Transcript RGM Land and Water Mgt

Issues in Australian Environments
Land and Water Management
Case Study: Murray Darling River
Traditional landuse
• http://dl.screenaustralia.gov.au/module/19/ 2 min video 1966
Nomads in the Gibson Desert
River fish traps like these near Brewarrina,
New South Wales, were built using a complex
network of rock walls designed to channel fish
of varying sizes into specific catchment areas.
Aboriginal Land use
• Aboriginal Australians have occupied the
Murray-Darling river system for many
thousands of years, and Europeans for less
than 200. The Aborigines lived in harmony
with the land and the river’s cycles of flood
and drought. The river provided them with
fish and crustaceans, and other foods; the
river red gums provided the bark for their
canoes and for shelter. They built elaborate
fish traps and made nets for catching fish
and birds.
Aboriginal Land use
• Aboriginal communities along the
Murray River were denser than almost
anywhere else on the Australian
mainland, because of the relatively
continual availability of food and water.
European Settlers
Land clearing
• When the British arrived in 1788 10% of
Australia was covered by forest.
• Woodlands covered a further 23 %. Within
200 years the area covered by eucalypt
forest has been halved and the area of
rainforest has been reduced by 75 %.
• The forests that remain are disappearing at
the rate of 1 % per year.
• In particular the rate of deforestation is
highest in SE QLD and exceeds that being
carried out in the Amazon.
Cultivation of crops
• Experimental rain grown cotton crops
were first trialled in Queensland in the
mid 1800s and production slowly
increased until the 1930s when world
prices fell enough for production to
cease. In the 1950s and 1960s irrigated
cotton production began and by the
1970s commercial production of
irrigated cotton accelerated rapidly.
Wheat
• Wheat is the major crop in the MDB
(Murray Darling Basin).
Cotton
• Today, cotton is mainly grown in the
Northern part of the Murray-Darling
Basin, along the Darling River and near
the tributaries in northern New South
Wales and southern Queensland. About
80 per cent of cotton crops are grown
under irrigation. The Murray-Darling
Basin accounts for over 93 per cent of
Australia’s raw cotton production
•
http://www.smh.com.au/news/water-issues/cotton-sucking-life-out-ofmurray/2008/08/15/1218307227802.html August 2008
Rice
• Most of Australia’s rice is also grown within
the Murray-Darling Basin. In 1924 rice
production began around the townships of
Leeton and Griffith in the Murrumbidgee
Irrigation Area. Rice is now the major
irrigated cereal crop and is grown entirely in
the Murrumbidgee and Murray valleys of New
South Wales. The annual rice production in
Australia is between 1 and 1.7 million tonnes,
with 1.2 million tonnes produced in 2002. Rice
requires more water to grow than cotton.
Vineyards, Citrus, Fruit and Nut orchards
• Today, vineyards, citrus, fruit and nut
orchards cover approximately 30,000
hectares of irrigated land and produce
one third of Australia’s wines and citrus
fruit. Up to 90 per cent of South
Australia’s citrus, stone fruits and nuts
are produced in the area. Angas Park,
Australia’s largest producer of dried
tree fruit, has a plant in Loxton
employing a large team of full-time and
seasonal workers.
Vineyards
• The Riverland has also become the
largest wine-producing region in
Australia and most major Australian
wine companies source grapes from the
area. The National Wine Centre of
Australia provides more information
about Riverland wineries.
Land degradation: What is it?
• Land degradation is any change in the
land that reduces its existing or
potential productivity.
Land degradation
• Our soil resources are an important natural asset, and
their degradation is a significant concern to
Australian farmers, governments and the general
public. When left untreated, degraded soil reduces
agricultural productivity, while salinity can damage
buildings and infrastructure such as water pipes,
roads and sewers. Degradation can also damage
habitat for wildlife, kill micro-organisms that live in
the soil, and harm the quality of our inland waters.
Causes
Land clearing
Irrigation
Video
• http://www.powerhousemuseum.com/ed
ucation/ecologic/aussalt.htm Why is
Aust So Salty video. Need to open it in
broadband 6 mins
Salinity
Where is it and why?
Soil Salinity
• Salinity occurs when the water table
rises, bringing natural salts to the
surface (in sufficient quantity, these
salts are toxic to most plants). When
trees or other deep-rooted vegetation
are replaced with vegetation that uses
less water, the water table may rise to
cause dryland salinity. (If the water
table rises through increased irrigation
then irrigation salinity can occur.
Dryland Salinity
• Dryland Salinity is where the water
table rises after more water infiltrates
due to the clearing of trees.
Recharge and leakage
• Water `leakgage' beneath the root zone and entering
internal drainage and groundwater systems has
increased.
• Ground water recharge is the amount of water being
added to the ground water. If this is higher than
discharge, which is the amount of water lost from the
ground water, then the water table rises. As it does,
the water dissolves salt held in the soil profile, and
the salt becomes more and more concentrated as the
water moves upwards. If the salty water keeps rising,
it eventually reaches the surface and subsurface
layers of the soil. The water evaporates, leaving the
salt behind.
Dryland salinity in WA
Irrigation Salinity
• Irrigation Salinity is where the water
table rises due to excessive irrigation
meaning extra water infiltrates.
• Concentrated salt at the surface will kill
vegetation.
• Also plants trying to survive in saline
areas are preferentially grazed.
• Removing vegetation causes problems
with wind and water erosion and lost
production.
Salinity Forecasts
State/Territory
New South Wales
Victoria
South Australia
Western Australia
Tasmania
Queensland
Total
2000
181 0001
670 0003
390 000
4 363 000
54 000
not assessed
2050
300 000
1 100 000
600 000
8 800 000
90 000
3 100 000
17 000 000
http://www.abc.net.au/water/stories/s15
72428.htm Water facts on Salinity
Degradation
• Our soil resources are an important natural
asset, and their degradation is a significant
concern to Australian farmers, governments
and the general public. When left untreated,
degraded soil reduces agricultural
productivity, while salinity can damage
buildings and infrastructure such as water
pipes, roads and sewers. Degradation can also
damage habitat for wildlife, kill microorganisms that live in the soil, and harm the
quality of our inland waters.
Murray Darling
• Show Clickview 16 min video River’s End
60 mins 2008
• And clickview 507 Catalyst 2008.05.01
• http://www.abc.net.au/water/stories/s
2003556.htm
Murray Darling
• is the 7th biggest river system on the planet
• is Australia's largest and most developed river
system
• covers more than 1 million square kilometres of land
• provides drinking water for over 3 million people
• encompasses 30,000 wetlands
• represents much of Australia's unique flora and fauna
• provides over 41% of Australia's gross value of
agricultural production
• once boasted 28 billion trees, yet now has only 5
billion
Murray Darling Basin Stats
• http://www.abs.gov.au/ausstats/[email protected]
sf/mf/4610.0.55.007
Individual responses responses to salinity
• In southern Australia key responses
include improving the water balance
(through farming techniques or
revegetation), draining or intercepting
and evaporating salty groundwater, or
living with salinity and implementing
saline agriculture and aquaculture.
• Different strategies suit different
regions because salinity control
invariably involves trade-offs between
social, financial and environmental goals.
Management
• Options for recharge management
• Recharge reduction options include
changing land use and farming practices,
intercepting fresh water using
engineering methods; retaining, reestablishing and managing remnant
native vegetation, or a combination of
these.
Engineering methods
• Engineering methods that intercept
surface water through banks or shallow
drains are used for recharge control.
Good quality water harvested by
pumping or water diversion can be
reused elsewhere on a property for
irrigation or stock watering, by making
productive use of water that may
otherwise be a problem once it
intercepts salt in the landscape.
Protection of remnant native
vegetation
• Management and protection of remnant
native vegetation is the first step in
working towards a higher water-using
landscape.
• Native vegetation over a substantial
part of a catchment provides optimum
recharge control as most salinisation is
the consequence of water balance
change that followed tree clearing.
A revolution in land use and
farming systems including:
• phase farming (alternating phases of
crops and lucerne);
Individual responses
• Strips farming following the contour
to combat water erosion on a slope.
Group response to the issue
• http://landcaresa.org.au/murray/initiati
ve/index.html Landcare
Group responses
• http://landcaresa.org.au/murray/initiati
ve/index.html Landcare website