Murray Darling Basin lesson

Challenges
facing the

Murray-Darling

River Basin

Year 9 Humanities

Term 3

1

Learning
Intentions

• To learn about the Murray

Darling Basin including facts,
background information and
value to the nation

• To understand the challenges

that face the Murray Darling
Basin ( environmental and
human) that impact on
agriculture and therefore, food security

3

The Murray–Darling Basin is the catchment for
Australia's largest river system. The Murray
and the Darling rivers are Australia's longest
rivers.

The Basin covers an area of more than 1
million square kilometers, which is equal to
14% of mainland Australia and is home to 2.6
million people. The Basin includes:
• 75% of New South Wales
• More than 50% of Victoria
• 15% of Queensland
• 8% of South Australia
• all of the Australian Capital Territory.

The Basin area is the 20th largest river catchment in the world.

Multiple Choice

The Murray Darrling Basin covers more than

• 10 million square km

• 100 square km

• 10 thousand square km

• 1 million square km

Multiple Select

Which states does the Murray-Darling basin go through?

• Western Australia

• Queensland

• South Australia

• Victoria

• New South Wales

Murray-Darling

Basin background

• Compared with other rivers of the world, the rivers of the Basin have carved winding courses across the landscape and are slow flowing, in areas that are very dry, hot and receive little rainfall, which leads to high evaporation rates . The Basin is one of the flattest catchments in the world.

• The Australian Constitution gives control of water resources to the states, but this makes it complex to administer because it involves cooperation between the four states.

• Since Europeans arrived in Australia, expanded settlements and agricultural activities have significantly affected the health of the river system.

Importance of the Murray-Darling River Basin

• The Murray-Darling River Basin is Australia’s ‘food bowl’.

• Agriculture (and associated industries) has helped create and continues to support important regional communities.

• One third of all food produced in Australia comes from the MDB and it generates 39% of national income.

• 52% of agricultural, industrial and domestic water used in Australia comes from the MDB (2005 data).

• The Basin produces $22 billion worth of food and fibre every year, feeding the nation and the world.

• Food security is dependent on the health of the basin.

Reorder

Reorder the following

• The Murray

• Darrling basin

• is Australia's

• 'food bowl'

1

2

3

4

• 1
• 2
• 3
• 4

Dropdown

The Murray Darling Basin supports the production of roughly one ​

Select answer

of our food and ​

Select answer

% of our income.

Australia's food security is dependent on the health of the basin.

​+

​=

Key challenges to
Murray-Darling Basin

In spite of the river system being
one of the major river systems of the world, the water flow is the lowest of all the world’s river
systems.

It receives only about six per cent
of Australia’s total rainfall, and over
94 per cent of the water that enters
the system is lost to evaporation.

Environmental challenges exist
even without agricultural activity, so
with agriculture , significantly more
pressure is put on an already fragile
ecosystem.

Water
quality

Salinity

Blue green
algae

Population

growth

Natural
climate

Different
states/
different
policies

Invasive
species

Erosion

Water flow

Precipitation

Multiple Select

Choose any which are key challenges for the Murray Darling basin

• evaporation

• money

• invasive species

• farming

Blue-green algae

.

Blue-green algae

Contaminates the surface
of leaves, fruit and vegetables, causing illness

Contaminated drinking water can cause illness in animals

Reduced productivity of crops

Crops grown to provide feed for livestock may cause illness

Multiple Choice

Blue-green algae contaminates the surface
of leaves, fruit and vegetables, causing ----

• price rises

• pests

• orange spots

• illness

Salinity

.

Less productive, waterlogged
soils where irrigation occurs
cause the water table to rise.

Loss of vegetation leads to increased erosion of stream banks

Surface runoff of salt leads to reduced water quality

An increasing area of non-productive land is due to the presence of surface salts

Hotspot

Where are the salts now that irrigation and land clearing has lifted them?

Multiple Select

How does land clearing effect salinity

• Means you need less water

• Means water rises in the water table

• Salts rise up to the surface

• Means less habitat for animals

Population growth

.

Population growth

Rapidly increasing population needs more food

Loss of farmland and quality fresh water are results of increased urban development.

Increased renewable energy demands increases demand for farmland for biofuels.

Increased land clearing results in loss of topsoil and nutrients

Match

Match the following

• Population growth

• Increased urban development

• More renewable energy

• More land clearing

Need more food

Less land for farming

Need more farms for biofuels

Loss of soil nutrients

• Need more food

• Less land for farming

• Need more farms for biofuels

• Loss of soil nutrients

Climate and precipitation levels

Australia is the driest inhabited continent on earth, and despite having one of the world’s largest catchments, river flows in the Murray–Darling Basin are among the lowest in the world.

Most of the Basin is arid or semi-arid, and rainfall varies greatly from year to year. In fact, the Basin has the most varied river flows of any similarly-sized river system in the world, with long droughts often broken by large rainfall events and floods.

Water inflows also vary greatly between the north and south. The sheer size of the Basin, coupled with a high evaporation rate, means that heavy rainfall in upland areas doesn’t always reach downstream areas. (94% of rainfall in the Basin is lost to evaporation.)

It is predicted that climate change will see extremes in weather becoming more common, and modelling suggests that the Basin will become hotter and drier, particularly in the south.

Multiple Select

Most of the Murray-Darling Basin is ___ or ____

• arid

• tropical

• temperate

• semi-arid

Water pollutants

Match

Match the activities and water pollutants they produce

• Agriculture

• Forestry

• Marine recreation

• Mining

• Urban runoff

fertilisers

sediment

fuel oils and rubbish

heavy metals andacids

chemicals and rubbish

• fertilisers

• sediment

• fuel oils and rubbish

• heavy metals andacids

• chemicals and rubbish

Water flow in the river system

Extraction of water for domestic use and irrigation is also a major activity that affects the flow of the rivers. 66% of all irrigated land in Australia is in the Murray-Darling Basin.

The Murray-Darling River system loses significant volumes of water
naturally, through evaporation and the absorption of water by wetlands and lakes. When vegetation covers the banks of the river, erosion is prevented and the river flows naturally.

When land is cleared, and the river banks are left bare, erosion deposits
silt into the river and this affects the flow of the river. Less and less water is available downstream.

The river flow has been affected so much that the
mouth of the river is closing and constant dredging is necessary to keep the river mouth open.

Labelling

Label the impacts on the river

Drag labels to their correct position on the image

pumping water out = less flow

silt = poor quality

evaporation = less downstream

River management

• In Australia, the states have full control over their own water resources.

• Because the Murray-Darling River system flows through four states and the ACT, each state controls that section of the river system that flows through it.

• By the time the Murray-Darling River system reaches its mouth in South Australia, it has been subjected to enormous pressure, as each state focuses on extracting the water it needs.

• Regular dredging is necessary now at the mouth because there is not enough flow
reaching the sea to keep the mouth open.

Salinity

Murray-Darling Basin

Issue in focus

Salinity

Salinity refers to the concentration
of salts in water or soil. While salt
is a natural feature of the
Murray-Darling Basin’s
landscapes and rivers, high
salinity can reduce crop yields,
affect aquatic ecosystems and
vegetation and damage
infrastructure.

Multiple Select

Salinity can effect

• crop yield

• infrastructure

• aquatic life

• air quality

Maintenance of natural environment

Retaining existing native vegetation
in good health is an essential first
step in managing recharge, as it is
easier to look after the plants that
are already in the ground and using water than it is to revegetate.

Preventing further loss of native
vegetation is a fundamental
requirement for managing salinity.

Reorder

Reorder the following

• preventing further loss

• of native vegetation

• is a fundamental

• requirement for

• managing salinity

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Maintenance of natural environment

Native vegetation plays an important role in the
diverse natural and social systems that abound in Australia.

Australia’s unique native vegetation evolved over millions of years and is well adapted to our soils and climate.

Native vegetation provides food, shelter and breeding habitat for native animals, prevents soil acidification and erosion, and keeps carbon out of the atmosphere where it would contribute to the Greenhouse Effect.

As we have seen, native vegetation can also manage recharge by using water where and when it falls.

Multiple Choice

Pick which does NOT relate to native Australian vegetation

• It is unique and has evolved over millions of years

• It provides food, shelter and habitat for native animal species

• It releases Greenhouse gasses, which contribute to global warming

• It uses the water in the water table and stabilises the soil