DAV Class 4 Science Chapter 8 Question Answer Water Scarcity and Conservation of Water

If you are looking for DAV Class 4 Science Chapter 8 Question Answer Water Scarcity and Conservation of Water of My Living World science book, then you are at the right place. Here at NCERTBooksPDF, Class 4 Science Chapter 8 exercises are solved with accurate, child-friendly explanations, clear matching tables, and complete solutions to help DAV students score top marks in their exams.

Table of Contents

• DAV Class 4 Science Chapter 8 Water Scarcity Solutions
• A. Fill in the Blanks
• B. Match the Following
• C. Tick the Correct Option
• D. Answer the Following Questions in Brief
• E. Answer the Following Questions (Detailed Explanations)
• Value-Based Questions
• Something to Do

DAV Class 4 Science Chapter 8 Water Scarcity Solutions

DAV Class 4 Science Chapter 8 Water Scarcity and Conservation of Water explores the importance of fresh water, causes of water depletion (deforestation, population growth, industrialization), rainwater harvesting, and modern irrigation methods. Below are the complete textbook solutions.

A. Fill in the blanks.

1. The earth is known as a blue planet.
2. Rain and snow are two major natural sources of water.
3. Setting-up of factories causes a decrease / depletion in the level of underground water.
4. Cutting of trees in the forests causes a decrease in rainfall.
5. Use of water sprinkler for irrigation reduces wastage of water.

Answer: (1) blue  |  (2) Rain, snow  |  (3) decrease  |  (4) decrease  |  (5) wastage

B. Match the following:

Answer: (1) c, (2) d, (3) a, (4) b

C. Tick (✓) the correct option.

1. Two major natural sources of water are—
(a) rain and wells
(b) snow and rivers
(c) rain and snow
(d) groundwater and rivers

Answer: (c) rain and snow
Explanation: Rain and melting snow on high mountains are the two primary natural precipitation sources that feed rivers, lakes, and underground aquifers.

2. Planting of more trees will help in—
(a) reducing the ground water level
(b) setting-up more factories
(c) deforestation
(d) increasing the rainfall

Answer: (d) increasing the rainfall
Explanation: Trees release water vapor into the air through transpiration, which helps clouds condense and increases natural rainfall.

3. We can avoid wastage of water by—
(a) using water sprinkler for irrigation
(b) over-irrigation of fields
(c) washing our car with a jet of water
(d) allowing water to leak from taps

Answer: (a) using water sprinkler for irrigation
Explanation: Sprinkler and drip irrigation spray measured water droplets over crops without pooling or wasteful surface runoff.

D. Answer the following questions in brief.

1. How much of the surface of earth is covered by water?
Answer: Nearly three-fourths (about 71%) of the Earth’s surface is covered by water.

2. Name three sources of fresh water.
Answer: Rivers, Lakes, and Ponds (or rain and underground water).

3. State the effect of deforestation on rainfall.
Answer: Cutting down forests decreases transpiration, which reduces cloud formation and leads to a significant decrease in rainfall and recurring droughts.

4. State two reasons that are leading to clearing of forests.
Answer:
(i) Rapidly expanding human population requiring more agricultural land, housing colonies, roads, and factories.
(ii) High demand for wood as timber for construction, furniture, paper making, and fuel.

5. State one utility of dams.
Answer: Dams hold back and store large volumes of river water to generate clean hydroelectricity and provide controlled water for canal irrigation while preventing floods.

E. Answer the following questions.

1. State three factors that are responsible for water scarcity.
Answer: Three main factors causing water scarcity are:

1. Rapid Population Growth: Greater demand for clean drinking water, sanitation, food cultivation, and urban construction.
2. Deforestation: Large-scale destruction of forests reduces natural rainfall and disrupts the groundwater recharge cycle.
3. Industrial Expansion: Factories extract massive volumes of groundwater through deep borewells and pollute fresh water bodies with untreated toxic effluents.

2. How does setting-up of factories affect the ground water level?
Answer: Industrial manufacturing requires huge quantities of water for cooling machinery, processing chemicals, and washing products. Factories install powerful electric tube wells that pump out groundwater day and night much faster than natural rainwater can replenish it, causing the underground water table to drop drastically.

3. State two ways to do rain-water harvesting.
Answer: Two practical methods of rainwater harvesting are:

1. Rooftop Rainwater Harvesting: Rainwater falling on building rooftops is collected through pipes, passed through a basic gravel filter, and stored in underground tanks or masonry cisterns for non-drinking household chores.
2. Groundwater Recharge Pits: Surface rainwater runoff from open grounds and roads is channeled into deep recharge pits or trenches, allowing clean water to seep underground and raise the local water table.

4. How should the fields be irrigated to reduce wastage of water?
Answer: Agricultural fields should be irrigated using precision water-saving technologies:

• Drip Irrigation System: Narrow plastic pipes fitted with drippers deliver water slowly drop-by-drop directly to the root zone of plants, preventing evaporation and weed growth.
• Sprinkler Irrigation System: Rotating sprinkler nozzles spray water in fine mist droplets over crops like natural rain, preventing soil erosion and wasteful deep pooling.

5. State any three ways of conserving water at home.
Answer:

1. Turn off the faucet while brushing teeth, soaping hands, or lathering hair, and bathe using a bucket and mug instead of an open shower.
2. Repair leaking taps, flush tanks, and dripping pipes immediately.
3. Reuse water used for washing vegetables, dal, or rice, as well as waste water from RO purifiers, to water houseplants and wash outdoor floors.

Value-Based Questions

One day, when Aparna’s mother was cooking food, Aparna asked her if she could help her. Her mother asked Aparna to wash rice in a bowl with water. She then told Aparna to pour the used water onto the plants in their garden. Aparna was a little surprised, but she followed her mother’s instructions. Later, her mother explained why she had asked Aparna to pour the used water onto the plants.

1. What reason may have been given by Aparna’s mother?
Answer: Aparna’s mother explained that clean fresh water is a scarce and precious resource that should not be wasted down the drain. Reusing water that washed rice saves fresh tap water and provides plants with starch and minerals dissolved in the water.

2. State the values displayed by Aparna and her mother.
Answer:

• Aparna’s mother: Resourcefulness, conservation mindset, environmental awareness, and educating her daughter through positive daily habits.
• Aparna: Willingness to assist in household chores, obedience, attentiveness, and eagerness to learn.

3. Suggest another way in which the used water could have been utilised.
Answer: The used rinse water could also be used to soak dirty cooking utensils before scrubbing or to mop the kitchen floor.

Something to Do

1. Water Conservation Survey: Prepare a mini questionnaire to survey 5 neighbors on how they wash vehicles (bucket vs hose pipe) and whether they turn off taps while brushing teeth.

2. Save Water Posters: Design colorful posters with catchy slogans like “Save Water, Save Life” and “Every Drop Counts” for school display boards.

Related Chapters:

• DAV Class 4 Science Solutions (All Chapters)
• DAV Class 4 Science Chapter 7 Food
• DAV Class 4 Science Chapter 9 Safe Handling and Storage of Water