999/2000). The average age of assets, which comprise the 47 water supply systems reported to ANCID in 1999/2000, is 33 years. The weighted average life expectancy of the same assets, when new, is 87 years, and the weighted average remaining life of the assets is 54 years.

The total irrigation asset replacement value of all 47 systems reported in the ANCID Benchmarking Report is $5.19 billion dollars. On average, reported asset renewal fund allocations are about 46% of the annual loss in value of assets. This indicates that, without additional capital funding being provided by way of borrowings or capital grants, insufficient funds are being allocated to future asset replacement. (ANCID, 1999/2000).

ANCID 2000

Table: Extent of System Infrastructure and Replacement Value of Assets
State Natural Water Courses as Carriers Length of Supply Channel Length of Supply Pipeline Length of Stock and Domestic Supply System Area Serviced by Surface Drains Area Serviced by Sub-Surface Drains Replacement Value os Assets 1999/2000
AUS 3,369 16,246 2,744 11,828 8,044 1,108 5,187,428
ACT 0 0 0 0 0 0 0
NSW 0 6,931 283 1,069 3,485 198 1,041,245
NT 0 0 0 0 0 0 0
QLD 2,707 1,122 1,059 100 741 0 1,795,358
SA 0 106 409 0 78 200 187,680
TAS 0 177 61 0 0 0 36,332
VIC 644 7,328 829 10,108 3,580 710 1,956,813
WA 18 582 103 551 160 0 170,000

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