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1301.0 - Year Book Australia, 2008  
Previous ISSUE Released at 11:30 AM (CANBERRA TIME) 07/02/2008   
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WATER

Water is critical for sustaining life. It performs essential functions within terrestrial and marine ecosystems and represents an important input into Australia's economy. To assess the role of water within Australia's society and the environment, the National Water Commission undertook an assessment of the status of Australia's water resources in 2005. The assessment focused on three major themes: water availability, water use, and river and wetland health. The key results are described in the following sections.


Water availability

Water availability is important because it dictates the quantity of water which society can use to grow food and for recreation, industrial and domestic purposes. Water availability also influences multiple ecological processes.

The major source of water availability in Australia is rainfall. This affects water run-off and groundwater recharge. The quantity of water stored above ground (e.g. in dams) and below ground (e.g. in aquifers) is determined by the volumes of run-off and recharge. Water storage in dams and aquifers secures water supplies for society. This is important in Australia because it has extreme variability in rainfall both across the continent and from year-to-year. These components of water availability are discussed in the following sections.

Rainfall

Average annual rainfall in Australia varies substantially across the continent. Large areas of Australia have an average annual rainfall of 600-1,500 millimetres (mm), an amount comparable to most of Europe and North America. However, half the continent has an average annual rainfall below 300 mm.

Another key feature of Australia's rainfall is not the amount but the variability from year-to-year and season-to-season. Many parts of Australia experienced below average rainfall in 2004-05, with drought conditions existing in some areas.

In 2004-05 it was estimated that 2,789,424 gigalitres (GL) of rain fell across Australia. The majority fell in Queensland (865,973 GL), followed by Western Australia (639,609 GL) and the Northern Territory (505,623 GL). The uneven distribution of rain is highlighted in map 3.1, with high concentrations along the eastern seaboard, northern Australia and the west coast of Tasmania.


3.1 Rainfall concentration - 2004-05
Diagram: 3.1 Rainfall concentration—2004–05


The drought conditions experienced across much of Australia in 2004-05 are evident by analysing the deviation of 2004-05 rainfall from the long-term (30 year) average annual rainfall, as illustrated in map 3.2. A significant proportion of central Western Australia and central Australia received less than half of their average annual rainfall for 2004-05. Above average rainfall was experienced in relatively few areas.
3.2 Rainfall anomaly - 2004-05
Diagram: 3.2 Rainfall anomaly—2004–05


Run-off

In most parts of Australia, only a small proportion of rainfall becomes run-off into rivers, lakes, dams and aquifers. This is due to the high rate of evapotranspiration and variability in the amount of rainfall. It is also a result of generally flat topography across most of the continent. Run-off is high in northern Australia and parts of Tasmania where annual rainfall is relatively high. Run-off in 2004-05 was estimated to be 242,799 GL (9% of the estimated rainfall for 2004-05). The highest amounts occurred in the following drainage divisions:
  • Gulf of Carpentaria (62,060 GL)
  • Timor Sea (50,240 GL)
  • North East Coast (40,210 GL).

Most of Australia received below average annual run-off for 2004-05 (map 3.3). The northern coastline and most of the eastern half of the continent only received 50-75% of average annual run-off in 2004-05, while a large proportion of Western Australia received below 25% of average annual run-off. The only region of Australia that received above average annual run-off in 2004-05 was the south-western corner of Western Australia (110%).
3.3 Runoff anomaly, By drainage division - 2004-05
Diagram: 3.3 Runoff anomaly, By drainage division—2004–05


Groundwater recharge

Groundwater recharge is the inflow of water to the groundwater system from the Earth's surface. Infiltration of rainfall and its movement to the watertable is one form of natural recharge.

The amount of groundwater recharge for 2004-05 shows a similar geographical pattern to that of run-off across the country. Where it differs is due to the influence of soil texture and other biophysical characteristics.

Average annual deep drainage was found to be highest in Tasmania, the south-eastern corner of Australia, the northern tip of Western Australia and the area around Darwin in the Northern Territory. Most of Australia had below average annual deep drainage.Water storage

Surface water and groundwater are stored in a number of ways to supply agriculture, industry and urban users. Some of these storages include: large dams, farm dams and aquifers (underground storage).

There are 501 large dams in Australia (map 3.4). A large dam is defined as a dam with a crest height of greater than 15 metres, or greater than 10 metres but meeting other size criteria.

3.4 Location of large dams(a), By drainage division - June 2005
Diagram: 3.4 Location of large dams(a), By drainage division—June 2005

The total storage capacity of Australia's large dams as at June 2005 was 83,853 GL. Storage levels declined continuously in the period 2001-05 (graph 3.5) as a result of reduced inflows, continued water extractions and climatic conditions. In the 12 months to June 2005 total storage levels decreased by 10% (from 44,164 GL to 39,959 GL). At June 2005, the dams with the highest storage levels were located in Western Australia (83% of total capacity) and the Northern Territory (70%). The states where dams with the lowest levels were located in New South Wales (33%) and Victoria (39%).

3.5 Total storage level of large dams
Graph: 3.5 Total storage level of large dams

The progressive decline in the water storage level of large dams across much of Australia during the period from July 2001 to June 2005 is shown in maps 3.6 and 3.7. The decrease in storage level (expressed as a percentage of total storage capacity) is apparent in the majority of drainage divisions, particularly those with significant population and industry; for example, the Murray-Darling, South-East Coast, North-East Coast and South-West Coast drainage divisions.
3.6 Storage level of large dams, By drainage division - July
Diagram: 3.6 Storage level of large dams, By drainage division—July


3.7 Large dams storage levels, By drainage division - June 2005
Diagram: 3.7 Large dams storage levels, By drainage division—June 2005


Water use

Water use is important to quantify because it gives society a baseline for the amount of water that it needs to operate. Measuring patterns of water use is important when predicting future land use, developing policy initiatives, or when reviewing the impact of present and past practices. For example, they give an indication of where water use efficiency programs or the buy-back of water licences should be focused. An assessment of water use by industry and households enables water managers to target management tools like drought contingency programmes (e.g. water restrictions). Comparing water use with the economic value generated shows which activities are returning more economic value to society, as a result of using the resource.

Water use in the economy

The total amount of water extracted from the environment in 2004-05 was 79,784 GL (24% of Australia's total water resource). Of this 60,436 GL was used in-stream (mostly by hydro-electricity generators) and 1,000 GL of environmental provisions were returned to the environment (mostly by the Water supply industry) and, therefore, not consumed. The remaining 18,342 GL comprises self-extracted and distributed water consumption, which when added to the 425 GL of water reuse resulted in total water consumption in 2004-05 of 18,767 GL. Almost two-thirds of this total was used by producers in the Agriculture industry (65%) and 11% by operators in the Water supply industry (which includes sewerage and drainage services); households share of total water consumption was also 11% (graph 3.8).

3.8 Water consumption
Graph: 3.8 Water consumption
The three main water consuming sectors in each state and the Northern Territory in 2004-05 are shown in table 3.9. Agricultural producers were the major water consumers in all states and in the Northern Territory. In New South Wales (including the Australian Capital Territory) the main water using agriculture industries involved cotton and grain producers; in Queensland, cotton and sugar producers; and in South Australia, pasturalists and grape growers.

3.9 WATER CONSUMPTION, By major sector - 2004-05

Consumption
Proportion of total
State/territory
GL
%

New South Wales(a)
Agriculture
4 134
69
Water supply
637
11
Households
604
10
Victoria
Agriculture
3 281
66
Water supply
793
16
Households
405
8
Queensland
Agriculture
2 916
67
Households
493
11
Water supply
426
10
South Australia
Agriculture
1 020
75
Households
144
11
Manufacturing
55
4
Western Australia
Agriculture
535
36
Households
362
24
Mining
183
12
Tasmania
Agriculture
258
59
Households
69
16
Manufacturing
49
11
Northern Territory
Agriculture
47
33
Households
31
22
Other industries
30
21

(a) Includes Australian Capital Territory.
Source: Experimental Estimates of Regional Water Use, Australlia (4610.0.55.002).


Household water use

Water consumption by households in 2004-05 was 2,108 GL. This compares with 2,278 GL in 2000-01. Overall, there was an 8% decrease in household water consumption between 2000-01 and 2004-05.

The majority of water used in 2004-05 was sourced from distributed water provided by water suppliers (89%); the remainder was from a self-extracted source (including groundwater bores and rainwater tanks). Rates of household water consumption in states and territories for each of the years 2000-01 and 2004-05 are shown in graph 3.10. When compared with rates in 2000-01, household water use per person in 2004-05 fell in all states and territories, except in Tasmania.

3.10 Household water consumption per person
Graph: 3.10 Household water consumption per person

Agricultural water use

The Agriculture industry in Australia is the major consumer of water, accounting for 65% of total water consumption in 2004-05.

Of the water used for agricultural production in 2004-05, 91% was used for irrigation of crops and pastures. The remainder was used for other agricultural purposes, such as stock drinking water, dairy and piggery cleaning.

Water consumption in the Agriculture industry fell by 23% between 2000-01 and 2004-05; water consumption for rice irrigation fell by 72% and for cotton by 37% (graph 3.11). The large decrease in the use of water in irrigating rice and cotton crops in 2004-05 can be attributed to the reduced sowings as a result of the dry conditions and, consequently, reduced water availability.
3.11 Water consumption in agriculture, by activity
Graph: 3.11 Water consumption in agriculture, by activity

Map 3.12 shows irrigated areas used for crops and pastures as a percentage of total crop and pasture land, by drainage division. The majority of intensive crop and pasture irrigation occurs in the Murray-Darling drainage division. The article Irrigation on Australian farms in the Agriculture chapter provides more information on water use.

3.12 Irrigated areas, By drainage division - 2004-05
Diagram: 3.12 Irrigated areas, By drainage division—2004–05

Water use and sources of water

Water availability compared with water use in Australia in 2004-05 is shown in table 3.13.

3.13 WATER RESOURCE AND WATER USE - 2004-05

NSW
Vic.
Qld
SA
WA
Tas.
NT
ACT
Aust.

Total Water Resource GL
45 369
21 332
112 905
4 321
49 094
47 056
55 784
256
336 117
Water Use
Self-extracted(a) GL
16 528
11 213
7 964
1 352
3 417
39 081
145
84
79 784
Distributed GL
3 112
4 004
2 652
461
736
229
66
77
11 337
Reuse GL
194
131
52
22
18
5
2
2
425
In-stream GL
10 703
5 977
3 271
8
1 939
38 532
4
-
60 436
Total water consumption(b) GL
5 922
4 993
4 361
1 365
1 495
434
141
56
18 767
Total water resource consumed by the economy %
13
23
4
32
3
1
-
22
6

- nil or rounded to zero (including null cells)
(a) Includes water extracted directly from the environment for use by the economy, and includes water used consumptively and water returned to the environment after non-consumptive use.
(b) Water consumption = self extracted + distributed + reuse - distributed water supplied to other users - in-stream - distributed water used by the environment.
Source: Water Account, Australia (4610.0).


Almost half of Australia's self-extracted and in-stream water use occurred in Tasmania - nearly 98% of Tasmania's self-extracted water was used in-stream for hydro-electricity. Victoria was the highest user of distributed water and New South Wales used the majority of reuse water. South Australia consumed the largest proportion of its total resource (32%), while the Northern Territory (1%) and Tasmania (less than 1%) consumed the lowest proportions, due to their relatively high rainfall and low populations.

The majority of the 11,160 GL of water distributed by water suppliers (10,712 GL or 96%) was sourced from inland surface water (table 3.14). Groundwater accounted for 448 GL (4%), of which just over half was in Western Australia (229 GL). Desalinated sea water accounted for the remainder (0.2 GL).


3.14 ORIGIN OF DISTRIBUTED WATER(a)

NSW
Vic.
Qld
SA
WA
Tas.
NT
ACT
Aust.
GL
GL
GL
GL
GL
GL
GL
GL
GL

Surface water
3 013
3 995
2 532
444
497
112
42
77
10 712
Groundwater
61
9
109
17
229
(b) -
21
-
448
Desalinated water(c)
-
-
(b) -
(b) -
(b) -
-
-
-
(b) -
Total
3 074
4 004
2 642
461
726
112
64
77
11 160

- nil or rounded to zero (including null cells)
(a) Less than 1%.
(b) Water supply, sewerage and drainage industry only, excludes water provided by other industries.
(c) Includes sea water only.
Source: Water Account, Australia (4610.0).


The three highest water using regions in 2004-05 were the Murrumbidgee Water Management Area (WMA) (New South Wales), the Broken, Goulburn and Campaspe WMA and the Murray River WMA (both in Victoria) (map 3.15). In 2004-05 the top 20 WMAs accounted for 70% of total water consumption; the top 30 WMAs consumed 81%.

3.15 Water consumption, By water management area - 2004-05
Diagram: 3.15 Water consumption, By water management area—2004–05

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