The Murray-Darling Basin

7/28/2019 The Murray-Darling Basin

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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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The Murray-Darling Basin