Year 7 Geography · AC9HG7K01 · AC9HG7K02 · AC9HG7K03 · AC9HG7K04
Too much, too little.
Katherine, in the Northern Territory, sits beside a river that floods in the wet season and keeps flowing through months with almost no rain in the dry. In March 2026 the Katherine River rose to 19.2 metres at the town’s bridge and flooded homes and the town centre. In the dry season the same river runs low and clear. In this lesson you will work out how that happens, and what the town can do about it.
1Meet the problem
How can Katherine have enough water in the dry season, and stay safe when the river floods?
Too much
From December to March, Katherine gets about four-fifths of its year’s rain. Days of heavy rain over the river’s catchment can push the river over its banks. Big floods hit the town in 1998, 2006 and 2026.
Too little
From May to September it hardly rains at all. The river keeps flowing because water seeps out of the limestone under the town. Farms, the town’s water supply and the hot springs all depend on that groundwater.
What we are learning
How water connects and changes places, where Australia’s water is, why people value it, and how communities and governments respond when there is too much of it or too little.
I can
- 1classify environmental resources, and explain when water is renewable.
- 2explain how water connects places as it moves through the environment.
- 3describe where Australia’s water and people are, and what that means.
- 4describe how different people value water, including First Nations Australians.
- 5explain the causes and impacts of a flood, and how communities and governments respond.
- 6propose a strategy for Katherine and explain its impacts.
Australian Curriculum v9, Year 7 Geography, Water in the world: AC9HG7K01 to AC9HG7K04, with the Year 7 inquiry and skills content descriptions AC9HG7S01 to AC9HG7S06.
Katherine water inquiry
Two pages: read Katherine’s rain and flood data, then plan a strategy for the town and weigh up its impacts on the environment, the economy and people. The same links are at the end of the lesson.
How this lesson works
- Meet the problem. Katherine has too much water in the wet season and depends on groundwater in the dry.
- Decide what you need to know. Choose the questions that will help, and write one of your own.
- Investigate. Five short investigations, each answering one of your questions.
- Propose a strategy. Choose what Katherine should do, and explain the impacts.
- Show what you know. Six questions.
Your answers and notes are saved in this browser, so you can stop and come back.
2What we need to know
What do we need to know?
A geographical inquiry starts with questions. Before you can solve Katherine’s problem, decide what you need to find out.
What we already know
- Katherine is on the Katherine River, about 300 km south of Darwin.
- More than 6,000 people live in the town.
- Most of the year’s rain falls from December to March.
- The river floods in some years. In March 2026 it peaked at 19.2 m at the bridge.
- In the dry season the river keeps flowing, even though it hardly rains.
Geographers ask
- What is it like?
- Where is it, and why is it there?
- How is it connected to other places?
- Why does it happen, and what impact does it have?
- Who values it, and how?
- What should be done?
Choose the questions that will help
0 of 6 useful questions chosenSix of these questions will help solve Katherine’s problem. Three will not. Tap the ones that will help. Each question you choose will be answered later in the lesson.
Our inquiry questions
Your chosen questions will appear here, in the order the lesson answers them.
Which of these is a geographical question about Katherine’s water?
My notebook
3Investigate · 1 of 5
Can water run out?
What kind of resource is water? Can it run out?
Geographers sort environmental resources into three groups by asking one question: will this resource be renewed, and how quickly?
Sort the resources
0 of 9 sorted correctlyChoose a group for each resource. Watch the last two closely: they are both groundwater.
A megalitre (ML) is a million litres. An Olympic swimming pool holds about 2.5 megalitres. On average, about 71,000 megalitres of rain soaks into the limestone around Katherine each year (NT Government).
Key idea
Water is a renewable resource because the water cycle renews it. Groundwater stays renewable only while it is refilled at least as fast as people pump it out.
That is why the amount of rain in each wet season matters so much at Katherine. Near Alice Springs, the deep groundwater is so old and so slowly refilled that pumping it is more like mining.When is groundwater a renewable resource?
My notebook
3Investigate · 2 of 5
Water on the move.
Where does the river’s water come from in the dry season, when it hardly rains?
Water does not stay in one place. It falls as rain, soaks into rock, flows underground and comes out again in springs and rivers. On the way it connects places, and it changes them.
Katherine’s rain, month by month
Tap a bar to read itAverage rainfall in each month at Katherine, in millimetres. Bureau of Meteorology, Katherine Aviation Museum weather station.
Tap or hover over a bar to read the rainfall for that month.
Show the numbers as a table
Use the chart. How many months get less than 10 mm of rain on average?
Under the ground at Katherine
Switch seasons, then follow the waterScroll sideways to see the whole diagram.
A diagram, not to scale. The cracks and caves are drawn far bigger than they really are, and the land is stretched upwards, so you can see where the water goes. At Katherine the aquifer is the Tindall Limestone: water is stored in its cracks and gaps, which range from less than a millimetre wide to the size of caves (NT Government).
One river joins places
From the headwaters to the sea- HeadwatersRain falls on the catchment.
- Nitmiluk GorgeThe river cuts through sandstone.
- KatherineSprings add groundwater from the limestone.
- Daly RiverThe Katherine River joins the Daly.
- Timor SeaWhere the water ends up.
Water dissolves rock
Rainwater is slightly acidic. Over a very long time it dissolves limestone, widening cracks and hollowing out caves. Cutta Cutta Caves, 30 km south of Katherine, are closed in the wet season because rain floods them.
Water carves landscapes
The Katherine River carved Nitmiluk Gorge through ancient sandstone. You can visit it in the Landforms and landscapes lesson.
Floods move mud and sand
Floodwater picks up mud and sand and drops them where it slows down: on the floodplain, and in flooded streets and homes.
Key idea
Water connects places as it moves: rain on the land becomes groundwater, groundwater feeds springs and rivers, and rivers carry water to the sea. In Katherine’s dry season, the river is kept flowing by groundwater from the limestone.
The top of the groundwater is the water table. Where it meets the riverbed, water seeps out through springs. Each wet season, recharge refills the rock.It is September, and it has hardly rained for four months. Why is the Katherine River still flowing?
My notebook
3Investigate · 3 of 5
Water and people.
Is Australia’s water found where most people live?
Katherine’s problem is part of a bigger pattern. Australia’s water is not spread evenly across the continent, and it is not always where the people are.
Northern Australia means all of the Northern Territory and the parts of Queensland and Western Australia that reach the Tropic of Capricorn. Runoff is rain that flows into creeks and rivers.
Where the rain falls, and where the people live
Tap a place on either mapAverage rain in a year
People in each capital city
- Northern Australia (shaded)
- Tropic of Capricorn
Show all the numbers as a table you can sort
Rain: Bureau of Meteorology climate statistics, average for each weather station’s years of record. People: Australian Bureau of Statistics, estimated population of each capital city area at 30 June 2025. Population is shown for capital cities only.
Which statement matches the two maps?
Three places, three strategies
Every place has to manage the water it has. These are three of the strategies Australian places use to manage the sustainability of their water.
Share the aquifer by plan
A water allocation plan sets how much water can be taken from the aquifer each year: up to 39,000 megalitres, and less in very dry years. Pumping close to the river is capped so the springs keep flowing.
Megalitres a year. On average, about 71,000 megalitres soaks into the aquifer each year. Water that is not taken stays in the rock and feeds the springs and the river.
Use old water carefully
The town’s water is pumped from bores at Roe Creek. The deep aquifers hold ancient water from a time when the climate was wetter, and they get very little new water today. Groundwater levels at Roe Creek are slowly falling. The water plan sets a limit for each groundwater resource.
Find new water
Since the mid-1970s, Perth’s rainfall has dropped by 15 to 20%, and the water flowing into its dams by 80%. Rain in the dams is now only 10 to 15% of Perth’s drinking water. Most comes from groundwater and from seawater turned into fresh water at desalination plants. People are still asked to save water.
Key idea
Australia’s water is unevenly spread. Most river water runs off in the north, where few people live, while most people live in the south-east and south-west.
So places manage the water they have: plans and limits on pumping, saving water, and new sources such as desalination.My notebook
3Investigate · 4 of 5
One river, many values.
Who uses and values the river, and in what ways?
People value water in different ways. Geographers sort these values into four kinds. One river can have all four at once.
Tag each card with its values
0 of 6 cards rightTap every value that fits, then check. Some cards show more than one value.
Jawoyn Country
Nitmiluk National Park is owned by the Jawoyn people and managed with the NT Parks and Wildlife Commission. The Jawoyn knowledge on this page is only what Jawoyn people have published themselves. To learn more, learn from Jawoyn people: at the Nitmiluk visitor centre, or through your school’s local First Nations contacts.
Key idea
Values can clash. Pumping more groundwater for farms has economic value, but less water would then reach the springs and pools that people swim in and that are sacred to Jawoyn people.
A good water plan has to balance these values. That is one reason Katherine’s plan protects the zone close to the river.Which of these shows a spiritual value of water?
My notebook
3Investigate · 5 of 5
When the river floods.
Why does the river flood, and what happens to people and places when it does?
A flood is a hydrological hazard: a natural event involving water that can harm people, places and environments. Big floods hit Katherine in 1998, 2006 and 2026.
Some people in your class may have been in one of these floods, or have family who were. Read and talk about them with care. If the flood stories are hard to read, tell your teacher.
Read the flood gauge
Tap a floodHighest height the river reached in each flood, at the river gauge at the Katherine bridge. The coloured lines are the Bureau of Meteorology’s flood levels for the town.
- Minor flood level
- Moderate
- Major
- Flood peak
- Approximate
- Minor flooding (16.0 m): low-lying areas next to the river are covered. Minor roads may close and low bridges go under.
- Moderate flooding (16.5 m): a bigger area is covered. Main roads may be affected, some buildings may flood above floor level, and some areas may need to be evacuated.
- Major flooding (17.5 m): large areas of town and country are covered. Many buildings may flood above floor level, towns can be cut off, major roads close, and services such as power may be cut.
What causes a flood like this?
Put the causes in orderImpacts and responses
0 of 11 sortedIs each card an impact of a flood, a response by the community, or a response by a government? The year says which flood it is from.
Key idea
Floods are caused by heavy rain over a whole catchment, not just rain on the town. They affect people, places and environments, and communities and governments respond before, during and after.
Before: warnings and levees. During: evacuation and rescue. After: relief payments and rebuilding. And the same rain that floods the town also refills the aquifer for the next dry season.Which of these is a long-term response to flooding?
My notebook
4Propose a strategy
Your strategy for Katherine.
What could Katherine do to have enough water, and to stay safer in floods?
Now use what you found out. Choose one strategy for the dry season and one for floods. Every strategy has trade-offs, so look at its impacts on the environment, the economy and people before you decide.
Choose and justify
There is no single right answerToo little: the dry season
Too much: floods
My strategy for Katherine
Compare with your first idea
My notebook
Key idea
A good strategy names who and what it helps, and is honest about who and what it costs.
Geographers judge strategies against environmental, economic and social factors. Katherine uses several strategies at once, because no single one solves both halves of the problem.5Show what you know
Show what you know.
Six questions, one for each “I can”. You get one try at each, so think before you tap.
Katherine’s groundwater is a renewable resource. What has to stay true for it to remain renewable?
What keeps the Katherine River flowing in the dry season?
Darwin averages 1,732 mm of rain a year and Adelaide 547 mm. Yet about nine times as many people live in Adelaide. What does this show?
Jawoyn people take drinking water from shallow water, not from the deep green pools where they say Bolung, the Rainbow Serpent, lives. Which value of water does this show most?
What caused the Katherine flood of January 1998?
Which sentence best explains the impacts of building a levee?
Katherine water inquiry
Two pages: read Katherine’s rain and flood data, then plan a strategy for the town and weigh up its impacts on the environment, the economy and people.
For teachers
Curriculum
Australian Curriculum: Humanities and Social Sciences, Geography, Version 9. Year 7, Knowledge and understanding, Water in the world.
AC9HG7K01: classification of environmental resources and the way that water connects and changes places as it moves through environments
AC9HG7K02: the location and distribution of water resources in Australia, their implications, and strategies to manage the sustainability of water
AC9HG7K03: the economic, cultural, spiritual and aesthetic value of water for people, including First Nations Australians
AC9HG7K04: the causes and impacts of an atmospheric or hydrological hazard, and responses from communities and governments
The inquiry runs through all six Year 7 skills content descriptions:
AC9HG7S01: develop questions for a geographical inquiry related to a phenomenon or challenge
AC9HG7S02: collect, organise and represent data and information from primary research methods, including fieldwork and secondary research materials, using geospatial technologies and digital tools as appropriate
AC9HG7S03: interpret and analyse geographical data and information to identify similarities and differences, explain patterns and trends, and infer relationships
AC9HG7S04: draw conclusions based on the analysis of the data and information
AC9HG7S05: identify a strategy for action in relation to environmental, economic, social or other factors, and explain potential impacts
AC9HG7S06: create descriptions, explanations and responses, using geographical knowledge and methods, concepts, terms and reference sources
From the Year 7 achievement standard:
By the end of Year 7, students describe how the characteristics of places are perceived and valued differently by people. They describe the importance of environments to people. They describe the features of a distribution. They explain the interconnections between people and places and environments, and describe how these interconnections change places or environments. Students describe a response or strategy to address a geographical phenomenon or challenge. Students develop questions about a geographical phenomenon or challenge. They collect, organise and represent relevant data and information, using primary research methods and secondary research materials. They identify similarities and differences, and describe patterns in data and information. They draw conclusions about the impact of the geographical phenomenon or challenge on people, places and environments. They develop a strategy for action. Students use geographical knowledge, concepts, terms and relevant findings from sources to create descriptions, explanations and responses.
All are quoted from ACARA’s Australian Curriculum Version 9.0. Where the lesson covers each one:
- AC9HG7K01: screen 3 (the resource sort, including groundwater that behaves as renewable at Katherine and close to non-renewable near Alice Springs) and screen 4 (the cut-away, the flow strip and three ways water changes places).
- AC9HG7K02: screen 5 (the rain and population maps, the northern Australia figures, and the Katherine, Alice Springs and Perth strategies).
- AC9HG7K03: screen 6 (six cards, two of them from material published by Jawoyn people, and values in conflict).
- AC9HG7K04: screen 7 (the 1998, 2006 and 2026 floods; the causes in order; impacts and community and government responses). The hazard studied is hydrological. Cyclone Les, which caused the 1998 flood, gives a way into atmospheric hazards if you want to extend.
- Skills: S01 on screen 2; S02 and S03 on screens 4, 5 and 7 (column chart, two thematic maps, a sortable table and the gauge chart); S04 through the checks and key ideas; S05 on screen 8; S06 in the notebooks and the strategy summary.
The seven geographical concepts all appear: place (Katherine), space (the distribution of water and people), environment (the limestone aquifer and the river), interconnection (rain, aquifer, river and sea; rain upstream and floods in town), sustainability (the allocation plan), scale (the town, the Northern Territory and Australia) and change (the seasons and the floods).
How the lesson is taught
The lesson is built as problem-based learning (Barrows and Tamblyn, 1980; Hmelo-Silver, 2004). It opens with a real, open-ended problem rather than content: Katherine has too much water in the wet season and depends on groundwater in the dry. Students decide what they need to know before anything is taught, investigate, then propose and justify a strategy. The screens supply the resources a facilitator would otherwise put together.
- Meet the problem (screen 1) and decide what you need to know (screen 2). Students choose six useful questions from nine and write one of their own. Each chosen question is answered on a later screen and shown at the top of it.
- Investigate (screens 3 to 7): resources, groundwater, distribution, values and the flood hazard.
- Propose (screen 8): five strategies for each half of the problem, each with its likely environmental, economic and social impacts and whether Katherine already uses it. There is no single correct choice. The justification is the assessable part, against AC9HG7S05 and the achievement standard’s “develop a strategy for action”.
- Show what you know (screen 9): one locked question for each success criterion.
Problem-based learning works best in groups of three or four, each keeping its own “need to know” list, with the teacher as facilitator rather than the source of answers. Allow four or five lessons: screens 1 and 2; 3 and 4; 5 and 6; 7; then 8 and 9 with the printable sheet.
Handle with care
- The March 2026 flood is recent. Students in the Northern Territory, and in Katherine especially, may have been evacuated, lost belongings or have family who did. Three people drowned in the 1998 flood. Avoid asking for personal stories, let students opt out of discussion, and check in before screen 7 with any students you know were affected. Involve your school’s wellbeing staff where needed.
- Jawoyn knowledge: the two Jawoyn cards use only what Jawoyn people have published through Nitmiluk Tours, which is part of the Jawoyn Association. The pictures show places, not people, beings or cultural designs. To go further, invite Jawoyn or other local First Nations community members, or contact the Nitmiluk visitor centre, following your school’s protocols.
Misconceptions the screens target
- Groundwater is an underground lake or river (screen 4). At Katherine it fills cracks, gaps and caves in limestone; the cut-away exaggerates them so they can be seen.
- Water is always renewable (screen 3). Only while it is refilled as fast as it is used: the deep aquifers near Alice Springs hold ancient water with very little modern recharge.
- Rivers are fed by rain all year (screen 4). Katherine averages less than 10 mm in each of five months; in the dry season the river is fed by groundwater.
- A flood comes from rain falling on the town (screen 7). Rain over the whole catchment, often far upstream, causes it.
- Levees stop floods (screens 7 and 8). They are built to a design size. Katherine’s are built for a flood expected about once in 20 years, and in 2026 the water overwhelmed the town-centre levee.
- More rain means more people (screen 5). The wettest parts of Australia have the fewest people.
About the data and the pictures
- Rain: Bureau of Meteorology climate statistics, average monthly and yearly rainfall over each station’s years of record: Katherine Aviation Museum (014903), Darwin Airport (014015), Alice Springs Airport (015590), Cairns Aero (031011), Brisbane Regional Office (040214), Sydney Observatory Hill (066062), Canberra Airport (070351), Melbourne Regional Office (086071), Hobart Ellerslie Road (094029), Adelaide Kent Town (023090) and Perth Airport (009021). Record lengths differ: Canberra Airport has 17 years, Sydney 159. The wet and dry season brackets on the chart follow the Bureau’s northern wet season of October to April.
- People: Australian Bureau of Statistics, Regional population 2024–25, estimated resident population of each Greater Capital City at 30 June 2025. Northern Australia: Department of Infrastructure (53% of the land, about 1.4 million people, 5.2% of the population; all of the NT and the parts of Queensland and Western Australia that intersect the Tropic of Capricorn). The maps shade the NT and the land north of the Tropic, which is close to that boundary but not exact. Runoff: CSIRO (2016), “more than half of Australia’s total surface water runoff”.
- Katherine’s aquifer: NT Government. Water is held in fractures and cavities of the Tindall Limestone from below a millimetre to cave size; the aquifer sustains the dry-season flow of the Katherine River and the Katherine Hot Springs; average recharge 71,000 ML a year; the 2026–2036 plan allows 39,000 ML a year in the shares shown; announced allocations cut extraction in very dry years; the discharge protection zone caps commercial use near the river at 13,816 ML a year. Most of Katherine’s drinking water comes from the river, with about ten per cent from bores (Power and Water).
- Alice Springs: NT Government (Alice Springs water allocation plan; State of the water resource 2024–25). Perth: Water Corporation (September 2025).
- Floods: 1998 from the Bureau of Meteorology’s report on Tropical Cyclone Les, the AIDR Knowledge Hub and the Katherine Times; the Bureau and AIDR record three drownings, and some later news reports say four. 2006: a peak just under 19 m on 6 April and a state of emergency; reporting in 2026 described the 2026 peak as just above the 2006 level, so the chart marks 2006 as approximate. 2026: SecureNT updates (7 March), the Katherine Times, AAP, and the Minister for Emergency Management (8 March 2026). Flood levels at the Katherine bridge (minor 16.0 m, moderate 16.5 m, major 17.5 m) are from the Bureau’s warning of 6 March 2026 as reported by the Katherine Times; the class descriptions follow the Bureau’s standard flood classifications. Levees: NT Government, Katherine flood mitigation, and the Katherine Times (29 October 2022).
- Values cards: Katherine Times (crops; about 20 to 25% of Australia’s mangoes), Nitmiluk Tours (tours; the Jawoyn name and Bolung), NT Government (hot springs; Aboriginal water reserve).
- The picture on screen 1 and the cut-away on screen 4 are illustrations, not maps of Katherine. Heights and depths are exaggerated.
Answers at a glance
- Inquiry questions (screen 2): useful, the six about resources, dry-season water, distribution, values, floods and what should be done; not useful, who Katherine was named after, the biggest fish, and Darwin’s population.
- Resource sort: continuous, sunlight and wind; renewable, trees, river water, barramundi and groundwater at Katherine; non-renewable, gold, coal and the deep groundwater near Alice Springs (choosing renewable for it gets “close”, with the reason).
- Rain chart: five months under 10 mm, May to September.
- Values: farms, economic; tours, economic (aesthetic and cultural also accepted); hot springs, aesthetic (economic accepted); the name Nitmiluk, cultural (spiritual accepted); Bolung, spiritual (cultural accepted); Aboriginal water reserve, economic (cultural accepted).
- Gauge: 19.2 m minus 17.5 m is 1.7 m.
- Causes in order: heavy rain over the catchment; soaked ground, so the rain runs off; creeks carry it to the river upstream; the river rises past the major flood level; water spreads over low ground in town.
- Impacts: 1,100 homes and the town centre (1998), Darwin cut off (1998), three drownings (1998), hospital, schools and drinking water (2026). Community responses: families to evacuation centres, the pharmacy staff. Government responses: flood warnings, the patient flights, relief payments, the levee, NT Emergency Service sandbags.
- Checks: q-ask, why the river keeps flowing; q-res, refilled as fast as it is pumped; q-rain, five; q-conn, groundwater through springs and the riverbed; q-pat, wettest in the north, people in the south-east; q-val, the deep pool; q-flood, levees and planning.
- Exit check: x1 less pumped out than soaks in; x2 groundwater; x3 water is not where most people live; x4 spiritual; x5 rain from the remains of Cyclone Les; x6 protects in smaller floods, costs millions, a bigger flood can still get in.
Saved progress
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References
- Barrows, H. S., & Tamblyn, R. M. (1980). Problem-based learning: An approach to medical education. Springer.
- Hmelo-Silver, C. E. (2004). Problem-based learning: What and how do students learn? Educational Psychology Review, 16(3), 235–266.
Sources
- ACARA: Australian Curriculum Version 9, Geography, Year 7
- Bureau of Meteorology: Climate statistics, Katherine Aviation Museum (and the other ten stations listed above)
- Bureau of Meteorology: Northern wet season summary, October 2023 to April 2024
- Bureau of Meteorology: Tropical Cyclone Les
- Bureau of Meteorology: Flood warning system brochure, with the standard flood classifications
- AIDR Knowledge Hub: Flood, Katherine, Northern Territory, January 1998
- Katherine Times: Katherine’s worst natural disaster
- Katherine Times (6 March 2026): Major flood warning issued and Katherine River peaks at 19.2 m
- Katherine Times (20 March 2026): Pharmacy staff brave floodwaters
- AAP via Farm Online (8 March 2026): Katherine River’s 19.2 m peak
- SecureNT: Update 3, Flooding Katherine and Beswick (7 March 2026)
- Minister for Emergency Management (8 March 2026): Disaster assistance activated for flood-affected residents of Katherine
- NT Government: Katherine flood mitigation and Katherine Times (29 October 2022): the $10 million levee
- NT Government: Tindall Limestone Aquifer, Katherine, background brief
- NT Government: State of the water resource, Katherine 2024–25
- NT Government: Managing water in and around Katherine, FAQ and Katherine water allocation plan 2026–2036 declared
- Power and Water: Katherine water supply
- NT Government: Alice Springs water allocation plan and State of the water resource, Alice Springs 2024–25
- Water Corporation (September 2025): Wet winter belies true impact of declining streamflow to Perth dams
- Department of Infrastructure: Northern Australia and CSIRO (2016): Water options for northern Australia
- Australian Bureau of Statistics: Regional population, 2024–25
- Nitmiluk Tours: About the Jawoyn and Nitmiluk National Park
- NT Government: Cutta Cutta Caves Nature Park
- Katherine Times: Katherine food bowl
- UNSW Connected Waters: Great Artesian Basin groundwater age