Class 7 Science

Chapter 16: Water – A Precious Resource

                                                

STAGE 0: Foundation / Basics

Water is essential for all living beings.

Without water, life on Earth is not possible.

Sources of Water

• Rain
• Rivers
• Lakes
• Ponds
• Wells
• Groundwater

Water Cycle

The continuous movement of water between Earth and atmosphere is called the water cycle.

Steps of water cycle:

• Evaporation
• Condensation
• Precipitation

Groundwater

Water found below the surface of the Earth is called groundwater.

It is obtained through wells and hand pumps.

Depletion of Water Table

Decrease in the level of groundwater is called depletion of water table.

Main causes:

• Increase in population
• Industrial use
• Deforestation
• Lack of rainfall

Conservation of Water

Saving water is very important.

Methods to conserve water:

• Rainwater harvesting
• Reuse of water
• Fix leaking taps
• Use water carefully

Rainwater Harvesting

Collecting and storing rainwater for future use is called rainwater harvesting.

It helps to recharge groundwater.

STAGE 2: NCERT Textbook Questions & Answers

Q1. Why is water called a precious resource?

Water is limited and essential for life, so it must be used carefully.

Q2. What is groundwater?

Water found below the surface of the Earth is called groundwater.

Q3. What is rainwater harvesting?

Collecting and storing rainwater for future use.

STAGE 3: Exam-Oriented Questions

Fill in the blanks:

• The decrease in groundwater level is called __________.
• Water changes into vapour by __________.

Very Short Answer:

Name one method to conserve water.
Answer: Rainwater harvesting

Quick Revision Points

• Water is essential for life
• Groundwater is found below Earth’s surface
• Water table is decreasing
• Rainwater harvesting saves water