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There will never be any more freshwater on Earth thanthere is now. No new water is being made and water cantescape from the Earth. The water we use is recycled overand over again.
The water cycle is the simplest natural cycle on Earth. Solarenergy evaporates water from the ocean, lakes and rivers.Millions of litres of water rise into the atmosphere as an
invisible gas - water vapour. This process is calledevaporation.
As the water vapour is pushed over the land by winds andrises over mountains, the water vapour cools and turns backinto tiny water droplets, forming clouds. The dropletsjoining together is termed condensation. These droplets fall
to earth as rain (precipitation). The rain runs into streams and rivers, which eventually flow
into lakes or the sea and the cycle begins all over again.
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Australia is a dry country with very limited
water resources.
Avg. rainfall of 469 millimeters, Australia is
the driest habitable continent on Earth- onlyAntarctica is drier
70% of Australia is classified as arid with
little or no precipitation.
Highly variable climate- rain can fall indeluges or not at all
10 years- 3yrs of good rainfall, 4yrs of
average rainfall and 3yrs of poor rainfall
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Rainfall distribution is uneven
Some parts of Australia receive large
amounts of rain, while other areas receive
very little rain Rainfall is seasonal
Tully- annual rainfall
of 4000 millimetres
Lake Eyre- average
annual rainfall 100
millimetres
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Evaporation in Australia is so high and thetopography is so flat, that water flows out
from the land to the sea in only just over
half of the continent- the rest flows inwards
towards the middle.
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Australia has the smallest amount of run off-
water entering streams, rivers and dams- of
any country on Earth. It is this small amount
of run-off that makes the country so dry. Thismeans little usable water ends up in rivers.
Only about 48 millimeters of Australias
average rainfall runs off as surface water
(i.e. along the surface). This is the same
amount as New Zealand, even though
Australia is 28 times larger in area.
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80% of the water used by Australians is obtainedfrom surface water and 20% from ground watersources.
Australians are amongst the worlds biggest
consumers of water. We use about 350 liters perperson per day. Only about 2 liters of the 350liters used is actually drunk
Half the amount is used on the garden and therest is used in the toilet, bathroom, laundry andkitchen. With population increases, the demandfor water will continue to rise. Most urban areasin Australia already rely on dams for their watersupply.
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A drainage basin is an area of land wheresurface water from rain and melting snowor ice converges to a single point, usuallythe exit of the basin, where the waters
join another waterbody, such as a river,lake, reservoir, estuary, wetland, sea, orocean
Two of the largest drainage basins inAustralia are the MurrayDarling Basinand the Lake Eyre Basin, which eachcover an area of over 1 million squarekilometers.
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A catchment is an area where water is collected by thenatural landscape. In a catchment, all rain and run-offwater eventually flows to a creek, river, lake or ocean, orinto the groundwater system.
Natural and human systems such as rivers, bushland,farms, dams, homes, plants, animals and people can co-exist in a catchment. Healthy catchments provide:
a source of clean drinking water
unspoilt natural areas for recreation
habitat for plants and animals
healthy vegetation and waterways reliable and clean water for stock and irrigation, and
opportunities for sustainable agriculture and industry.
Our daily activities affect the health of our catchments.The first step to protect our catchments is to betterunderstand our impact on them.
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http://www.youtube.com/watch?v=w1Bmti7It-g -
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Darling 2,740 km (if include to Adelaide
and tributaries, otherwise 1,390 km)
Murray 2,530 km
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Australias Murray-Darling Basin
1.06 million sq. km
15% land mass
6.1% of Australias total run off
major river system
2 million people
2 capital citiesCanberra
Sydney
Brisbane
NEW SOUTH WALES
QUEENSLAND
VICTORIA
SOUTHAUSTRALIA
Melbourne
Swan Hill
MilduraMorgan
Menindee
MenindeLakes
LakeVictoria
Albury
Forbes
Dubbo
Moree
Charleville
Bourke
MurrayMurrumbidgie
Lachlan
Darling Macquarie
Border
Balonne
Barwon
Warrego
Adelaide
200 km
Murray Bridg e
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Clickview Video
Complete the questions
as we watch the video
http://www.clickview.com.au/LinkStart/?videoid=1218&videochapterid=5877 -
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The Murray-Darling Basin has been
termed Australia 's agricultural
heartland, its food basket'. It is
Australia's most important
agricultural region, accounting for
just over 34 per cent of the
nation's agricultural production in
2000/2001.The MDB dominates Australian
irrigated agriculture. The area of
irrigated agriculture in the Basin is
1.9 million hectares which is 75%
of the Australian total in
2000/2001.
Farms in the MDB cover an area of
88.6 million hectares, 19.4 per
cent of the Australian total farmarea of 455.7 million hectares. The
map of the Basin below has been
divided into different catchments.
The size of the pie chart (circle
graph) indicates the area of
agricultural land in the catchment
and the colours represent the type
of agriculture.
http://www.clickview.com.au/LinkStart/?videoid=6343 -
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Complete the following;
Activities 1- 6
Page 194-195 Take Notes
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http://www.murrayriver.com.au/about-the-murray/locks-weirs-dams-barrages/ -
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Dams are massive barriers built across rivers andstreams to confine and utilize the flow of waterfor human purposes such as irrigation andgeneration of hydroelectricity. This confinementof water creates lakes or reservoirs.
The first known dam was built in 2900 B.C.across the Nile River to protect the city ofMemphis from flooding. Dam build wascontinued into the time of the Roman empire,
after which dam construction was literally lostuntil the 1800s. Dams are a structure also seenin nature - beavers build dams to keep thewater deep enough to cover the openings totheir homes, protecting them from predators.
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Reasons to build a dam: generation of hydroelectricity
irrigation. These are often diversion dams, which stop a riversnatural course so that water can be sent off to a differentplace.
control flooding. These are called detention dams, which are
constructed to either stop or slow the amount of water in ariver.
According to Patrick McCully, campaigns director of theInternational Rivers Network, over 800,000 dams havebeen constructed worldwide for drinking water, floodcontrol, hydropower, irrigation, navigation, and water
storage. But since the 1950s, the peak of the big dam era,perceptions of dams and dam building have changed. Oncesymbols of development, dams today symbolize, as shownin this website, not progress but environmental and socialdevastation.
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is a barrier across a river designed to alter
the flow characteristics. In most cases, weirs
take the form of a barrier, smaller than most
conventional dams, across a river that causes
water to pool behind the structure (not
unlike a dam) and allows water to flow over
the top. Weirs are commonly used to alter
the flow regime of the river, prevent
flooding, measure discharge and help render
a river navigable.
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River Average Annual Flow(GL)
(approx)
Amazon (Sth America) 5,518,800
Yangtze (China) 1,014,700
Yenisey/ Selenga (Russia) 567,700
Ganga (India) 525,000
Mississippi/Missouri (USA) 405,100
Nile (Africa) 88,500
Hwang Ho (China) 51,100
Murray 14,700
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The single most detrimentalchange to the aquaticenvironment has been broughtabout by regulation of theriver.
Dams and weirs have altered
the volume of the rivers flow,the seasons in which it flows,and how often if floods.
River levels have changes, ashave water temperatures.
Artificial structures such as
locks and weirs from barrierswhich block the movement offish along the river, reducingthe success of breeding andfeeding.
http://www.youtube.com/watch?v=zcVfWOYeZ7Y -
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Salinity is the build-up of salt in soil and water.
It occurs naturally but in many parts of
Australia, human activities such as irrigation
have accelerated the process. Farms, irrigation
areas, wetlands, rivers, drinking water and
infrastructure are all affected.
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In general, the more material that is
suspended in water, the greater is thewater's turbidity and the lower its clarity.
Suspended material can be particles of clay,
silt, sand, algae, plankton, micro-organisms
and other substances.
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rainfall and catchment runoff catchment soil erosion
bed and bank erosion
bed disturbance, e.g. by introduced fish species suchas carp
waste discharge
stormwater
excessive algal growth
floodplain and wetland retention and deposition
flow waterway type
soil types
salinity.
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Water pollution fromriver regulation hasbrought about increasedlevels of turbidity fromassociated soil erosion.
This increases themurkiness of the waterand reduces the level oflight for plant growth.
This reduces the foodsource for herbivorousfish.
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Moreover, the problem of blue-green algae is of major concern.
Fertilisers, herbicides andpesticides add to the nutrientlevels in the water from surfacerunoff.
These nutrients allow algae toproliferate.
In 1991, the longest blue-greenalgae bloom in the world wasrecorded at the MDB, over a1,000 km stretch.
This reduces oxygen levels in thewater, leading to the death offish and reducing the light forother aquatic plants.
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Dry land Salinity
http://www.anra.gov.au/topics/salinity/pubs/national/salinity_salt
_aus.html
Great Resource
http://www.anra.gov.au/topics/water/pubs/estuary_assessment/e
st_ass_int_mddd.html
Resourcehttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchment
http://www2.mdbc.gov.au/subs/eResource_book/chapter4/p1.htm
http://www.waterwatch.org.au/publications/module4/turbidity.html
http://www.anra.gov.au/topics/salinity/pubs/national/salinity_salt_aus.htmlhttp://www.anra.gov.au/topics/salinity/pubs/national/salinity_salt_aus.htmlhttp://www.anra.gov.au/topics/water/pubs/estuary_assessment/est_ass_int_mddd.htmlhttp://www.anra.gov.au/topics/water/pubs/estuary_assessment/est_ass_int_mddd.htmlhttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www2.mdbc.gov.au/subs/eResource_book/chapter4/p1.htmhttp://www2.mdbc.gov.au/subs/eResource_book/chapter4/p1.htmhttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www.sca.nsw.gov.au/the-catchments/what-is-a-catchmenthttp://www.anra.gov.au/topics/water/pubs/estuary_assessment/est_ass_int_mddd.htmlhttp://www.anra.gov.au/topics/water/pubs/estuary_assessment/est_ass_int_mddd.htmlhttp://www.anra.gov.au/topics/salinity/pubs/national/salinity_salt_aus.htmlhttp://www.anra.gov.au/topics/salinity/pubs/national/salinity_salt_aus.html -
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