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24.1 WATER SUPPLY AND USE IN THE AUSTRALIAN ECONOMY - 2000-01
Source: Water Account, Australia, 2000-01 (4610.0).
Water consumption by industry
Agriculture was by far the largest consumer of water in 2000-01, accounting for 67% (16,660 GL) of total water use in Australia (graph 24.2, table 24.3). Households were the next highest consumers of water, accounting for 8.8% (2,181 GL) of water use. Total water use in households increased 19% between 1996-97 and 2000-01. The average household water use was 115 kilolitres/person in 2000-01. The water supply, sewerage and drainage services industry was also a significant consumer of water, accounting for 7.2% (1,794 GL) of water use, followed by the electricity and gas supply industry which consumed 6.8% (1,688 GL), excluding in-stream water use for hydro-electricity generation. Mining accounted for 1.6% (401 GL) of water use, while manufacturing accounted for 3.5% (866 GL) of the total water consumption in 2000-01.
New South Wales and the Australian Capital Territory combined used the most water - 9,425 GL (or 38% of the total) - and 78% of this was used in agriculture. In Victoria, agriculture accounted for 52% of the total, however, the electricity and gas supply industry also contributed a high proportion (22%) compared with that contributed by other states and territories.
Water use by agriculture
Water used by agriculture includes water applied through irrigation to crops, pastures, or fed to livestock, that has been directly extracted from the environment by farmers (e.g. from bores, on-farm dams, rivers) or supplied by water providers (e.g. irrigation authorities). It excludes the use of rainwater.
While 2000-01 is the latest year for which information on water use is available for the entire economy, information on agricultural water use is available for 2002-03. The estimates of water use by agriculture for 2000-01 and 2002-03 are not strictly comparable, but a lower level of water use by the sector is apparent and may be attributed to the drought.
Australian agricultural establishments applied 10,404 GL of irrigation water to 2.4 million hectares (ha) of crops and pastures in 2002-03 (table 24.4). Agricultural establishments in New South Wales applied the largest volume of irrigation water (4,273 GL) to the largest area (939,000 ha) of the states and territories. Western Australian agricultural establishments reported the highest irrigation application rate (6.5 megalitres (ML)/ha) and Tasmanian establishments reported the lowest (2.4 ML/ha).
In Australia during 2002-03, 10,404 GL of irrigation water was used on agricultural establishments (table 24.5). The largest volume of irrigation water that was applied on pastures for grazing purposes (2,827 GL), followed by cotton (1,526 GL), sugar cane (1,293 GL) and cereal crops for grains or seed (1,002 GL). The smallest volume of irrigation water was used for vegetables for seed (8 GL) followed by nurseries, cut flowers or cultivated turf (78 GL). Rice required the highest application rate of irrigation water (14.1 ML/ha), followed by cotton (6.5 ML/ha). Vegetables for seed have the lowest application rate (2.3 ML/ha).
Household water use
Water use by households (also referred to as domestic water use) includes water that is used for human consumption (such as for drinking and cooking) as well as water used by households for cleaning or outdoors (such as water for gardens and swimming pools).
In 2000-01 the total water used by households was 2,181 GL, increasing from 1,829 GL in 1996-97 and 1,704 GL in 1993-94. This rise can be attributed in part to an increase of population (6% nationally from 1993-94 to 2000-01) and improved metering, coverage and reporting of water use in 2000-01. The majority of household water was used for outdoor purposes (44%), followed by indoor uses, including bathrooms (20%) and toilets (15%) (graph 24.6).
Reuse water is defined as wastewater that may have been treated to some extent and then used again without first being discharged to the environment. Reuse water is supplied mainly by the water supply industry, but may also be supplied by other industries (such as mining and manufacturing). Reuse water supplied by irrigation/rural water providers through regional reuse schemes has also been included.
The use of reuse water has increased almost threefold since 1996-97, although the volume is still relatively small. In 1996-97 there were 134 GL of reuse water used in Australia, which made up less than 1% of total water use in that year. By 2000-01 this volume had increased to 516 GL. However, this use still accounted for less than 1% of total water use. A large proportion of reuse water use is sourced from rural/irrigation regional reuse schemes.
The agriculture industry was the largest user of reuse water in 2000-01, accounting for 423 GL or 82% of all reuse water used in Australia (graph 24.7). The majority of reuse water used by the agriculture industry was for application to pastures (45%), although rice crops were also significant users (29%).
Rainfall, or the lack of it, is the single most important factor determining land use and rural production in Australia. The relative scarcity of both surface water and groundwater resources, together with low rates of precipitation, has led to programs to regulate water supply by construction of dams, reservoirs, large tanks and other storages.
Surface water stocks
Water stocks are usually divided into surface water and groundwater resources. Surface water resources are often represented by Mean Annual Run-off (MAR). MAR is the average annual streamflow passing a specified point (NLWRA 2001) or the maximum average annual flow observed in a river basin (AWRC 1987). In 2000, the total MAR for Australia was 387,184 GL, but the distribution was geographically uneven (map 24.8).
24.8 SURFACE WATER, MEAN ANNUAL RUN-OFF, By river basin - 2000
(a) Data not available for a number of reasons. Refer to <http://audit.ea.gov.au//> for more information.
Source: Adapted from AWRC; NLWRA 2001.
Table 24.9 summarises Australia's surface water stocks by drainage division. The drainage division with the highest intensity (GL/km2) of run-off is Tasmania with 0.67 GL/km2. Conversely, the vast area of the Western Plateau, almost a third of Australia's total land area, has no significant run-off.
Developed yield (also referred to as Economic Allocated volumes) is the average annual volume of water that can be diverted for use with the existing infrastructure (NLWRA 2001). Map 24.10 shows the developed yield as a percentage of MAR in 2000. The highest proportions are located in the south east and north east areas of Australia.
24.10 SURFACE WATER, DEVELOPED YIELD, By river basin - 2000
Source: Adapted from AWRC; NLWRA 2001.
The volume of groundwater that exists in Australia is not known with certainty. The volume changes as water percolates through the ground to aquifers (underground water resources) and through water being extracted (e.g. from bores). Instead of an absolute measure of groundwater stock, a proxy is used. This is the amount of water that can be sustainably extracted, referred to as sustainable yield.
Sustainable yield is defined as:
The 2001 National Land and Water Resources Audit (NLWRA) estimated the sustainable yield of groundwater in Australia to be 29,173 GL. Groundwater is not all of equal quality. In particular, the concentration of salt dissolved in water varies (map 24.11). The level of dissolved salt determines the potential uses of the water. The higher the salt level the less suitable the water is for human consumption or agriculture. Typically, a salinity level of more than 1,500 milligrams/litre (mg/L) restricts the use of water for irrigation. Map 24.11 shows the percentage of groundwater resource in each province with salinity over 1,500 (mg/L) in 2000. Salt occurs naturally in Australian soils but through irrigation and land clearing the levels of salt can increase in soils and water. Table 24.12 shows, proportionally, Northern Territory, Tasmania and Queensland have groundwater with the lowest salinity levels (less than 1,500 mg/L), while Victoria, South Australia and Western Australia have the highest (1,500 mg/L and over).
24.11 GROUNDWATER, Salinity levels over 1,500 mg/L - 2000
Source: Data based on NLWRA 2001. Australian Groundwater Provinces are based on data provided in 2000 with the permission of the Queensland Department of Natural Resources and Mines, Environment ACT, NSW Department of Land and Water Conservation, NT Department of Lands, Planning and Environment, SA Department of Water Resources, Tasmanian Department of Primary Industries, Water and Environment, Victorian Department of Natural Resources and the Environment, WA Water and Rivers Commission, and the Australian Surveying and Land Information Group.
There are several dimensions to water assets including the physical availability of water or water stocks, the administrative (e.g. licences and entitlements) and the physical infrastructure (dams, pipes, etc.) that are used to store and deliver water.
Information on the storage capacity of large dams in each state and territory (except the Australian Capital Territory) is available from the Register of Large Dams (Australian National Committee on Large Dams 2002). There are approximately 500 large dams in Australia with a storage capacity of 84,793 GL. Tasmania (24,340 GL) and New South Wales (24,814 GL) have the largest storage capacity, while the Australian Capital Territory (124 GL) and South Australia (261 GL) have the least (graph 24.13). Most of Australia's dam capacity has been built since 1970 (graph 24.14).
The majority of Australians (80%) rely on mains or town water for drinking (graph 24.15). This reliance on mains or town water for drinking is more pronounced in the capital cities (89% of households in 2004) than outside capital cities (67% of households). South Australians are least reliant on mains as their main source of water for drinking although this has increased significantly from 50% in 2001 to 60% in 2004.
The use of water filters in drinking water in Australian households has also increased from 21% in 2001 to 26% of households in 2004 (graph 24.16). This increase in the use of water filters was greatest in South Australia (from 23% in 2001 to 30% in 2004), and Western Australia (from 24% in 2001 to 29% in 2004).
There was a general increase in the satisfaction with the quality of mains/town water for drinking, with 70% of people satisfied in 2004 compared with 66% in 2001 (graph 24.17). The level of satisfaction varied between states and territories. The Northern Territory (89%) and the Australian Capital Territory (87%) had the highest rates of satisfaction, while South Australia (52%) had the lowest levels of satisfaction.
New South Wales, Victoria, Queensland, South Australia and Tasmania all reported increased satisfaction with the quality of their mains drinking water since 2001. Generally, there has been an increase in the levels of satisfaction across Australia (from 64% in 1994 to 70% in 2004).
Water conservation practices
During the three years to mid-2004, the majority of Australia experienced drought conditions. This led to the introduction of water restrictions in most capital cities around Australia during 2002-03. Water restrictions varied from voluntary reductions of water use to mandatory restrictions. Sydney, Melbourne, Perth, Hobart and Canberra all experienced water restrictions during 2002-03. Brisbane had permanent restrictions on the times residents were able to use sprinklers. The only capital city not affected by water restrictions during 2002-03 was Darwin.
For households, these restrictions limited the use of water outside the house, primarily in the garden. The following data reflect the impact of the drought and subsequent water restrictions in many regions of Australia in recent times. For example, 32% of households in 2004 nominated supply restrictions as a problem compared with 7% in 2001.
The use of both reduced flow shower heads and dual flush toilets in Australian households continues to grow. Nearly three-quarters of households (74%) had dual flush toilets in 2004, up from 64% in 2001 (graph 24.18). Reduced flow shower heads were installed in 44% of households (up from 35% in 2001). Nearly one in five (18%) Australian households have neither a dual flush toilet nor a reduced flow shower head, down from 27% in 2001.
Less than half of all Australian households (46%) reported using one or more water conservation practices in 2004.
The most popular measures adopted included using full loads when washing dishes and clothes, and taking shorter showers (18% of all households reported doing each of these) (graph 24.19). These measures were particularly popular in Victoria, where over one-quarter of households undertook these activities.
Recycling and/or reusing water was reported by 16% of all households, up from 11% in 2001. Of Australian Capital Territory households 28% recycled or reused water (up from 10% in 2001). These were also popular activities in Victoria and Western Australia (21%, up from 14% in both states). Turning off or repairing dripping taps to conserve water was also reported by 16% of households (down from 20% in 2001).
Since 1994, the proportion of Australian households with gardens has steadily declined (from 87% in 1994 to 83% in 2004). More than 90% of households with gardens reported taking measures in the garden to conserve water. States and territories that reported an overall increase in measures to conserve water in the garden since 2001 included New South Wales (86% to 90% of households), Victoria (90% to 93%) and South Australia (90% to 93%).
The measure reported most often by households to conserve water in the garden was using mulch (58% in 2004, up from 51% in 2001) (graph 24.20). Watering early in the morning or late in the evening was the next most popular water conservation measure for the garden, (23%). Almost one in five households (18%) used recycled water on the garden, a significant increase from 11% in 2001.
In 2004, 17% of households reported planting native trees or shrubs as a water conservation measure, up from 10% in 2001. Over one-quarter of households in South Australia and Western Australia reported this (26% and 28%, respectively).
Hand watering of the garden was used more often in 2004 than in previous years (graph 24.21). In 2004, 71% of Australian households hand watered their garden compared with 66% in 2001. There was a corresponding decrease in the use of fixed and movable sprinklers (from 28% in 2001 to 15% in 2004 for movable sprinklers, and from 31% to 22% for fixed sprinkler systems). Just over three quarters of households in New South Wales, Victoria and the Australian Capital Territory used hand watering.