Transcript murray-darling.ppsx

Sustainable Water Supply
• How do human activities influence water
supply and demand?
Water supply and demand –
competing uses.
Where is it?
• The Murray-Darling Basin is 3,375 km long,
drains one-seventh of the Australian land mass,
and is currently by far the most significant
agricultural area in Australia. The name of the
basin is derived from its two major rivers, the
Murray River towards the mouth in the SW and
the Darling River to the source in the NE .
Geography of the area
• Most of the 1,061,469 km² basin is flat, low-lying
and far inland, and receives little rainfall. The
many rivers it contains tend to be long and slowflowing, and carry a volume of water that is large
only by Australian standards.
• The rivers have very low gradients over most of
their length, which cause them to flow slowly as
they meander across the vast inland plains.
Water Demands
• It contains over 40% of all Australian
farms, which produce wool, cotton,
wheat, sheep, cattle, dairy produce,
rice, oil-seed, wine, fruit and
vegetables for both domestic and
overseas markets. As Australia's most
important agricultural region, the
Basin produces one third of
Australia's food supply and supports
over a third of Australia's total gross
value of agricultural production.
• Three quarters of Australia's irrigated
crops and pastures are grown in the
Basin.
Water demands
• The Murray-Darling Basin is also very
important for rural communities and
Australia's economy. Three million
Australians inside and outside the MurrayDarling Basin are directly dependent on
its water. About 85 per cent of all
irrigation in Australia takes place in the
Murray-Darling Basin, which supports an
agricultural industry worth more than $9
billion per annum.
• The
long-term
productivity
and
sustainability of the Murray-Darling Basin
is, however, under threat from overallocated water resources, salinity and
climate change.
Australia: Water hogs leave Darling
high and dry downstream
Thanks to the drought and too much water
being taken upstream, a once great river has
been reduced to use as a cricket pitch
The water crisis
The Murray-Darling Basin has reached record-low
levels. The main reason for this is that Australia is
experiencing its worst drought in possibly a thousand
years. According to the Bureau of Meteorology,
drought is part and parcel of life in Australia, simply
because of its geographical location. Nevertheless,
with climate change threatening to make matters
worse, finding a solution to the water crisis is
becoming more urgent.
What are the demands?
• Industrial and domestic use
The industrial and domestic needs for water have
meant that regulation and control of the river’s natural
flow has affected its wetlands fauna and flora. The use
of locks and dams interrupts the geological course of
the river, restricting water in some areas where it is
urgently needed, while other areas receive more water
than they normally would in a heavy rainfall season.
This has affected the breeding cycles of animals and
plants adding to a decrease in water quality.
• The rise of salinity
The river system already has serious problems with
salinity. Agriculture is mostly to blame for this—land
clearing increases the amount of naturally occurring
salt rising to the river’s surface and irrigation uses
groundwater with high saline levels. It is estimated that
salinity costs the users of the Murray River $47 million
each year. This is due to lower productivity; loss of
recreation; and the impacts on biodiversity caused by
poor water quality and shrinking floodplains and
wetlands.
• Chemical pollution
Apart from pollution in the form of salt and clay
particles, the water quality of the Murray-Darling
Basin is threatened by sewage and storm-water
pollution, and fertilizer and pesticide runoff.
Pollution from irrigated dairy pastures has also
produced faecal bacteria in the water. There has
been a reduction in pollution over the last
decade, however there are still concentrations of
some chemicals.
Time for change
• At the 3 July 2008 meeting of the Council of
Australian Governments (COAG), the Prime
Minister, Premiers of New South Wales,
Victoria, South Australia and Queensland and
the Chief Minister of the Australian Capital
Territory signed an Intergovernmental
Agreement on Murray-Darling Basin Reform.
5 (a) (i) Use Resource 3a
to describe factors that
may have accounted for
the lack of river flow
through the mouth of
the Murray River in
2002. (10)
Answers
• Thirty major dams and over 4, 000 weirs clutter the Murray-Darling
Basin's rivers. Placing too many structures across rivers causes changes
to flow patterns, loss of beneficial flooding, erosion of river banks and
also salinity problems.
*a weir is a small dam generally under four metres in height. Weirs
prevent or reduce the migration of native fish.
• Population increase
• Low lying relief
• Increased diversions
• Rainfall deficiency
• Varied climatic conditions
5 (a) (ii) Use Resource 3b
to explain why Adelaide
has a problem with the
quality of drinking water
extracted
from
the
Murray River. (5)
5 (b) Identify the main conflicts
that have arisen through the
increased demand for water in
this drainage basin. Use
Resource 3c. (10)
Answers
• Irrigation (farmers, residents) - About 85 per
cent of all irrigation in Australia .
• Aborigines – Spiritual value destroyed.
• Natural heritage – holds key to history of area,
should be preserved.
• Conservationists – massive environmental
impacts.
• North - South conflicts of use.
5 (c) The use of water in the Murray-Darling
Basin is no longer sustainable. Use Resources
3s, 3b and 3c to evaluate the importance of
the different factors contributing to this
problem (10)
Answers
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Dams/weirs
Diversions
Lack of rain
Increased population
Lower flow
Many states in the basin
Low lying relief
Increasing demand for food = increased irrigation
Increasing population = further dmands
Environmental damage increasing.
Increasing salinity – water unusable.
Poor, variable and unreliable climate.
• 5 (d) Resource 3d shows current methods of
addressing the problems of sustainable water
use. Assess their merits and limitations. Use
all Resource 3 to help you answer. (15)