The Murray–Darling Cap is a policy limiting irrigation diversions in the
Murray–Darling Basin
The Murray–Darling Basin is a large geographical area in the interior of southeastern Australia, encompassing the drainage basin of the tributaries of the Murray River, Australia's longest river, and the Darling River, a right tributary of ...
(
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
) to the volume of water that would have been diverted under 1993/94 levels of development.
It seeks to strike a balance between the amount of water available to
irrigators, the security of their water supply, and the environment. The Cap was introduced by the Murray–Darling Basin Ministerial Council in June 1995 after the release of the report titled "An Audit of Water Use in the Murray-Darling Basin".
The Murray–Darling system is a highly variable system in terms of inflows, and can vary between discharges of 1,600 GL and 53,000 GL. The average flow is 21,200 GL per year.
In the six years prior to 1994 an average of 10,800 GL had been diverted, mostly for agricultural purposes.
The diversion were having a significant impact on the
ecological health
Ecological health is a term that has been used in relation to both human health and the condition of the environment.
* In medicine, ecological health has been used to refer to multiple chemical sensitivity, which results from exposure to synthet ...
of the Murray-Darling river system.
The Cap limits surface water diversions to a long-term mean of 12,100 GL per year (383 m
3/s, 13,500 cu ft/s).
Seasonal adjustments are made for wet and dry years.
The introduction was seen as the first step in
water management
Water resources are natural resources of water that are potentially useful for humans, for example as a source of drinking water supply or irrigation water. These resources can be either freshwater from natural sources, or water produced artificia ...
methods that progressed towards sustainable development of the river system.
The Cap made water in the Basin a more valuable resource as it gave entitlements to its diversion more value and saw increased trade in these entitlements. While the Cap restrains further increases in water diversions, it does not constrain new developments, provided the water for them is obtained by using water more efficiently or by purchasing water from existing developments.
The Murray–Darling Basin Plan 2012 introduced Sustainable Diversion Limits (SDL), which will eventually replace the Cap. SDL came into effect in 2019, and will run in parallel to the Cap until it is fully implemented and the Murray–Darling Basin Agreement is amended or repealed.
See also
*
Murray Darling Basin Authority
*
Water security in Australia
References
External links
Murray-Darling Basin Cap on Diversion - Water Year 1997/98 - Striking the Balance Report Murray Darling Basin Commission: December 1998.
{{DEFAULTSORT:Murray-Darling Cap
Water resource management in Australia
Irrigation in Australia
Murray-Darling basin