Chapter 16 – Water: a precious resource

These NCERT Class 7 Science Chapter 16 notes explain why water is one of the most precious natural resources on Earth. The chapter helps students understand that although water is abundant, usable fresh water is very limited.

Water: A Precious Resource explains sources of fresh water, the water cycle, groundwater, and the concept of water table. It also highlights problems like water scarcity and the need for proper water management and conservation.

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1. Introduction: why water is precious

•  Water is essential for all living beings, and life is impossible without it.
•  Although Earth looks water-rich, usable fresh water is very limited.
•  Drinkable water is scarce despite wide availability of water.

2. Availability of water on Earth

•  About 97% of Earth’s water is salty in seas and oceans.
•  Only 3% is fresh water, and most of it is locked in glaciers and ice caps.
•  Very little fresh water is available for human use.

3. Sources of fresh water

•  Rivers, lakes, ponds, wells, springs, and rainwater are sources.
•  Rain is the main source of fresh water on Earth.

4. Forms of water

•  Water exists as solid (ice), liquid (water), and gas (water vapour).
•  Change in temperature causes change of form.

5. Water cycle

•  The water cycle is the continuous movement of water on Earth.
•  It includes evaporation, condensation, and precipitation.
•  Water rises as vapour and returns as rain.

6. Groundwater

•  Groundwater is water stored below the ground surface.
•  It is obtained through wells, handpumps, and tube wells.

7. Water table

•  The water table is the level below which soil is fully saturated with water.
•  It changes due to seasons and human use.

8. Depletion of water table

•  Population growth, urbanisation, and industrial use increase water use.
•  Deforestation and less rainfall reduce groundwater recharge.

9. Effects of water scarcity

•  Causes shortage of drinking water and crop failure.
•  Leads to health problems and migration of people.

10. Distribution of water in India

•  Rainfall is uneven across regions.
•  Rajasthan faces water scarcity, while Assam faces floods.

11. Water management

•  Water management means planned and careful use of water resources.
•  It is essential to prevent a water crisis.

12. Rainwater harvesting

•  Rainwater harvesting means collecting and storing rainwater.
•  Methods include rooftop harvesting, check dams, and percolation pits.
•  It recharges groundwater, reduces scarcity, and is eco-friendly.

13. Role of forests in water conservation

•  Trees increase groundwater recharge and reduce runoff.
•  Forests help prevent floods and droughts.

14. Conservation of water

•  Turn off taps, repair leaks, and use buckets instead of showers.
•  Reuse water wherever possible to save resources.

15. Drought

•  Drought is a long period of very low rainfall.
•  It causes severe water shortage.

16. Flood

•  Floods occur due to heavy rainfall and excess water.
•  They cause damage to life and property.

17. Importance of water conservation

•  Ensures water for future generations.
•  Maintains ecological balance.
•  Supports agriculture and industry.

18. Important keywords with simple definitions

•  Water cycle – continuous movement of water on Earth.
•  Evaporation – change of water into vapour.
•  Condensation – change of vapour into water droplets.
•  Precipitation – falling of rain, snow, or hail.
•  Groundwater – water stored below the Earth’s surface.
•  Water table – upper level of groundwater.
•  Rainwater harvesting – collection and storage of rainwater.

Understanding NCERT Class 7 Science Chapter 16 – Water: A Precious Resource is important to learn how water is distributed, used, and conserved. The chapter clearly explains the water cycle, groundwater depletion, and rainwater harvesting.

These concepts are highly relevant for school examinations and foundation-level science preparation. Students should next read Chapter 17: Forests – Our Lifeline to understand the role of forests in maintaining ecological balance.

FAQs

Q1. What is explained in NCERT Class 7 Science Chapter 16?
The chapter explains availability of water, water cycle, groundwater, and water conservation.

Q2. Why is fresh water limited on Earth?
Most of Earth’s water is salty, and much of the fresh water is locked in glaciers and ice caps.

Q3. What is the water cycle?
The water cycle is the continuous movement of water through evaporation, condensation, and precipitation.

Q4. What is rainwater harvesting?
Rainwater harvesting is the collection and storage of rainwater for future use.

Q5. Why is NCERT Class 7 Science Chapter 16 important for exams?
It explains water resources and conservation, which are frequently asked in school and foundation-level exams.

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