1. Chapter at a Glance

Water covers most of the Earth, but most of it is salty sea water. Only a very small amount is freshwater, which people, animals and plants need to drink, grow food and live. If all the water on Earth were in one glass, the freshwater would fit in a teaspoon.

Water exists in three forms: solid (ice, snow), liquid (rain, rivers) and vapour (steam). Heat from the Sun turns water from oceans and rivers into vapour. The vapour forms clouds and comes back as rain, snow or hail. This never-ending journey is called the water cycle. Some rainwater sinks into the soil and is stored underground as groundwater, while rivers, lakes and ponds hold surface water.

Rivers start in the mountains and flow down, following the shape of the land. Some flow into the Bay of Bengal and some into the Arabian Sea. Ponds, lakes and rivers are home to many plants and animals with special features for living in water. Since freshwater is so limited, we must use it wisely and save it.

2. Word Meanings

3. Important Topics

A. How Much Water Do We Have?

• Most of the Earth’s surface is covered with water, but most of it is salty.
• Only a small amount is freshwater, which is needed for drinking, farming and daily work.
• If all the water on Earth were in a 200 ml glass, the freshwater would be only 5 ml, about a teaspoon.
• Seawater cannot be drunk, but it is used to make salt. The salt pans of Gujarat are among India’s largest salt-producing areas.

B. Sources of Freshwater

• Rain, rivers, lakes, ponds, wells, springs and glaciers.
• Wular Lake in Jammu and Kashmir is one of the largest freshwater lakes in Asia. It helps prevent floods.

C. Forms of Water

• Ice melts into water when kept outside.
• Water turns into steam when heated.
• Water vapour in the air turns into droplets on a cold glass.

D. The Water Cycle

1. The Sun heats water in oceans, rivers and lakes.
2. The water turns into water vapour and rises.
3. The vapour cools and forms clouds.
4. Clouds bring rain, snow or hail.
5. The water returns to rivers, lakes and oceans, and the cycle continues.

E. Groundwater

• Some rainwater soaks into the soil and sinks through layers of soil and rock.
• Water stored deep underground is called groundwater.
• We get it through wells, borewells, tube wells and handpumps.
• Concrete roads and cemented areas stop rainwater from going underground.
• Open ground, soak pits, ponds, lakes and trees help recharge groundwater.
• Johads in Rajasthan are small earthen dams that collect rainwater.
• Hiware Bazar in Maharashtra is a water-positive village because of rainwater harvesting.

F. Surface Water and Rivers

• Rivers usually begin in mountains and flow down across the land.
• Water flows, stops or curves according to the shape of the land. Flowing water can also change the shape of the land.
• Some rivers flow into the Bay of Bengal (like the Ganga, Godavari, Krishna and Mahanadi) and some into the Arabian Sea (like the Narmada and Tapi).
• The Luni river in Rajasthan is the only major Indian river that does not reach a sea. It ends in the Rann of Kutch.

G. Life in Water

• Aquatic animals have special features, like fins for swimming and gills for breathing in water.

• Leaves of many plants have a waxy coating that keeps water out, like wax crayon on paper.
• Keibul Lamjao National Park in Manipur is the only floating national park in the world. It has floating islands called phumdis and the Sangai deer.

H. Save Water

Freshwater is limited. Collect rainwater, don’t waste water and keep water bodies clean.

4. Question-Answers

Very Short Answer Questions

1. Is most of the water on Earth fresh or salty?
Salty.

2. Name the three forms of water.
Solid, liquid and vapour.

3. What is the solid form of water?
Ice or snow.

4. What is the water stored deep under the ground called?
Groundwater.

5. What are johads?
Small traditional earthen dams in Rajasthan that collect rainwater.

6. Which Indian river does not drain into a sea?
The Luni river.

7. Where are the salt pans that produce a lot of India’s salt?
In Gujarat.

8. Name the only floating national park in the world.
Keibul Lamjao National Park, Manipur.

9. Which animal of the wetlands has partly webbed paws?
The fishing cat.

10. Name a free-floating water plant.
Water hyacinth.

Short Answer Questions

1. Why can’t we drink ocean water?
Ocean water is very salty. Drinking it makes us more thirsty and harms our body, so it is not fit for drinking.

2. What is the water cycle?
The Sun heats water, which turns into vapour and forms clouds. The clouds bring rain or snow, and the water goes back to rivers and oceans. This constant circular movement of water is the water cycle.

3. How is groundwater formed?
When it rains, some water soaks into the soil. It sinks through the layers of soil and rock and is stored deep underground as groundwater.

4. Why is groundwater not recharged well in cities?
Cities have many cemented roads and buildings. Rainwater cannot soak into the ground through these hard surfaces.

5. How can we help rainwater go back underground?
By keeping open spaces, making soak pits, ponds and lakes, and planting more trees.

6. How do plants in water stay healthy?
Many leaves have a waxy coating that makes them waterproof. It stops too much water from getting inside the plant.

Long Answer Questions

1. How do rivers flow? Explain with the mustard seed activity.
Rivers begin high in the mountains and flow down across the land. In the activity, mustard seeds poured on crumpled paper rolled from the highest point to the lower parts. They did not go in a straight line but followed the slopes and collected in low areas. Rivers flow the same way: they follow the shape of the land, curve around hills and collect in low areas like lakes. Because of the slope of the land, some rivers flow into the Bay of Bengal and some into the Arabian Sea.

2. Why is freshwater precious? How can we save it?
Freshwater is only a very small part of all the water on Earth, and all living beings need it to survive. We use it for drinking, cooking, farming and cleaning. We can save it by closing taps, fixing leaks, harvesting rainwater, reusing water for plants and keeping rivers and ponds clean.

Textbook Exercise Answers (Let us reflect)

1. Match the following.

2. Why can’t most of the water on Earth be used for drinking or farming?
Most of the water on Earth is salty sea water. Salty water harms our body and damages crops and soil.

3. Why do many living beings live near water bodies?
All living beings need water to live. Water bodies give them water to drink, food and a safe home.

4. What would happen if it did not rain in your region for two years?
Wells, ponds and rivers would dry up. There would be no water for drinking or farming, crops would fail, animals would suffer and people might have to move away.

5. What happens to rainwater in a forest compared to a city?
In a forest, trees and soft soil help rainwater soak into the ground and recharge groundwater. In a city, most rainwater runs off concrete surfaces into drains, and roads may flood.

6. Design a house or school that saves water. What would it include?
Sample answer: A rooftop rainwater harvesting system, a covered tank to store rainwater, a soak pit, taps that close automatically, reuse of wash water for plants, and a green lawn instead of cement.