Australian Natural Resources Atlas

Water resources - Allocation and Use - Victoria

Location Map

Victoria

How has Victoria's water use changed since 1985?

Comparison between the 1985 and 2000 'snapshot' assessments is difficult. Factors include the time between assessments (more than 15 years); seasonality and variability of climate; significant potential for changes in land use; and fluctuations in domestic and global market demands.

Water Use, Climate and the Audit Baseline Year - 1996/97

The baseline year for the Audit is the 1996/97 agricultural year starting on the 1st April and ending on 31st of March. For water use the data was compiled for the period 1 July 1996 to 30 June 1997 (water calendar year). When it is necessary to collect information for more than one year, the data collected must cover that year or, alternatively, appropriately adjusted to provide a best estimate for that year.

For water use data States and Territories were requested to provide a 5 yearly average value based on the 1996/97 year. Use figures were adjusted in areas where, due to climatic conditions, the water use was not considered to be 'average'.

Climate in 1996/97

During 1996 there was a transition from the weak large-scale climate controls to a strong El Ni?o condition after March 1997. This resulted in a drying over a large part of southern and eastern Australia. From July until September 1996 Victoria had unusually cold and wet weather. The remainder of the southern half of Australia was also wet for three months. Significant areas in south-west Queensland, western and central New South Wales, South Australia, western Victoria, and southern Western Australia had rainfall totals within the highest 10% on record.

During the summer of 1996-97, there was a very active monsoonal season in the tropical zones in western Australia and the Northern Territory. However, this finished abruptly and early, as El Ni?o developed rapidly in autumn 1997. From October 1996 very dry conditions prevailed over most of Victoria, the grain belts of South Australia and north-east Tasmania. Areas of southern Victoria through to south-east South Australia had the driest October to June period on record.

May 1997 brought rain to southern Australia and average to above average rain to parts of Queensland. There was some relief to farmers from the dry and hot conditions over southern Australia in early 1997. In parts of southern Victoria and south-east South Australia the driest October to June period was reported. (ABS Water Account, 2000)

Climate in 1983/84 (Water Review 85)

Water use in any particular year is affected by weather conditions. For much of Australia, the period, July 1983 to June 1984, was equivalent to a normal year in which water use was about average. In south-east Australia, however, abnormal weather patterns were experienced. In general, rainfall totals throughout Victoria were high during the first half of the year but were lower than average in the second half. These weather conditions, along with a continuing sensitivity to water use following the 1982/83 drought, had a marked effect on water usage. Although the 1982/83 drought that affected most of Victoria was broken by above-average rains early in the year, water restrictions in many urban areas were not lifted until much later in the year. Urban water use was therefore less than average, due both to the heavy rains and to the continuance of water restrictions.

The above-average rains in the first half of 1983-84 greatly reduced irrigation demands, and by mid-season virtually unrestricted supplies of water were made available to farmers (for example, 200% of water rights in the Goulburn-Murray Irrigation District). The drier conditions in the latter half of the year somewhat compensated for this, but total usage for the year was generally far less than average.

Rural usage was also less than average, again due to the early wet conditions and sensitivity about excessive water use following the 1982-83 drought. (DPIE, 1987).

Map of change in total water since 1985

Note:

Note: The change in water use volume from 1985 to 1996 does not always reflect factors affecting consumption patterns and volumes such as population growth, industry or land-use change or operational improvements. The observed difference may partly be attributed to differences in the approach and assumptions used to estimate water use within the river basin.

Total water use for the Snowy River Basin and East Gippsland Basin has not been reported as these volumes were not available for the NSW component of the basin.

A direct comparison between data reported for 1985 and 1996 cannot be made for the Murray Riverina Basin due to a change in the boundary definition of the Basin. For this current assessment the Murray Riverina Basin has been defined as the regulated stretch of the Murray River extending from Lake Hume to the South Australian border. In 1985 the Murray Riverina Basin is defined as an area on the New South Wales side of the Murray River, extending from Hume Dam to a point just upstream of the confluence with the Murrumbidgee River.

Chart of Proportion of total water use by consumptive classes
Basin NameUse in 1983-84 (GL /yr)Use in 1996-97 (GL /yr)% Change
VIC4,053 5,166 27
Avoca River 364012
Barwon River 1233182
Broken River 47389890
Bunyip River 61512,458
Campaspe River 198442124
East Gippsland 21-63
Glenelg River 4419
Goulburn River 50092084
Hopkins River 121415
Kiewa River 111538
Lake Corangamite 65-20
Latrobe River 81195141
Loddon River 8041,17646
Mallee 452363-20
Maribyrnong River 423486
Millicent Coast 84-53
Mitchell River 91239
Moorabool River 323953
Murray-Riverina 1,4081,91436
Otway Coast 413276
Ovens River 2040103
Portland Coast 22-3
Snowy River 3373-99
South Gippsland 101232
Tambo River 336
Thomson River 14022662
Upper Murray River 925186
Werribee River 2483246
Wimmera - Avon Rivers 45131191
Yarra River 83274,099

Note: The total surface water use reported for each river basin does not include the water consumption of the eleven major cities. The data for cities and river basins are reported in the State totals.

How are the surface water resources used and allocated in Victoria?

Chart of Proportion of surface water use by consumptive classes

Table: Surface water diversion and allocation 1996-97

Basin/SWMA NameAllocation (GL/yr)Diversion (GL/yr)Diversion: Allocation (%)
Victoria6,2845,9800
Avoca River 44100
Avon River 88100
Barwon River 464188
Broken River 3232100
Bunyip River 471123
Campaspe River 121121100
East Gippsland (Vic) 2142
Glenelg River (Vic) 737299
Goulburn River 1,9431,943100
Hopkins River 11767
Kiewa River 99100
Lake Corangamite 11100
Latrobe River 22216172
Loddon River 109109100
Maribyrnong River 10871
Mid-Murray River (Hume to SA Border) (Vic) 1,6391,639100
Millicent Coast (Vic) 11100
Mitchell River (Vic) 191262
Mitta Mitta River 835835100
Moorabool River 461736
Otway Coast 272074
Ovens River 2626100
Portland Coast 22100
Snowy River (Vic) 6339
South Gippsland 221254
Tambo River 7341
Thomson-Macalister Rivers 42834280
Upper Murray River (Vic) 44100
Werribee River 333398
Wimmera - Avon Rivers 9595100
Yarra River 46742190

Note: Allocation is not based on 1999-2000 estimates; Diversion based on five-yearly average 1996-97.

Note: In the table above, the total surface water use reported for each river basin does not include the water consumption of the eleven major cities. The data for cities are reported in the State totals. The volume diverted is the total volume of the SWMA's surface water resources diverted for use both within the management area and for export to other management area. The figures reported for the Mitta Mitta River and in the State totals includes the diversion and allocation to NSW of 814 GL/yr.

The total volume of surface water allocated for use in Victoria is 5469 GL, which represents 80% of the sustainable yield of 6862 GL for the State. An additional 814 GL is allocated for commitments to NSW. The total allocation of the State's resources represents 92% of the sustainable yield.

At present, approximately 5166 GL of surface water is used in Victoria annually. This represents 75% of the sustainable yield of the resource and 82% of the currently developed yield.

Water use in Victoria is dominated by irrigation, which uses 78%, or about, 4019 GL, of total extracted water on average each year. Urban and industrial use accounts for a further 17%, or 861 GL, of total use (approx. 60% of which occurs in Melbourne) and rural supplies for 5%, or about 286 GL. The urban use component comprises around 47% domestic use, 34% industrial/commercial, 6% for other uses such as parks and gardens, and 13% losses.

Most of the land under irrigation is located north of the Great Dividing Range and is supplied from the Goulburn and Murray Rivers. Approximately 40% of irrigation water is devoted to the production of pasture, which is used primarily to feed animals that provide meat and dairy products.

Please note: The tables set out below detailing Level 1 and Level 2 water use categories. The sum of the Level 2 water use volumes will not necessarily equal the total Level 1 water use volumes. This is primarily due to lack of more detailed water use data. However, where Level 2 use = Level 1 use then blank cells in the table does not indicate water use unaccounted for in these categories. 

Map of total surface water use in 1996

Table: Surface water use in Victoria 1996-97

Basin/SWMA NameIrrigation (GL/yr)Rural (GL/yr)Urban / Industrial (GL/yr)Total (GL/yr)In-situ (GL/yr)
Victoria4,0212868605,166no data
Avoca River 2016540no data
Avon River 471148no data
Barwon River 412933no data
Broken River 857329898no data
Bunyip River 51146151no data
Campaspe River 420176442no data
East Gippsland (Vic) 1111no data
Glenelg River (Vic) 2134no data
Goulburn River 8603527920no data
Hopkins River 71814no data
Kiewa River 72715no data
Lake Corangamite 1145no data
Latrobe River 482146195no data
Loddon River 1,10246291,176no data
Mallee (Vic) 3193213363no data
Maribyrnong River 212123no data
Millicent Coast (Vic) 0111no data
Mitchell River (Vic) 91312no data
Mitta Mitta River 201121no data
Moorabool River 132023no data
Otway Coast 36413no data
Ovens River 2741040no data
Portland Coast 2102no data
Snowy River (Vic) 2113no data
South Gippsland 52712no data
Tambo River 2123no data
Thomson-Macalister Rivers 17442179no data
Upper Murray River (Vic) 3114no data
Werribee River 2515883no data
Wimmera - Avon Rivers 288716131no data
Yarra River 32no data295327no data
Map of surface water use for irrigation in 1996 Map of areas where surface water allocation is greater than sustainable yield

How are Victoria's groundwater resources used and allocated?

The total groundwater use is estimated to be 622 GL/a, which includes 510 GL/a in the GMUs and a further 112 GL/a in the UAs. The predominant use in the UAs is for irrigation (60%), stock and domestic (20%), mine dewatering and urban use (16%) and in-situ uses (4%).

Based on the data for 1996/97, approximately 80% of the total allocated volume for groundwater is being used, with 160 GL of allocated groundwater not being used. However, more recent estimates indicate that this gap between allocation and use is closing, reflecting both an increase in demand for water and the decreasing availability of surface water supplies in many locations. 

"GMU"=Groundwater Management Unit "UA"=Unallocated Area

Province Use in 1983-84 (GL /yr)Use in 1996-97 (GL /yr) % changeCurrent Alloc (GL/yr)Current Use : Alloc (%)GMU / UA
Victoria198 622 215 1 7,072 GMU
67 100 UA
Gippsland 118316718790GMU
190UA
Lachlan 122517953834GMU
710UA
Murray 17647311,60746GMU
270UA
Otway Highlands no data1no datano datano dataGMU
10UA
Otways 121818633656GMU
330UA
Port Phillip 121141876GMU
90UA
Westernport no data13101286GMU
30UA
Map of total groundwater use in 1996 by province Map of groundwater allocated volume Chart of total groundwater use by use class

Table: Groundwater use in Victoria 1996-97

ProvinceIrrigation (GL/yr)Rural (GL/yr)Urban / industry (GL/yr)In-situ (GL/yr)Total (GL/yr)SY (GL/yr)
Victoria43155 128 11 622 3,658
Gippsland 93983187629
Lachlan 14150352261,491
Murray 72227167702,388
Otway Highlands no data1no data186
Otways 17517272181,817
Port Phillip 124622216
Westernport 9231339
Map of groundwater use for irrigation in 1996 by groundwater province

Surface and groundwater interactions

Current Status of Conjunctive Management in Victoria

Groundwater is the minor player in the supply of the State's water, with some 11% of total water use being drawn from groundwater resources. However, it is now being increasingly recognised that, in many areas, groundwater substantially contributes to the baseflow of surface streams, and that groundwater use can impact upon the availability of surface water resources (and vice versa).

The Water Act 1989 prescribes in considerable detail the setting up of Groundwater Supply Protection Areas (GSPAs), and the development of Groundwater Management Plans for these areas. On the other hand, it is silent on the question of Streamflow Management Plans (SMPs), which are developed in an informal arrangement between NRE and the rural water authorities. It is recognised that part of the function of SMPs is to apportion the baseflow between consumptive use and the environment.

Ideally, where there is a significant interaction between surface and groundwater systems, there should be some integration of groundwater and surface water planning and management processes.

The only conjunctive management of surface and groundwater resources currently in place in Victoria is in relation to 'on-farm' water allocations in some locations, where total water use cannot exceed a set allocated volume, regardless of the source of the water. Goulburn Murray Water currently has such a policy in place in some irrigation districts, particularly in those areas covered by salinity management plans, where infiltration of water to the groundwater can cause rising water tables and, subsequently, increased land salinisation. The implementation of the policy is still in its infancy and the data required to enforce this policy is currently not readily available (pers. comm. D Morrison (GMW) October 2000).

While current SYs for some GMUs take into consideration baseflows to rivers and lakes, and have reduced SYs to allow for the maintenance of these surface water flows, these allowances have been made on the basis of very limited information. The impact of groundwater use on river baseflow needs to be monitored to determine whether the assumptions that have been made are correct, and what management actions are required in order to ensure that surface water resources are not impacted upon by the extraction of groundwater resources.

Impediments to Conjunctive Management of Surface and Groundwater Resources

Impediments to the conjunctive management of surface and groundwater resources are:

Priorities for Conjunctive Management

Rural water authorities have identified streams that they consider require investigation as a matter of priority because of their potential interaction with groundwater systems. Monitoring is required in these situations to determine the connection between surface water and groundwater.

For the purposes of the Audit, a further assessment was made of the priorities for considering conjunctive management of surface and groundwater resources. The listed priorities are based on the categorisations of the various GMUs and SWMAs relative to current use, and on the degree of physical connection between surface water and groundwater systems. Of the 63 GMUs in Victoria, 44 are physically connected to surface water resources.

Having prioritised GMUs and SWMAs in relation to the need for conjunctive management, the next steps would involve specifying and prioritising particular river reaches and the aquifers connected to those particular reaches. Information currently available indicates that most aquifers are connected either in part to a river reach, or have variable connection along a stream's length. More detailed information would be required prior to any conjunctive use policy or management process being put in place. This would include information on the physical processes and connections between surface water and groundwater systems, on the impacts that high use of groundwater or surface water has on the other resource, and an estimate of the joint 'sustainable yield' for the combined systems. As each case differs from the next, management strategies would need to be tailored to particular situations.

Further information

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