Quick Facts about the MDB
For more in depth information about the Murray-Darling Basin visit http://mdba.gov.au/explore-the-basin
- Catchment area for the Murray and Darling rivers and their tributaries
- Total of 23 river valleys
- Basin area over 1 million square kilometres
- 14% of total area of Australia
- Annual average rainfall 530,618 gigalitres
- 94% of rainfall evaporates; 2% drains into the ground; 4% ends up as runoff
- Basin generates 40% of the national income derived from agricultural production
- Produces 61% of Australian cereals grown for grain, 94% of oranges, and 63% of apples
- Supports 27% of the nation's cattle herd, 47% of sheep, and 62% of pigs
Location and area
The Murray-Darling Basin is the catchment for the Murray and Darling rivers and their many tributaries. Extending from north of Roma in Queensland to Goolwa in south Australia, it includes three-quarters of New South Wales and half of Victoria. In total there are 23 river valleys in the Basin, covering over 1 million square kilometres, or 14% of Australia. The Basin also contains important groundwater systems.
Average annual rainfall in the Basin is 530,618 gigalitres (1,000 times the volume of Sydney Harbour). Of this, 94% evaporates or transpires through plants, and 2% drains into the ground, leaving only 4% as runoff.
There is considerable variation in rainfall runoff from one part of the Basin to another, and this variation bears little relationship to catchment size. The catchments draining the Great Dividing Range on the south–east and southern margins of the Basin contribute most to total runoff. For example, the Murrumbidgee and Goulburn, Broken and Loddon river catchments account for 35% of the Basin's total runoff, yet they cover only 12% of its area. On its own, the Upper Murray catchment accounts for 17.3% of runoff, from only 1.4% of the Basin.
Many of the Basin's natural resources are of high environmental value. Its wetlands are extensive and perform essential hydrological, biological and chemical functions, which support and maintain the productivity and health of the river systems. A number of the Basin wetlands are recognised under the Convention on Wetlands of International Importance (otherwise known as the 'Ramsar Convention').
Home to more than two million people, the Basin supports many regional service centres and agricultural communities, as well as Canberra, the nation's capital. Outside the Basin, a further 1.3 million people depend on its water resources, including Adelaide with the largest population base reliant on Basin water resources.
Over 40 Aboriginal nations (21 Aboriginal Nations in the Northern Basin, 23 in the Southern Basin), live in the Basin and practice a rich cultural heritage based on the Murray–Darling river systems.
The Basin is Australia's most important agricultural area, producing over one–third of Australia's food supply.
The Basin generates 39% of the national income derived from agricultural production. It produces 61% of Australian cereals grown for grain (including 100% of rice), 94% of oranges, and 63% of apples. The Basin supports 27% of the nation's cattle herd, 47% of sheep, and 62% of pigs.
In Australia, irrigated land is 0.5% of total agricultural land. In the Basin, irrigated land is 1.5% of agricultural land. The Basin includes 66% of Australia's irrigated agricultural land.
Storing and distributing water
Water availability in the Murray–Darling Basin is subject to large variations, throughout the year, between years and over longer periods.
In the last 100 years, life in the Murray–Darling Basin has been transformed by the construction of major water storages on the rivers. The total volume of publicly managed water storage capacity in the Basin is just over 22,200 gigalitres. The Murray–Darling Basin Authority is responsible for managing about one–third of that volume – with major storages at the Dartmouth Dam, Hume Dam, Lake Victoria, Torrumbarry Weir, the Menindee Lakes and other river regulatory structures.
These storages have made it possible to store water during wet periods and release it as needed during summer or in droughts.
For more information download a copy of the MDBA's brochure 'The Murray-Darling Basin'
MDBfutures is supported by the Australian Government's Collaborative Research Networks program.