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Water Resources – Class 10 Social Science notes, important questions and MCQs

NCERT Class 10 Social Science, chapter 8. Notes, key terms, important questions with answers and MCQs.

Chapter overview

Water is a renewable resource, but fresh water is limited and unevenly available. Over-use, pollution and rising demand cause water scarcity. Multi-purpose projects and traditional rainwater harvesting are two ways of managing water.

Water scarcity

About three-fourths of the earth is covered with water, but only a small share is usable fresh water.
Scarcity is caused by over-exploitation, a large and growing population, more irrigation, industrialisation, urbanisation and pollution.
Even where water is enough, it may be unfit for use because of domestic and industrial pollution.

Multi-purpose river projects

Dams are built for irrigation, electricity, water supply, flood control, recreation, inland navigation and fish breeding.
Jawaharlal Nehru called dams the 'temples of modern India'; examples are Bhakra Nangal (Sutlej) and Hirakud (Mahanadi).
Large dams cause displacement of people, loss of forests, sedimentation and changes in river ecology; the Narmada Bachao Andolan opposed the Sardar Sarovar Dam.

Rainwater harvesting

Guls or kuls are diversion channels in the western Himalayas; rooftop harvesting is common in Rajasthan, where tankas store drinking water.
Inundation channels were used in the flood plains of Bengal; khadins and johads in arid and semi-arid Rajasthan.
In Meghalaya, a 200-year-old system of tapping stream water with bamboo pipes is used; Shillong also depends on rooftop harvesting.
Gendathur village in Karnataka collects rainwater on rooftops, and Tamil Nadu made rooftop rainwater harvesting compulsory for all houses.

Key terms

Multi-purpose project: a river valley project that serves many purposes such as irrigation, power and flood control
Water scarcity: shortage of water for the needs of people, often due to over-use and unequal access
Tanka: an underground tank in Rajasthan houses that stores rainwater from rooftops
Rainwater harvesting: collecting and storing rainwater for later use

Important questions with answers

Why is fresh water a scarce resource even though water is renewable?2 marks

Only a small part of the earth's water is fresh water fit for use, and it is unevenly distributed over time and space. Over-use, pollution and the growing demand of a large population, agriculture and industry reduce the usable supply further.

Describe three traditional methods of rainwater harvesting in India.3 marks

In the western Himalayas, people built diversion channels called guls or kuls to carry water for agriculture. In the arid regions of Rajasthan, almost every house had an underground tank (tanka) to store rooftop rainwater for drinking. In Meghalaya, stream and spring water is carried through bamboo pipes for drip irrigation of crops such as black pepper.

Explain the advantages and disadvantages of multi-purpose river projects.5 marks

Advantages: they provide water for irrigation and help increase farm output; they generate hydroelectricity; they supply water for domestic and industrial use; they control floods; and they support inland navigation, fish breeding and recreation. Disadvantages: regulating the river affects its natural flow, causes excess sedimentation at the bottom of reservoirs and harms aquatic life; large areas of forest and farmland are submerged; local communities are displaced and often not properly resettled; irrigation has changed cropping patterns towards water-intensive crops and caused salinity; and dams have sometimes caused floods when water is released. Movements like the Narmada Bachao Andolan raised these concerns.

Quick revision

Fresh water is limited; scarcity is mainly man-made.
Dams = temples of modern India (Nehru).
Rooftop harvesting and tankas in Rajasthan; bamboo drip in Meghalaya.
Tamil Nadu made rooftop harvesting compulsory.

Exam tips

Make a table of harvesting methods with their regions.
In 'advantages and disadvantages of dams', write at least three points on each side.

Practice MCQs

Who called dams the 'temples of modern India'
1. Jawaharlal Nehru
2. Mahatma Gandhi
3. Sardar Patel
4. B.R. Ambedkar
Show answer
Answer: (a) Jawaharlal Nehru. He saw them as symbols of development.
Hirakud Dam is built on the river
1. Sutlej
2. Mahanadi
3. Narmada
4. Krishna
Show answer
Answer: (b) Mahanadi. It is in Odisha.
Tankas for storing rainwater are found in
1. Rajasthan
2. Kerala
3. Assam
4. West Bengal
Show answer
Answer: (a) Rajasthan. They are underground tanks in houses.
Guls or kuls are found in
1. the Western Ghats
2. the Thar desert
3. the western Himalayas
4. coastal Odisha
Show answer
Answer: (c) the western Himalayas. These diversion channels carry water for agriculture.
The Narmada Bachao Andolan opposed the
1. Bhakra Nangal Dam
2. Tehri Dam only
3. Hirakud Dam
4. Sardar Sarovar Dam
Show answer
Answer: (d) Sardar Sarovar Dam. It raised issues of displacement and environment.
Bamboo drip irrigation is practised in
1. Punjab
2. Rajasthan
3. Meghalaya
4. Gujarat
Show answer
Answer: (c) Meghalaya. Stream water is carried through bamboo pipes to plants.
Which state was the first to make rooftop rainwater harvesting compulsory for all houses
1. Rajasthan
2. Tamil Nadu
3. Karnataka
4. Kerala
Show answer
Answer: (b) Tamil Nadu. Tamil Nadu made it compulsory with legal provisions.
Which is not a disadvantage of large dams
1. displacement of local communities
2. sedimentation of reservoirs
3. flood control
4. loss of aquatic life
Show answer
Answer: (c) flood control. Flood control is a benefit of dams.

All chapters of Class 10 Social Science

Written by Kundali IQ from standard, well-established facts to help with revision. This is not an official NCERT publication; always read your textbook too.