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Water security

This resource is about the construction and purpose of all the infrastructure that has been built along the River Murray. It builds on earlier units in the Water as a resource theme, and develops understanding of how much water can be stored, and how much of it is used annually. This will lead students to a deeper understanding of the complexity of managing water for multiple purposes in a highly variable climate.


By the end of this resource, students will understand:

  • The quantity and variability of Australia’s water resources compared with other continents (ACHGK039)
  • The nature of water scarcity and ways of overcoming it, including studies drawn from Australia (ACHGK040)
  • The influence of environmental quality on the liveability of places (ACHASSK190)
  • Challenges to food production, including land and water degradation, shortage of fresh water, competing land uses, and climate change, for Australia and other areas of the world (ACHGK063)

How to use this resource

This resource draws on knowledge from the previous units in the Water as a Resource series. Although this Water Security topic can be done separately, students will gain a greater insight and depth of knowledge about why water security is such an issue in Australia by completing the sequence.


Ensure each student has access to:

*Hard copies can be ordered free-of-charge for education use by emailing with your postal address and the item/quantity required.

**The student worksheets have been designed so that those with laptops can complete and submit them digitally, saving paper.

Engage with the topic

Note. If this topic is being undertaken as a stand-alone piece of work (rather than following earlier units), students should first review the MDBA website information discover surface water.

Review: The southern part of the Murray–Darling Basin’s (MDB or ‘Basin’) river system is heavily drawn upon to supply the needs of people, industry and agriculture:

  • 2.6 million people living in the Basin (and about a million more outside) rely on it for household water.
  • $22 billion worth of food and fibre a year is grown using it – about 40% of Australia’s food.
  • Tourism in the Basin (much of it water-based) contributes $8 billion to regional economies.
  • Australia is the driest inhabited continent on earth yet Australians have the second highest average water use per person in the world – 493 litres a day.

Discuss: how do you think all these water needs are met in the ‘driest inhabited continent on earth’?

Activity 1

Divide students into pairs and ask them to investigate the Murray–Darling Basin Authority’s 'Timeline of river management' poster.

Things to ask students to think about and comment on:

  • What can you notice about the pattern of drought?
  • Did experiencing drought influence people’s settlement and development of farm land?
  • Notice what happened to Hume dam in 1968.
  • Why do you think no more dams have been built since 1979?
  • What’s your overall thoughts on what has happened to the way that water flows along the river over the past century?

Explore the topic

Activity 2

Pass out copies of the River Murray system poster (or view online).


To support all this, we have developed a lot of infrastructure to hold, control and deliver water.

  1. In fact, there are more than 3,000 structures on the Basin’s rivers (weirs, locks, channels, pipes as well as dams).
  2. Notice:
    • how dams are in upper reaches of rivers (higher valleys)
    • that irrigation areas are downstream of dams and larger weirs
    • that there are irrigation channels taking water further from the main rivers (this helps us grow food where we otherwise would not be able to).
  3. Ask – do you think that there is anything ‘natural’ about the way water now moves through the River Murray?
Activity 3

There are 4 sections to this exploration:

  1. Why and when infrastructure was built along the River Murray.
  2. What the infrastructure does.
  3. How much water can be stored.
  4. How much water is used by agriculture each year.

Note: Students could be divided into groups to research and report, or if more time is available all the investigations can be worked through by each group.

Pass out the student worksheets for the four different topics – see download links at top.

Students work through the 4 investigations and answer the corresponding questions on their worksheets.

Topic 1

Infrastructure development

Teaching notes Worksheet answers
Students dig deeper into the River management timeline.

This is about why and when infrastructure was built along the River Murray.

Students read the Student infrastructure history resource (see downloads) and view the video ‘A brief history of water use in the Murray–Darling Basin’. The soldier settlement scheme (see point 3 right) was introduced both to give ‘occupation’ to returning soldiers and also to provide a pool of people ‘willing’ to settle remote from the cities to expand agriculture (and economies). The student resource contains links to the National Museum of Australia with more information.

Re question 4: Higher river flow has changed from winter/spring (following natural rainfall cycle) to summer/autumn as water is stored then sent downriver from dams to support irrigation.

Re question 7: deeper knowledge may be demonstrated by answers ‘to supplement Hume dam’ or to ‘provide additional water for irrigation’. Question 11 is an assessment opportunity.

(If there is a less advanced group in the class, this is the more suitable activity for them.)

  1. Alfred Deakin, George and William Chaffey.
  2. Beat drought, grow more food, make land more productive or similar.
  3. Soldier settlement – after WW1 and 2 returning soldiers given cheap loans/land in small holdings pushing into western New South Wales and Victoria. Must make ‘improvements’.
  4. False – flow has changed from winter/spring (following natural rainfall cycle) to summer/autumn as water is sent downriver from dams to support irrigation.
  5. The barrages were built to prevent salt water entering the lower lakes and to guarantee that these lakes would always be fresh (as a drinking and stock supply for Adelaide).
  6. Murrumbidgee and Murray.
  7. Dartmouth was built to ‘drought proof the Murray’.
  8. 1 year.
  9. Hume was 1% full (of capacity 3,005 GL), so there was about 30 GL of water remaining.
  10. 6,200 GL / 500 = 13 Sydney harbours worth.
  11. Answer should demonstrate awareness that irrigation demand can always outstrip storage if there is insufficient rain for a few years.
Topic 2

What the infrastructure does

Teaching notes Worksheet answers
Students investigate a case study: the Goulburn–Murray Irrigation Area. The irrigation network on the Victorian side is managed by Goulburn–Murray Water and the New South Wales side by Murray Irrigation Ltd. The major infrastructure is managed (on behalf of the state governments) by the Murray–Darling Basin Authority.

Here students are identifying the extent of area in Victoria managed by Goulburn–Murray Irrigation that is fed by water from the dams, where each of the 7 districts’ water comes from, and the different types of infrastructure to get it where it is needed.

Ideally, the interactive map (bottom) should be used, however it requires Flash. If this is not available, the top (static) map can be downloaded and printed.

They also investigate the New South Wales side of the River Murray (where the infrastructure is managed by Murray Irrigation Ltd.).

Students should discover just how extensive the dams, weirs, channels and pipeline network is, how the water gets to farms, and that it is also used for hydropower generation.

Note. Correctly identifying where the water for Torrumbarry weir comes from is more difficult, and can show evidence of more advanced research skills. Question 5 is an assessment opportunity.

1. 68,000 sq. km. area, 70% of Victoria’s water storage, 7 river basins.

2a. Central Goulburn – Goulburn weir and Lake Eildon (primary)

2b. Murray Valley – Yarrawonga weir and Hume dam (primary)

2c. Torrumbarry weir (pumped via National Channel) and Hume Dam primary.

3. Dartmouth, Lake William Hovell, Yarrawonga and Eildon.

4a. 326,618 ML

4b. 556,913 ML

4c. 535,621 ML

4d.i. stock grazing pasture – lucerne/cereals (166,286 ML)

4d.ii. cereals for grain or seed – wheat, oats, maize (129,558 ML)

4d.iii. grapes (51,850 ML)

4d.iiii. pastures for hay – wheat, oats, maize (33,830 ML).

4e. stock grazing (evidenced by lots of annual crops, Lucerne, stock feed). Grazing is firstly dryland and secondly irrigated.

5. Students should demonstrate evidence of understanding of dams holding water for the primary purpose of supplying it to farmers, water delivery (by private companies) from the dam passing along rivers (generating hydropower in some cases) then into irrigation networks that get ever smaller ending up on farms. A higher level of understanding could show water being ordered, water moving seasonally (mostly spring-summer), evidence of understanding water-hungry crops or land-use, or the highly-regulated nature of water in this part of the Murray–Darling Basin.

Topic 3

How much water can be stored?

Teaching notes Worksheet answers
Students investigate the MDBA’s water in storages information and a historical flow and salinity report.

Give the students a printout of the Basin storage report for 22 April 2009.

Students need to understand the total storage capacity (22,256 gigalitres [GL]). Tell them that this is only for government-managed storages.

There is other water captured on farms and in private reservoirs, so the total storage capacity of the Basin is 23,162 GL* (if all the storages were full).

Discover that we can store all of the inflow most years.

*Bureau of Meteorology, 2016 National Water Account

Almost 3/4 of the total storage for the Basin is in the southern system (River Murray and tributaries).

Answers h. and i. are an assessment opportunity (for higher-level of understanding).

Activity 1

  1. 22,256 GL
  2. 16,294
  3. Dartmouth (3433 GL); Hume (3005 GL); Eildon (3334 GL). Hume and Dartmouth are in Upper Murray (New South Wales) and Eildon in Goulburn catchment (Victoria).
  4. Dartmouth 21%; Hume 2.1%; Eildon 12%.
  5. 3,807 GL.

Activity 2

  1. It is rarely ‘average’. Inflows are variable. It is quite likely to be ‘below average’, and we are likely to have much less than the average in storage.
  2. We can store all of it in most years (except exceptionally wet).
  3. Students should demonstrate understanding that an enormous amount of water can be captured in storages (44.5 Sydney harbours!), that current storages can already capture all the inflow in many years, and that unless it is unusually wet, we can use up most of the water that is stored in 1 year.
  4. Students should show understanding that an additional dam would only fill in exceptional years (or would likely ‘rob Peter to pay Paul’ – holding water that would otherwise have filled another storage, or being used as a resource by other farmers, towns or the environment).
Topic 4

How much water is used each year?

Teaching notes Worksheet answers
Students analyse Australian Bureau of Statistics data for the Murray–Darling Basin for 2016–17 and 2015–16

According to the ABS, water applied for irrigation in the MDB during the 2016–17 water year was 6,377,014 megalitres (6,377 GL). An additional 285,497 ML of water was taken from rivers and streams for agriculture (285.5 GL). In total 6,623 GL of water was used for agriculture in the Murray–Darling Basin.

The ‘all Australia’ usage was 9969 GL. Therefore 66% of all usage was in the MDB.

Total irrigation percentage (question b) = 6,377/9,104 = 70%

2016–17 was a very wet year, inflow was 14,800 GL.

2015–16 was, in contrast, very dry. Basin total inflows for 2015–16 were 3,040 GL.

In this year, total agricultural water use was 5,209.9 GL, and irrigation used 4,938.4 GL.

The amount of water allocated to farmers’ (and indeed the environments’) water ‘rights’ is a function of the amount in storage and rainfall. It is changed each year depending on conditions.

Answer 4 is an assessment opportunity.

    1. 67%
    2. 70%
    3. 43%
  1. 4,938.4 GL
  2. Students should demonstrate understanding that:
    • 2015 was a dry year
    • The storages were only about 20% full at the start
    • 5,560 GL (35%) more water was taken out than was ‘recharged’ from inflow
    • The year ended with less stored water than it started as a consequence.
  3. Graph example shown below. Students should demonstrate understanding that actual inflow is not well represented by ‘long-term averages’. We cannot count on ‘average flows’. Regardless irrigation needs a certain amount of water. In low inflow years, this can be significantly above ‘sustainable’ levels. The amount used does vary though. (This is because of the water allocation system – see left.)

Note. The representation of ‘% of records’ is for illustration only (not accurate).


By now students should understand that inflow is variable, water demands are high and relatively consistent (they are there every year) and we have done as much development of dams, weirs etc. as we can to store and deliver water, including being able to store more than we often get.

Explain that water security is a balancing act. The MDBA manages the River Murray’s operation – there is an operations centre that directs the movement of water, much like air traffic control. Operations are bound by many rules. Read more about running the River Murray.

To achieve the best possible outcome, computer models of various climate scenarios are done (with information coming from many sources like the Bureau of Meteorology). Combined with data about water in storages, how long it takes water to reach farms once it is released from dams, evaporation and seepage, and river height levels (from gauges) and more, river operators make decisions about when to move water from a higher storage (like Dartmouth) down to another one and from there when and how much to release. In addition, based on the rules, decisions are made about how much of water ‘entitlement’ holder’s allocation will be that year (i.e. 100%, 80%...). However, should very low inflows occur for many years, there will eventually be insufficient water in storages to meet demand. At other times, water releases are made to make more holding space in dams in the expectation of very high rainfall. In some cases, though thankfully rarely, floods may be so high that they cannot be captured in all the storages no matter how hard we try!

The operations priorities are therefore:

  • supplying critical human needs
  • meeting water orders
  • flood control – as most towns and farms are located close to rivers, we no longer accept the natural flooding cycle that would once have occurred after heavy rain.

Choose from the following activities (or complete them all to extend the unit of work).

Activity 4

View a couple of weekly operations reports. What are some of the considerations in running the rivers?

River Murray weekly reports

Activity 5

Print or project the River Operations decision activity.

Students can also research how Flood management is done at Hume dam.


Play Run the River. This app puts students in control of the river, they face real-world climate data and variability but must ensure all water users receive enough to get by.

If this is not feasible or time is short, play the Water sharing game. This demonstrates the same concept very quickly and easily.

Updated: 24 Nov 2021