The water cycle and sources of fresh water Cambridge IGCSE Environmental Management revision
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In plain words
The water in your glass has been rain, river, sea and cloud many times over. The amount of water on Earth never changes. It just moves between stores, and people can only use the small part that is fresh and within reach.
7 things to know
- Most of the Earth's water is salt water in the oceans. Only a small fraction is fresh, and most of that is frozen in ice sheets and glaciers. The other fresh water stores are ground water, lakes and rivers, and the atmosphere.
- Water moves between the stores by transfers. Evaporation: liquid water turns to water vapour. Transpiration: plants lose water vapour from their leaves. Condensation: water vapour cools and turns to droplets, forming clouds. Precipitation: water falls as rain, snow or hail.
- Interception: leaves and branches catch precipitation before it reaches the ground. Surface run-off: water flows over the ground. Infiltration: water soaks into the soil.
- Through-flow: water moves sideways through the soil. Ground water flow: water moves slowly through rock towards rivers and the sea.
- Sources of fresh water used by people. From the atmosphere: rain and snow. Surface water: rivers, lakes and reservoirs. Ground water: aquifers and wells. From the oceans: desalination plants, which remove the salt.
- An aquifer is a layer of permeable rock that holds ground water. A well is a hole dug or drilled down to reach it.
- There are five oceans: the Pacific, the Atlantic, the Indian, the Southern and the Arctic.
Worked example
Rain falls on a forest. Describe the routes it can take to reach a river.
- Some is intercepted by leaves, and drips to the ground or evaporates.
- Water reaching the ground may flow over the surface as surface run-off, the fastest route.
- Some infiltrates the soil and moves sideways as through-flow.
- Some goes deeper into the rock and reaches the river slowly as ground water flow.
Tips and tricks
- Evaporation is from surfaces such as the sea. Transpiration is from plants. Name the right one for the source in the question.
- Stores are where water is. Transfers are how it moves. A question asking for a transfer does not want "ocean".
It lands in your notebook with its questions as flashcards.
The water cycle and sources of fresh water: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
Where is most of the Earth's fresh water stored?
Most fresh water is frozen.
What is infiltration?
Water caught by leaves is interception.
Which transfer forms clouds?
Vapour cools and turns to tiny droplets.
Which is a ground water source?
An aquifer is water held in permeable rock.
Which of these is one of the five oceans?
Pacific, Atlantic, Indian, Southern and Arctic.
Which route takes rain to a river fastest?Stretch
Water over the surface meets the least resistance.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 7 marks. Write your answers on paper, then check them.
The water cycle and sources of fresh water
Cambridge IGCSE Environmental Management 0680 · 7 marks · papermunch.org
Name ______________________________ Date ______________
State the two largest stores of fresh water.[2]
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Ice sheets and glaciers, and ground water.
Describe three transfers that move water from the land surface or the sea into the atmosphere and back.[3]
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Evaporation: water turns to vapour from the sea and land. Condensation: the vapour cools and forms cloud droplets. Precipitation: water falls as rain or snow. (Transpiration from plants can replace evaporation.)
Describe what an aquifer is and how people take water from it.[2]
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A layer of permeable rock that holds ground water. People reach the water by digging or drilling a well.
Answers: The water cycle and sources of fresh water
- 1. Ice sheets and glaciers, and ground water.
- 2. Evaporation: water turns to vapour from the sea and land. Condensation: the vapour cools and forms cloud droplets. Precipitation: water falls as rain or snow. (Transpiration from plants can replace evaporation.)
- 3. A layer of permeable rock that holds ground water. People reach the water by digging or drilling a well.