GAB & MD Worksheet
Using http://www.derm.qld.gov.au/water/gab/ and Chapter 8 Geo Focus 2 (link on
studyismybuddy.com) complete the following activities:
Part 1 MD – Murray Darling
1
Which states and territories lie within the Murray–Darling Basin?
a. It covers about 1 million square kilometres. Extending from Roma
in Queensland to Goolwa in South Australia, the Murray–Darling
Basin drains three-quarters of New South Wales and half of
Victoria.
2
Outline the importance of the Murray–Darling Basin.
a. The Murray–Darling Basin is the catchment area for Australia’s
largest river system, making up about 14 per cent of Australia’s
land mass. It contains 20 major rivers and is important for much of
Australia’s agricultural production
b. It supports human economic activity including dryland and
irrigated agriculture, mining, fisheries, forestry, recreation and
tourism.
c. Contributes around 40 per cent of Australia’s total agricultural
output per year.
d. Contains 70 per cent of Australia’s irrigated farmland.
e. It supplies the drinking and domestic water for two million people.
f. It provides important habitats for biodiversity, including more
than 30 000 wetlands, such as the Macquarie Marshes in northwestern New South Wales and the Coorong at the mouth in South
Australia.
3
What are the five main human impacts on the Murray–Darling system?
a. the allocation of water for irrigation,
b. disruption of normal river flows through the building of dams and
weirs,
c. land clearing,
d. fertiliser and chemical use, and
e. the introduction of foreign species of plants and animals
4
What is water over-allocation? Why is it unsustainable?
a. In the past there was more allocation of water to farmers on
paper than there was flowing in the river. This is called overallocation and it is unsustainable
5
Why do algal blooms occur?
a. Nutrients from fertilisers used on crops can be washed into
waterways. These fertilisers encourage plant and algal growth.
Combined with reduced river flows and slow moving or stagnant
oober Pedy. With an area of
metres the basin underlies
he Australian continent. (See
clayey sands were laid down by floodplains and lakes.
This process produced a profile of alternating layers.
As rivers eroded the steeper slopes, the land began to
flatten, and deposition in lakes and large floodplains
ume of water that is estimated
became more dominant. The sandy sediments
water,
algal blooms
can
form, which
are
poisonous to humans,
tres. It is enough water to fill
consolidated
to form the
permeable
sandstone
from
mes.
which
the
artesian
water
is
now
tapped
and
the
clayey
animals and fish.
sediments became the impermeable layers. Thickness of
6
Why isthe
cooperation
onvaries
salinity
combined layers
from necessary
less than 100between
metres on all the levels of
the basinacross
extremities
over 3000
metres in the deeper
government
thetowhole
Murray–Darling
Basin?
parts. (See Figure 2).
a. In order to resolve disputes and to manage the catchment
During theeffectively,
Cretaceous period
(about 100 million
years
resources
as differing
agricultural
and environmental
ago), down warping and high sea levels created a
interests
areover
prevalant
shallow sea
much of inland Australia. This sea
deposited mainly muddy sediments, which later
consolidated, forming the rolling downs that can be seen
Part 2 – GAB – Great
today.Artesian Basin
1
2
3
How much
water does the GAB contain?
As the Cretaceous period ended, about 65 million years
a. 64 900
million
megalitres
ago, uplift
ended
sedimentation in the region of the GAB.
Further
uplifting
and
erosion resulted in the exposure of
How old is it?
the permeable sandstones in the marginal areas of the
a. About
million
years
ago
Basin.65
This
occurred
mainly
along the western edge of
the
present
day
Great
Dividing
Rainfall began to
Use diagram to illustrate whyRange.
it flows
infiltrate into the sandstones that led to the accumulation
of the vast groundwater reserve.
asin
med
s, the GAB was created by the
at eventually formed
able sandstone and
d mudstones. The deposits
pressions; the Carpentaria,
s which together form the
Figure 2—Generalised cross-section of the Great Artesian Basin
Artesian water
Artesian water is underground water confined and
pressurised within a porous and permeable geological
formation. Formations that store and transmit water are
referred to as aquifers. When one of these aquifers is
tapped by a bore, artesian water may flow naturally to the
surface.
The Great Artesian Basin
4
The Great Artesian Basin (GAB) is one of the largest
At the end of the Triassic period
artesian groundwater basins in the world. It extends
these basins occurred and erosi
2400 kilometres (km) from Cape York in the north to
sedimentation. Throughout the p
Where Dubbo
does it
flow?
in the
south. At its widest it is 1800 km from the
was deposited by streams and r
Darling Downs
west of Coober
Pedy.
WithCape
an area
of in the
clayey
sands
a. It extends
2400tokilometres
(km)
from
York
north
towere laid down by
over 1.7 million square kilometres the basin underlies
This process produced a profile
Dubbo in the south. At its widest it is 1800 km from the Darling
approximately one-fifth of the Australian continent. (See
rivers
eroded the steeper slo
Downs
to1).west of Coober Pedy. With an area of overAs1.7
million
Figure
flatten, and deposition in lakes a
square
kilometres
the volume
basin underlies
one-fifth
ofdominant. The sa
The GAB
stores a huge
of water that approximately
is estimated
became more
be 64 900 million
megalitres. It is enough water to fill
consolidated to form the permea
the to
Australian
continent
Sydney Harbour 130 000 times.
which the artesian water is now
sediments became the imperme
the combined layers varies from
the basin extremities to over 300
parts. (See Figure 2).
During the Cretaceous period (a
ago), down warping and high se
shallow sea over much of inland
deposited mainly muddy sedime
consolidated, forming the rolling
today.
As the Cretaceous period ended
ago, uplift ended sedimentation
Further uplifting and erosion res
the permeable sandstones in the
Basin. This occurred mainly alon
the present day Great Dividing R
infiltrate into the sandstones tha
of the vast groundwater reserve.
Figure 1—The Great Artesian Basin
How the basin was formed
5
many managed?
millions of years, the GAB was created by the
How is Over
it being
Figure 2—Generalised cross-section
deposition of sediments that eventually formed
a. A collaborative
strategic
management
plan is used by
alternating layers15ofyear
permeable
sandstone
and
Artesian water
Queensland,
South
South
Australia, Northern
impermeableNew
siltstones
and Wales,
mudstones.
The deposits
Artesian water is underground w
occurredand
in three
depressions; thegovernments
Carpentaria,
Territory
themajor
Commonwealth
to achieve
pressurised within a porous and
Eromanga and Surat basins which together form the
sustainability
of the basin and its resources. The Great
Artesian
formation.
Formations that store
GAB.
referred
to
Basin Coordinating Committee (GABCC) is responsible for as aquifers. When on
tapped by a bore, artesian water
coordinating management of the GAB between the jurisdictions
surface.
involved.
Part 3 - General
http://www.anbg.gov.au/aust-veg/seasonal-rainfall.html
 Australias seasons are:



Summer: December to February

Autumn: March to May

Winter: June to August
Spring: September to November
Wet: December to March


Dry: April to November
1. Find maps that show Australia’s average annual rainfall and summer and
winter rainfall patterns.
http://www.bom.gov.au/jsp/ncc/climate_averages/rainfall/index.jsp
2. What parts of Australia receive the highest amounts of rainfall?
Broome
3. What parts of Australia receive the least rainfall?
http://www.bom.gov.au/jsp/ncc/climate_averages/raindays/index.jsp
4. Describe and explain the pattern of Australia’s summer rainfall.
It is region dependent - In the north there are tropical regions with high
temperatures and high humidity and distinct wet and dry seasons. In the
centre of the country are dry, desert regions with high daytime
temperatures and low amounts of rain. In the south are the temperate
regions with moderate rainfall and temperatures ranging from hot to cold.
The tropical regions of Australia are in the north of the country. They
include the central and northern parts of the Northern Territory and
Queensland, and the northern parts of Western Australia. The weather in
the Australian tropics has two very different seasons: the wet season and
the dry season.
The wet season lasts about six months in summer and spring, between
December and March. It is hotter than the dry season, with temperatures
between 30 and 50 degrees Celsius. This is because of the high humidity
during the wet, which is caused by large amounts of water in the air.
During the wet there is a lot of rain, which frequently causes flooding.
The dry season lasts about six months in autumn and winter, usually
between May and October. Temperatures are lower and the skies are
generally clearer during the dry. The average temperature is around 20
degrees Celsius.
http://australia.gov.au/about-australia/australian-story/austn-weather-andthe-seasons
5. Describe the pattern of Australia’s winter rainfall.
Region dependent – the temperate areas receive more rain during the winter
periods and the tropical regions receive the majority of their rain during the
rainy season
6. What parts of Australia receive winter and summer dominant rainfall?
Winter = temperate / dry
Summer = tropical