Water moves constantly between sea, air and land. Rivers shape the landscape as they flow from source to mouth.
🔄 The water cycle
The Sun’s heat causes evaporation from seas and lakes and transpiration from plants. Water vapour rises and condenses into clouds. Precipitation (rain, snow, hail) falls; water then runs off, infiltrates the soil or is stored as groundwater, and flows back to the sea. About 97% of the Earth’s water is salty; only about 3% is fresh, and most of that is frozen.
evaporation → condensation → precipitation
→ surface runoff / infiltration → river → sea
fresh water 3%; of that ~69% is ice
usable liquid fresh water < 1%
🖼️ See it
Near the source the river erodes downwards; near the mouth it flows slowly and deposits sediment.
🏞️ River processes and landforms
A river’s upper course is steep with V-shaped valleys and waterfalls; erosion is vertical. The middle course has meanders. In the lower course the river is wide and slow, with floodplains, levees and a delta at the mouth. Processes: erosion, transport and deposition. A drainage basin is the area drained by a river and its tributaries.
source → upper → middle → lower → mouth
upper: V-shaped valley, waterfall
middle: meanders
lower: floodplain, delta
flood risk is reduced by dams, levees, afforestation
Sediment is dropped where the river slows. That is why deltas form at the mouth.
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Evaporation
Evaporation is when liquid water:
Liquid → gas.
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Fresh water
Most of the Earth’s fresh water is:
Locked up.
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Meander
Meanders are most common in a river’s:
Bends.
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Delta
A delta forms where a river:
Mouth.
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The Earth has 97% salt water.
What percentage is fresh water?
Enter an exact answer, without rounding.
%
Subtract.
✍️ Type your answer · 6 of 7
A river 600 km long falls 1500 m from source to mouth.
What is the average gradient, in m per km?
Enter an exact answer, without rounding.
m/km
Divide drop by length.
✍️ Type your answer · 7 of 7
A river carries 2 million tonnes of sediment a year.
How many tonnes in 10 years, in millions?
Enter an exact answer, without rounding.
million t
Multiply.
📝 Lesson quiz · 5 questions
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Re-read the lesson, then give it another go.
Question 1 of 5
A tributary is:
Question 2 of 5
A V-shaped valley is typical of a river’s:
Question 3 of 5
Which process picks up and carries material?
Question 4 of 5
Afforestation reduces flood risk by:
Question 5 of 5
The drainage basin is:
Lesson 2 · Physical geography
🌊 Coasts
Where land meets sea, waves erode, transport and deposit material to create dramatic landforms.
🌊 Waves and erosion
Waves are formed by wind blowing over the sea. Constructive waves are low and deposit sand, building beaches. Destructive waves are high and erode. Erosion processes: hydraulic power, abrasion and attrition. Landforms of erosion: cliffs, wave-cut platforms, caves, arches and stacks.
Waves undercut the base of the cliff; it collapses and the cliff retreats, leaving a flat platform.
🏖️ Deposition and protection
Longshore drift moves sand along the coast in a zig-zag, forming spits and bars. Protecting coasts: hard engineering (sea walls, groynes, rock armour) is costly but effective; soft engineering (beach nourishment, dune planting, managed retreat) is cheaper and more natural. With sea levels rising, decisions about which coasts to defend are difficult.
groyne: wooden barrier that traps sand
sea wall: 1 km costs about £6 million
beach nourishment: 1 km costs about £1 million
sea wall for 5 km: 5 × 6 = £30 million
Defending everything is impossible. Planners weigh costs against the value of the land protected.
✏️ Quick check · 1 of 7
Constructive wave
A constructive wave:
Builds.
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Stack
A stack is a:
Detached rock.
✏️ Quick check · 3 of 7
Longshore drift
Longshore drift moves sediment:
Along.
✏️ Quick check · 4 of 7
Soft engineering
An example of soft engineering is:
Adding sand.
✍️ Type your answer · 5 of 7
A sea wall costs £6 million per km.
What does 5 km cost, in £ million?
Enter an exact answer, without rounding.
£ million
Multiply.
✍️ Type your answer · 6 of 7
A cliff erodes 2 m a year.
How many metres will it retreat in 25 years?
Enter an exact answer, without rounding.
m
Multiply.
✍️ Type your answer · 7 of 7
Beach nourishment costs £1 million per km, a sea wall £6 million per km.
How many times more expensive per km is the wall?
Enter an exact answer, without rounding.
Divide.
📝 Lesson quiz · 5 questions
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Re-read the lesson, then give it another go.
Question 1 of 5
Abrasion is erosion caused by:
Question 2 of 5
A spit is formed by:
Question 3 of 5
Which is hard engineering?
Question 4 of 5
Managed retreat means:
Question 5 of 5
Erosion rates on a coast are higher where:
Lesson 3 · Physical geography
🌡️ Climate Zones
Climate varies with latitude and geography. Climate graphs show temperature and rainfall through the year.
📊 Reading climate graphs
A climate graph combines a line for temperature (°C) with bars for rainfall (mm). The annual range is the difference between the warmest and coldest months, and total rainfall is the sum of the monthly bars. Equatorial climates have little temperature range; polar and continental climates have a large range.
warmest month 26 °C, coolest 10 °C
range = 26 − 10 = 16 °C
monthly rainfall: 60, 50, 40, 30, 20, 10 … (sum for the year)
🖼️ See it
Two places at the same latitude can have very different climates because of the other four factors.
🌎 Climate types
Broad zones: tropical (hot, wet, near the Equator), arid (dry deserts around 30° N and S), Mediterranean (hot dry summers, mild wet winters), temperate (mild, rain all year), continental (large seasonal range) and polar (cold all year). Monsoons reverse the wind direction seasonally and bring heavy summer rain to South Asia.
Mediterranean: Rome, Cape Town, Los Angeles
Monsoon: India — about 80% of rain falls from June to September
Deserts sit at about 30°. Dry air sinks there, producing high pressure and little rain.
✏️ Quick check · 1 of 7
Climate graph
On a climate graph, rainfall is usually shown by:
Columns.
✏️ Quick check · 2 of 7
Monsoon
A monsoon is a:
South Asia.
✏️ Quick check · 3 of 7
Mediterranean
A Mediterranean climate has:
Dry summers.
✏️ Quick check · 4 of 7
Deserts
Many deserts lie near:
Subtropical.
✍️ Type your answer · 5 of 7
The warmest month is 26 °C and the coolest is 10 °C.
What is the annual temperature range, in °C?
Enter an exact answer, without rounding.
°C
Subtract.
✍️ Type your answer · 6 of 7
Monthly rainfall for a year: 10, 10, 20, 30, 50, 80, 120, 130, 90, 40, 20, 10 mm.
What is the total annual rainfall, in mm?
Enter an exact answer, without rounding.
mm
Add them all.
✍️ Type your answer · 7 of 7
India receives about 80% of its 1200 mm of rainfall in the monsoon.
How many mm fall in the monsoon?
Enter an exact answer, without rounding.
mm
80% of 1200.
📝 Lesson quiz · 5 questions
0 / 5
Re-read the lesson, then give it another go.
Question 1 of 5
Which climate has the smallest annual temperature range?
Question 2 of 5
Tropical rainforests are found in a:
Question 3 of 5
A continental climate has:
Question 4 of 5
The polar climate has temperatures:
Question 5 of 5
A climate graph’s line shows:
Lesson 4 · Hazards
⚠️ Natural Hazards
Natural events become hazards when they threaten people. Understanding causes and responses saves lives.
🌋 Earthquakes and volcanoes
The Richter scale measures energy: each whole number is about 32 times more energy. The 2011 Tōhoku earthquake (magnitude 9.0) caused a tsunami. Volcanic hazards include lava, ash, pyroclastic flows and mudflows. Responses: prediction (monitoring gas and tremors), protection (earthquake-proof buildings), and preparation (drills, evacuation plans).
each +1 on the scale ≈ 10× larger waves, ≈ 32× more energy
magnitude 7 vs magnitude 5: 2 steps → about 32 × 32 = 1000× more energy
2011 Japan: about 18 000 killed
🖼️ See it
A hazard becomes a disaster when it meets vulnerable people. Warnings and preparation save lives.
🌀 Storms and floods
Tropical storms (hurricanes, typhoons, cyclones) form over warm oceans (above 27 °C) between 5° and 30° latitude and have winds above 119 km/h. The storm surge causes major flooding. The Saffir–Simpson scale rates hurricanes from 1 to 5. Poor countries suffer more deaths because of weaker buildings and warning systems, while rich countries suffer greater economic losses.
Hurricane Katrina 2005: about 1800 deaths, $125 billion damage
Cyclone Nargis 2008, Myanmar: about 138 000 deaths
Risk = hazard × vulnerability ÷ capacity to cope. The same hazard has very different outcomes in different places.
✏️ Quick check · 1 of 7
Tsunami
A tsunami is usually caused by:
Under the sea.
✏️ Quick check · 2 of 7
Storm formation
Tropical storms form over:
Warm water.
✏️ Quick check · 3 of 7
Preparation
An evacuation drill is an example of:
Be ready.
✏️ Quick check · 4 of 7
Vulnerability
Why do poorer countries often suffer more deaths?
Resources.
✍️ Type your answer · 5 of 7
Hurricane Katrina killed about 1800 people and the Tohoku disaster about 18 000.
How many times more deaths did Tohoku cause?
Enter an exact answer, without rounding.
Divide.
✍️ Type your answer · 6 of 7
A hurricane has winds of 120 km/h and moves at 15 km/h.
How many hours to move 150 km?
Enter an exact answer, without rounding.
hours
Distance ÷ speed.
✍️ Type your answer · 7 of 7
A flood causes £40 million damage across 5 towns equally.
What is the damage per town, in £ million?
Enter an exact answer, without rounding.
£ million
Divide.
📝 Lesson quiz · 5 questions
0 / 5
Re-read the lesson, then give it another go.
Question 1 of 5
A pyroclastic flow is:
Question 2 of 5
The Richter scale measures:
Question 3 of 5
A storm surge is:
Question 4 of 5
Which helps reduce earthquake damage?
Question 5 of 5
Prediction of volcanic eruptions uses:
Lesson 5 · Human geography
⚡ Resources & Sustainability
People depend on natural resources. Using them sustainably means meeting today’s needs without ruining the future.
⛏️ Renewable and non-renewable
Non-renewable resources (coal, oil, gas) take millions of years to form and will run out. Renewable resources (solar, wind, hydro, geothermal, biomass) are replaced naturally. Fossil fuels supply about 80% of world energy and release carbon dioxide. Renewable electricity is growing fast, with solar and wind now among the cheapest sources in many places.
world energy: ~80% fossil fuels, ~20% other
reserves ÷ annual use = years left
600 billion barrels ÷ 30 billion per year = 20 years
🖼️ See it
Sustainable use means meeting today’s needs without leaving too little for future generations.
♻️ Sustainable development
Sustainable development balances economic, social and environmental needs. Methods: reduce, reuse, recycle, efficient buildings, public transport, sustainable farming and fishing. The UN’s Sustainable Development Goals (2015) set 17 targets, including clean water, clean energy and responsible consumption. An ecological footprint measures how much land a person’s lifestyle needs.
17 SDGs, agreed in 2015, to be reached by 2030
2030 − 2015 = 15 years to deliver them
“Sustainable” means it can continue. A resource used faster than it renews is not sustainable.
✏️ Quick check · 1 of 7
Renewable
Which resource is renewable?
Not fossil.
✏️ Quick check · 2 of 7
Fossil fuels
Burning fossil fuels mainly releases:
A greenhouse gas.
✏️ Quick check · 3 of 7
Sustainable
Sustainable development means:
Think future.
✏️ Quick check · 4 of 7
Footprint
An ecological footprint measures:
Use of the planet.
✍️ Type your answer · 5 of 7
A country has 600 billion barrels of oil and uses 30 billion each year.
How many years will the reserves last?
Enter an exact answer, without rounding.
years
Divide.
✍️ Type your answer · 6 of 7
The UN has 17 goals; a class studies 3 per week.
How many weeks are needed to cover all 17? (round up)
Round your answer as the question asks.
weeks
Divide and round up.
✍️ Type your answer · 7 of 7
A household uses 4000 kWh a year; solar panels supply 25%.
How many kWh do the panels supply?
Enter an exact answer, without rounding.
kWh
25% of 4000.
📝 Lesson quiz · 5 questions
0 / 5
Re-read the lesson, then give it another go.
Question 1 of 5
Which is a non-renewable resource?
Question 2 of 5
Geothermal energy uses:
Question 3 of 5
Recycling helps by:
Question 4 of 5
Sustainable fishing means:
Question 5 of 5
SDGs stands for:
Final Challenge
🏆 10-Question Challenge Quiz
Questions from every topic in this course. Pick an answer for each one, then hit Check My Answers.
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💪 Keep practicing — go back through the lessons and retake the quiz!