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Murray–Darling Basin

                                                                                                   

Physical Information

                             

This page provides details about the region, its water resources, land use and water-related infrastructure.

 

 

General Description

Area: 1,055,600 km2 ( Australian Bureau of Rural Science 2010 )

Population: 2.0 million ( Australian Bureau of Statistics 2008)

The Murray–Darling Basin (MDB) is defined by the catchment areas of the Murray and Darling rivers and their many tributaries. The MDB covers three-quarters of New South Wales, more than half of Victoria, significant portions of Queensland and South Australia, and all of the Australian Capital Territory (shown in figures P1 and P2). It contains:

  • around 440,000 km of rivers, of which 40,000 km are major
  • some 30,000 wetlands, covering an area of around 25,000 km²
  • about 60,000 km² of floodplain area, which represents approximately 6% of the MDB.

Figure P1. Location map of the Murray–Darling Basin within Australia

Figure P1. Location map of the Murray–Darling Basin within Australia (source for the boundaries of the MDB: Australian Government Department of Sustainability, Environment, Water, Population and Communities)

Figure P2. Contextual map of the Murray–Darling Basin

Figure P2. Contextual map of the Murray–Darling Basin (source for the boundaries of the MDB: Australian Government Department of Sustainability, Environment, Water, Population and Communities)


Major rivers in the MDB include (Geoscience Australia 2010):

  • Murray River, which forms the border of Victoria and New South Wales, and flows east to west for 2,375 km
  • Darling River, which begins in northern New South Wales and flows 2,844 km (including its major tributaries – the Culgoa, Balonne and Condamine rivers) southwest to its junction with the Murray River at Wentworth
  • Murrumbidgee River, which flows 1,485 km from southern New South Wales, through the Australian Capital Territory and then westwards to the Murray River
  • Lachlan River (1,339 km), which starts in the central highlands of New South Wales and flows southwest to the Murrumbidgee River
  • Goulburn River, which flows 654 km from central northern Victoria northwards into the Murray River.
The MDB is a complex, interconnected river system rather than a series of separate catchments. However, its diverse climate and landscape, and the presence of artificial structures means that not all parts of the system are connected to the same extent. For example, rivers such as the Paroo, Lachlan and Wimmera only rarely contribute flows further downstream.

Figure P3. Map of major rivers of the Murray–Darling Basin

Figure P3. Map of major rivers of the Murray–Darling Basin (source for the boundaries of the MDB: Australian Government Department of Sustainability, Environment, Water, Population and Communities)

Description of the region

The MDB is defined in Section 18A of the Water Act 2007 (Cwlth). It includes all water resources within or beneath the MDB, but does not include groundwater that forms part of the Great Artesian Basin (GAB).

For the National Water Account 2010 (the 2010 Account), the MDB region (see Figure P2) is defined as all the surface water connected to the channel network and all the groundwater (excluding any water in the GAB) located within the geographical boundaries of the MDB specified by the Australian Capital Territory, less:

  • the areas drained by the Snowy Mountains Hydro-electric Scheme storages that are located inside the legal MDB’s boundaries
  • the towns of Port Elliot and Middleton in South Australia.

In particular, the following elements are not included in the MDB region:

  • private reservoirs, such as landscape catchment reservoirs (also known as ‘farm dams’) and other private reservoirs used to harvest floodwaters, as they constitute water abstracted before it reaches the connected river channels or water owned by the users
  • water in utility infrastructures (pipes, open channels, tanks) used to transfer, supply and distribute water to users.

The MDB region presents a varied landscape, from semi-arid ephemeral river systems in the north to highly regulated river systems in the south fed from the Australian Alps. To the east and south, the highlands of the Great Dividing Range form the limit of the MDB region, while in the north, west, and southwest, the boundaries are much less distinct. The greater proportion of the MDB region is made up of extensive plains and low undulating areas; most of them are less than 200 m above sea level.

Land Use

Major towns and cities within the region

The major population centres of the MDB region (Australian Bureau of Statistics 2010) and their population (as at end of 2009) include:
  • Canberra–Queanbeyan – 403,118
  • Albury–Wodonga – 104,609
  • Dubbo – 37,491
  • Orange – 38,685
  • Tamworth – 46,695
  • Wagga Wagga – 58,046
  • Bendigo – 89,995
  • Mildura – 50,042
  • Shepparton – 48,926
  • Toowoomba – 128,600.
There are also a number of smaller urban centres throughout the MDB region such as Bathurst, Griffith, Echuca, Moree, Horsham, Wangaratta, Warwick and Murray Bridge.

Land use activity

The MDB region contains approximately 40% of all Australian farms (by number), producing wool, cotton, wheat, sheep, cattle, dairy products, rice, oilseeds, wine, fruit and vegetables for domestic and overseas markets (source: Guide to the Proposed Basin Plan).

The major land use activities in the MDB region are shown in Table P1 (Australian Bureau of Rural Science 2010). Figure P4 shows the distribution of these land uses within the region.

 

Table P1. Major land use activities in the MDB region
Land use activity
Area (km2)
Total area of region (%)
Conservation and natural environments
107,600
10
Dryland agriculture
133,300
13
Forestry
34,000
3
Grazing
727,800
69
Irrigated agriculture
24,700
2
Mining
300
<1
Other intensive uses
1,200
<1
Urban
14,300
1
Water
12,400
1
Total
1,055,600
100

 

Figure P4. Map of land use in the MDB region

Figure P4. Map of land use in the MDB region (source: Australian Bureau of Rural Science 2010; source for boundaries of the MDB region: Australian Government Department of Sustainability, Environment, Water, Population and Communities)

Land use activities that are major water users in the MDB region are urban supply and irrigated agriculture.


Significant Aquatic Environmental Systems

The MDB contains 16 Ramsar-listed wetlands of international importance:
  • Banrock Station wetland complex (South Australia)
  • Barmah Forest (Victoria)
  • Coorong and Lakes Alexandria and Albert (South Australia)
  • Currawinya Lakes National Park (Queensland)
  • Fivebough and Tuckerbil swamps (New South Wales)
  • Ginni Flats (Australian Capital Territory)
  • Gunbower Forest (Victoria)
  • Gwydir Wetlands (New South Wales)
  • Hattah–Kulkyne Lakes (Victoria)
  • Kerang Lakes (Victoria)
  • Lake Albacutya (Victoria)
  • Macquarie Marshes Nature Reserve (New South Wales)
  • Narran Lake Nature Reserve (New South Wales)
  • New South Wales Central Murray state forests
  • Paroo River wetlands (New South Wales)
  • Riverland (South Australia).
The MDB region also contains nationally important wetlands, listed in the Directory of Important Wetlands in Australia.

Water Resources

The water resources in the MDB region are highly developed, as illustrated by the following statistics based on a long-term average of 114 years (1895–2009) (source: Guide to the Proposed Basin Plan):

  • Approximately 42% of the total surface water run-off to the MDB region is diverted for consumption, while 58% currently remains in the environment.
  • The majority of the surface water consumed in the MDB region, 10.9 million ML/year, is diverted from the watercourse and used for irrigation and urban supply. In addition 2.7 million ML/year are intercepted by local catchment reservoirs and forestry plantations that intercept run-off before it reaches the watercourse.
Around 1.7 million ML of groundwater are consumed each year from the MDB region’s water resources (source: Guide to the Proposed Basin Plan).

A Murray–Darling Basin Cap (the Cap) was established in 1995 to limit the volume of surface water that could be diverted in the MDB region in any year to that based on the 1993–1994 levels of development. The Cap does not place a restriction on groundwater extraction. See ‘Operating rules and constraints’ within the ‘Water rights’ section for further information on the Cap.

Surface Water

The southern part of the MDB region is considered to be mostly a regulated system. The reservoirs in the three major southern rivers – the Murrumbidgee, Murray and Goulburn – are used to provide regulated flows downstream as far as the lower lakes.

The northern part of the MDB region consists mostly of unregulated systems, where many of the rivers and streams are ephemeral and fed by seasonal rainfall. Generally, water users in much of the northern MDB region must rely on collecting water during floods and storing it on-farm for later use.

The accounting reports for the 2010 Account present details on the surface water volumes for the 19 regions (see Figure P5) as defined for the proposed Basin Plan where data were available.


Figure P5. Map of Murray–Darling Basin Plan’s regions

Figure P5. Map of Murray–Darling Basin Plan’s regions (source: Murray–Darling Basin Authority)

 

Major storages

The total storage capacity (including dead storage) for the 50 major storages (excluding weirs) within the MDB region for which data are available for the 2010 Account is 23,097,214 ML. A full list of these storages and their individual storage capacities can be found in:

  • Line item 1.1 Storages—entitlement system
  • Line item 1.5 Connected surface water—other lumped.

 

Streamflow summary

Figures P7 to P9 show streamflow patterns, volumes and variations at three major rivers in the region for the following streamflow gauging stations shown in Figure P6:

  • Murray River at Doctors Point (Albury) (Station ID 409017)
  • Darling River at Bourke (Station ID 425003)
  • Ovens River at Peechelba (Station ID 403241).

The Darling River at Bourke represents the unregulated northern MDB region.

The Murray River at Doctors Point (Albury) represents a regulated reach of the Murray downstream of the major regulating reservoirs.

The Ovens River at Peechelba represents a largely unregulated major river in the southern MDB region.

 

Figure P6. Map of the streamflow gauging station locations used to develop flow charts

Figure P6. Map of the streamflow gauging station locations used to develop flow charts (sources: Bureau of Meteorology and Murray–Darling Basin Authority)

 

Figure P7. Graph of total monthly flow during 2009–10 compared against long-term percentiles for the Murray River at Doctors Point

Figure P7. Graph of total monthly flow during 2009–10 compared against long-term percentiles for the Murray River at Doctors Point (Albury) (Source: Bureau of Meteorology)

 

Figure P8. Graph of total monthly flow during 2009–10 compared against long-term percentiles for the Darling River at Bourke

Figure P8. Graph of total monthly flow during 2009–10 compared against long-term percentiles for the Darling River at Bourke (Source: Bureau of Meteorology)

 

Figure P9. Graph of total monthly flow during 2009–10 compared against long-term percentiles for the Ovens River at Peechelba

Figure P9. Graph of total monthly flow during 2009–10 compared against long-term percentiles for the Ovens River at Peechelba (Source: Bureau of Meteorology)

 

Water transfers

In a number of locations, water is transferred into or out of the region, as well as from one catchment to another within the region (see Figure P10).

Figure P10. Map of water transfers into, out of, or between catchments within the MDB region

Figure P10. Map of water transfers into, out of, or between catchments within the MDB region (sources: Bureau of Meteorology and Murray–Darling Basin Authority)

 

Major transfers into the MDB region are from:

  • the Snowy Mountains Hydro-Electric Scheme into the Murrumbidgee and Murray rivers (see Line item 7.1 in the water accounting statement notes for more details)
  • the Glenelg catchment to the Wimmera system
  • Perseverance, Cressbrook and Wivenhoe reservoirs (through Cressbrook Reservoir, which started in 2010) in the Brisbane valley to Toowoomba in the Condamine–Balonne region.

Transfers out of the MDB region include diversion of water from the:

  • South Australian River Murray to supply metropolitan Adelaide and country towns
  • Macquarie River water sources (Fish River Scheme) to the Blue Mountains region in Sydney
  • Goulburn River system via the North–South Pipeline to supply Melbourne (which began in 2010)
  • Water transfers from the Goulburn-Broken region to Ballarat (in the Barwon River Basin) via ‘Goldfields Superpipe’ since May 2008
  • Water transfers from the Goulburn-Broken region (from Silver and Wallaby creeks which are tributaries of the Goulburn River, not shown in Figure P10) to the Melbourne urban supply system.

Channels and pipelines in the river system of the southern MDB region allow water to be moved and traded from one catchment to another. For example, the Waranga Western Channel delivers water from the Goulburn River to the Campaspe, Loddon and Wimmera–Avoca catchments.

 

Groundwater

The groundwater systems of the MDB region can be categorised into three broad types:

  • alluvial sedimentary systems (Quaternary/Tertiary)
  • fractured basement rock systems (Paleozoic)
  • sediments of the Great Artesian Basin (Cretaceous/Jurassic).
Alluvial sedimentary aquifers are the most important for groundwater extraction, with nearly all of the extracted groundwater (more than 95%) coming from these aquifers. The groundwater systems have relatively high waterholding capacity and hydraulic conductivity, and therefore are suited to extraction for use in irrigation and urban water supply. Groundwater quality is another significant consideration – water quality typically deteriorates down the groundwater flow path, constraining groundwater use to areas with acceptable water quality (primarily determined by low salinity). In the 2010 Account, components of an annual groundwater balance were estimated for the groundwater management units (GMUs) in alluvial sedimentary aquifers that are listed in Table P2 and shown in figures P11, P12 and P13. A GMU was defined by the 2000 National Land and Water Resources Audit as a ‘hydraulically connected groundwater system that is defined and recognised by Territory and State agencies’ (Richardson et al. 2008).

 

Table P2. List of groundwater management units with estimated groundwater balance in the 2010 Account

No.

Groundwater management unit (GMU)

State
1
Lower Gwydir Alluvium

NSW

2
Lower Lachlan Alluvium

NSW

3
Upper Lachlan Alluvium

NSW

4
Lower Macquarie Alluvium

NSW

5
Lower Murray Alluvium

NSW

Lower Murrumbidgee GMUs – sum of GMUs 6 & 7
6
Lower Murrumbidgee Deep Groundwater source

NSW

7
Lower Murrumbidgee Shallow Groundwater source

NSW

8
Mid Murrumbidgee Alluvium

NSW

9
Lower Namoi Alluvium

NSW

10
Upper Namoi Alluvium

NSW

Katunga–Campaspe GMUs – sum of GMUs 11–13
11
Campaspe Deep Lead Water Supply Protection Area

Vic

12
Katunga Water Supply Protection Area

Vic

13
Shepparton Irrigation Water Supply Protection Area

Vic

14
Mid Loddon Water Supply Protection Area

Vic

Lower Murray–Darling Basin GMUs – sum of GMUs 15–27
15
Balrootan (Nhill) Groundwater Management Area

Vic

16
Goroke Groundwater Management Area

Vic

17
Kaniva TCSA Groundwater Management Area

Vic

18
Murrayville Water Supply Protection Area

Vic

19
Nhill Groundwater Management Area

Vic

20
Telopea Downs Water Supply Protection Area

Vic

21
Angas–Bremer Prescribed Wells Area

SA

22
Coorong

SA

23
Ferries–McDonald

SA

24
Mallee Prescribed Wells Area

SA

25
Murraylands

SA

26
Peake, Roby and Sherlock Prescribed Wells Area

SA

27
River Murray Prescribed Water Course

SA

NSW = New South Wales; SA = South Australia; Vic = Victoria

 

Figure P11. Map of groundwater management units considered for calculations in the the 2010 Account

Figure P11. Map of groundwater management units considered for calculations in the the 2010 Account (source for boundaries of the MDB region and GMUs: Australian Government Department of Sustainability, Environment, Water, Population and Communities, and Murray–Darling Basin Authority)

 

Figure P12. Map of the groundwater management units (GMUs) grouped by the 2010 Account into the lower Murray–Darling Basin GMUs

Figure P12. Map of the groundwater management units (GMUs) grouped by the 2010 Account into the lower Murray–Darling Basin GMUs (source for boundaries of the MDB region and GMUs: Australian Government Department of Sustainability, Environment, Water, Population and Communities, and Murray–Darling Basin Authority)

 

Figure P13. Map of the groundwater management units (GMUs) grouped by the 2010 Account into the Lower Murrumbidgee GMUs and Katunga–Campaspe GMUs

Figure P13. Map of the groundwater management units (GMUs) grouped by the 2010 Account into the Lower Murrumbidgee GMUs and Katunga–Campaspe GMUs (source for boundaries of the MDB region and GMUs: Australian Government Department of Sustainability, Environment, Water, Population and Communities, and Murray–Darling Basin Authority)

 

In most fractured rock areas of the MDB (see Figure P11), groundwater use is limited to stock and domestic supply. Furthermore, in fractured rock areas, the annual change in groundwater storage and annual groundwater flow out of the area is much less significant to regional water balance. A groundwater balance in these areas is not explicitly estimated in the 2010 Account.

The GAB contains confined aquifers at depth and the confining layers at or near the land surface. It underlies about one-third of the MDB in the northwest (Figure P11). The GAB is a large geological basin that extends beyond the MDB drainage basin boundary to the north and west. It is recharged in small areas of the MDB (along the southeastern edge of the GAB) where the aquifer layers are exposed at the land surface. The GAB is not considered to be part of the MDB water balance because the GAB aquifers are effectively hydraulically disconnected from near-surface systems in the MDB. Groundwater extraction and leakage from the GAB to the MDB are not represented in the 2010 Account, but may be represented in the future as an interbasin transfer.

In the areas where the GAB confining layer is near or at the land surface (shown in Figure P11 as part of the area identified as ‘Great Artesian Basin Sediments’), storage is limited to the near-surface soil zone and is lost from this zone almost entirely as evapotranspiration. Thus there is no need to evaluate change in groundwater storage in these areas to establish an annual regional water balance in the MDB. In the areas overlaying the GAB – where the confining layer does not outcrop – there are some shallow alluvial areas associated with drainage lines. These were also not considered in the water balance evaluation.

Groundwater was explicitly quantified only for the GMUs that had the largest volumes of water stored and where extraction was substantial (see figures P11 to P13, above).

More details about the groundwater resources within the MDB region are available in the Groundwater note.

Other water resources

Across the MDB region, many towns and urban centres return treated urban wastewater to the river for subsequent use downstream. For example, on the Murrumbidgee, average returns to connected surface water from Canberra are more than half of the Australian Capital Territory diversions from the river. Returns may also flow from irrigation channels and infrastructure back to the rivers.