Sustainable development
Water conservation (approx. 4' 57")
Australia is the driest populated continent on Earth, with only one percent of the world’s
water. It’s also a major agricultural producer, so one of the most serious environmental
challenges it faces is the conserving of water.
Despite Australia’s small population of 20 million people, a low and variable rainfall means
that most of the water in southern areas is targeted for use, mainly in agriculture. In many
river systems, such as the Murray–Darling Basin, it’s a challenge to have enough water left
flowing to maintain ecosystems and to support the needs of industries and communities.
The Murray–Darling Basin provides drinking water for more than three million people. It’s
also a home for many native creatures as well as supplying water for agriculture. The
Murray–Darling Basin lies to the west of the Great Dividing mountain range and has two
main rivers, the Murray River and its tributary, the Darling River. One of the world's major
river systems, its length from its source in the Queensland mountains to its mouth at the sea in
South Australia is 3370 kilometres. In comparison, Japan’s Shinano River is 367 kilometres
in length.
The catchment area is huge, covering 14 per cent of the whole of Australia, about one million
square kilometres. The whole land area of Japan would fit into it nearly three times!
There is another difference between the Shinano River and the Murray-Darling rivers. The
Shinano River runs steeply and rapidly from the mountains to the sea, the Murray–Darling
Rivers wind their way slowly inland from the Great Dividing Range across many different
types of environments before finally reaching the sea.
Managing the Basin is a delicate matter: precious ecosystems must be protected and the
conservation of water for other uses can endanger them. Amongst the varied ecosystems of
the Basin are around 30,000 wetlands which are important breeding grounds for birds from as
far away as Japan. There are also large river red gum forests on the flood plains of the major
rivers of the Murray–Darling, which are a home to wildlife and provide breeding grounds for
native fish and birds.
Floods were once frequent, but the damming of the headwaters for power and water storage
and the creation of weirs along the river system has stopped this. The river red gums need
floods to regenerate and many animals rely on flooding to breed, so controlling floods is not
necessarily a good thing. Major ecosystems such as these vast forests could eventually die out
if they do not receive sufficient water.
There are also many forms of land degradation which affect the water catchment, including
soil erosion and soil salinity. In Australia, soils naturally contain a lot of salt which has been
deposited deep in the ground over tens of millions of years. When salts are dissolved by rising
groundwater, they are carried into the rivers or come to the soil surface, killing fish and
plants.
Over the last century, land clearance for farming increased salinity and so in areas where it is
a problem, hundreds of millions of trees are being planted to try to lower the watertable. In
some areas, salt tolerant plants are being trialled while enterprising farmers are using salty
ponds for aquaculture or extracting the salts from the soil to sell. Soil erosion has been
dramatically reduced by changes in farming practices.
The Murray–Darling Basin Ministerial Council and Commission is responsible for
coordinating the management of the area’s natural resources. One of their most successful
measures has been to put a long term limit on the amount of water that can be diverted from
the river. It is up to each State to then decide how this water is shared between consumers and
the environment each year. During dry years, these allocations have been reduced.
There is hope for the future. Governments are working on new regulations that will increase
the amount of water and distribute it more fairly, to maintain the ecology of the rivers and the
water quality. New technologies are being developed to reduce water consumption in
agriculture and scientists are experimenting with damming and releasing water to create
manageable and much needed flooding.
Most importantly, at all levels of government, in all forms of industry, and in the wider
community, people recognize that there needs to be strategies for handling this major
environmental challenge.