Australian Bureau of Statistics

Rate the ABS website
ABS Home > Statistics > By Release Date
ABS @ Facebook ABS @ Twitter ABS RSS ABS Email notification service
1301.0 - Year Book Australia, 2005  
Previous ISSUE Released at 11:30 AM (CANBERRA TIME) 21/01/2005   
   Page tools: Print Print Page RSS Feed RSS Bookmark and Share Search this Product  
Contents >> Environment >> Water stocks

Rainfall, or the lack of it, is the most important single factor determining land use and rural production in Australia. The scarcity of both surface water and groundwater resources, together with low rates of precipitation, has led to programs to regulate 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 1987a). In 2000 the total MAR for Australia was 387,184 GL, but the distribution was geographically uneven (map 24.25).

24.25 SURFACE WATER, MEAN ANNUAL RUN-OFF (MAR), By river basin - 2000
Map 24.25: SURFACE WATER, MEAN ANNUAL RUN-OFF (MAR), By river basin - 2000


(a) Data not available for a number of reasons. Refer to <http://audit.ea.gov.au//> for more information.

Source: AWRC 1987a; AWRC 1987b; NLWRA 2001.


Table 24.26 summarises Australia's surface water stocks by drainage division. The drainage division with the highest intensity of run-off is Tasmania with 11.8% of the total from only 0.9% of the area. Conversely, the vast area of the Western Plateau, almost a third of Australia's total land area, has no significant run-off at all.


24.26 SURFACE WATER STOCKS - 2000
Mean annual run-off
Area

Drainage division
sq km
GL
%

North-East Coast
451,000
73,411
19.0
South-East Coast(a)
274,000
42,390
10.9
Tasmania(b)
68,200
45,582
11.8
Murray-Darling Basin(a)
1,060,000
23,850
6.2
South Australian Gulf(c)
82,300
952
0.2
South-West Coast
315,000
6,785
1.8
Indian Ocean
519,000
4,609
1.2
Timor Sea
547,000
83,320
21.5
Gulf of Carpentaria
641,000
95,615
24.7
Lake Eyre
1,170,000
8,638
2.2
Bulloo-Bancannia
101,000
546
0.1
Western Plateau
2,450,000
1,486
0.4
Total
(d)7,680,000
387,184
100.0

(a) South-East Coast and Murray-Darling Division. The volume diverted represents the sum of available data (NSW has not reported water use for unregulated surface water management areas).
(b) Tasmanian Division. Volume diverted does not include the hydro-electric scheme diversions.
(c) South Australian Gulf Division. Mean annual outflow includes the flow from surface water management areas Willochra Creek and Lake Torrens, which do not flow to the sea, but flow into the terminal lake, Lake Torrens.
(d) Total area differs slightly from that in table 1.1, due to improvements in mapping reflected in that table, but not in this table.

Source: NLWRA 2001.


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 24.27 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.

24.27 SURFACE WATER, DEVELOPED YIELD, By river basin - 2000
Map 24.27: SURFACE WATER, DEVELOPED YIELD, By river basin - 2000


Source: AWRC 1987a; AWRC 1987b; NLWRA 2001.


Groundwater stocks

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:
    Level of extraction measured over a specified planning time frame that should not be exceeded to protect the higher value social, environmental and economic uses associated with the aquifer (NLWRA 2001).
The National Land and Water Resources Audit 2001 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 24.28). 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 24.28 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 24.29 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 groundwater with the highest salinity levels (1,500 mg/L and over).

24.28 GROUNDWATER, Salinity levels over 1,500 mg\L - 2000
Map 24.28: GROUNDWATER, Salinity levels over 1,500 mg\L - 2000

Source: Data based on NLWRA 2001.Australian Groundwater Provinces (2000) 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.


24.29 SUSTAINABLE YIELD GROUNDWATER, By level of salinity - 2000

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

Less than 1,500 mg/L
<500 mg/L
698
194
1,373
56
1,899
1,585
4,412
10,217
500-1,000 mg/L
3,928
827
995
229
1,061
767
287
8,093
1,000-1,500 mg/L
34
386
119
679
995
-
455
2,670
Total
4,660
1,407
2,487
964
3,955
2,353
5,154
20,980
1,500 mg/L and over
1,500-3,000 mg/L
812
244
113
253
1,468
178
139
3,208
3,000-5,000 mg/L
2
707
30
-
588
-
183
1,510
5,000-14,000 mg/L
440
201
63
762
841
-
-
2,307
More than 14,000 mg/L
-
797
-
-
371
-
-
1,168
Total
1,254
1,949
206
1,015
3,268
178
322
8,193
Total sustainable yield
5,914
3,356
2,693
1,979
7,223
2,531
5,476
29,173
Proportion (%)
Less than 1,500 mg/L
79
42
92
49
55
93
94
72
1,500 mg/L and over
21
58
8
51
45
7
6
28

Source: AWRC 1987a; AWRC 1987b; NLWRA 2001.


Water assets

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). 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 24.30). Most of Australia's dam capacity has been built since 1970 (graph 24.31).

Graph 24.30: WATER STORAGE CAPACITY OF LARGE DAMS - 2001



Graph 24.31: TOTAL WATER STORAGE CAPACITY OF LARGE DAMS



Previous PageNext Page

Bookmark and Share. Opens in a new window


Commonwealth of Australia 2014

Unless otherwise noted, content on this website is licensed under a Creative Commons Attribution 2.5 Australia Licence together with any terms, conditions and exclusions as set out in the website Copyright notice. For permission to do anything beyond the scope of this licence and copyright terms contact us.