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NCERT Class 10 Social Science Water Resources: Exercise Solutions

Point-by-point answers for every question of End-of-chapter exercises in NCERT's Class 10 Social Science book, chapter “Water Resources”, written by Shishya. Each question is in our own short words; open the NCERT chapter for the exact wording and figures.

1. Exercises Q1(i)

   Classify each region as suffering or not suffering from water scarcity: (a) high annual rainfall (b) high annual rainfall and a large population (c) high annual rainfall but highly polluted water (d) low rainfall and low population.

   1. Region with high annual rainfall is not suffering from water scarcity as it has ample water resources.
   2. Region with high rainfall and large population suffers from water scarcity because the large population demands more water for domestic use and food production.
   3. Region with high rainfall but highly polluted water suffers from water scarcity because the water is not usable despite its availability.
   4. Region with low rainfall and low population suffers from water scarcity, because shortage of water is linked with low-rainfall and drought-prone areas even when demand is small.

   Answer: (a) not suffering; (b) suffering; (c) suffering; (d) suffering

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2. Exercises Q1(ii)

   MCQ: which is NOT an argument in favour of multi-purpose river projects? (a) they bring water to water-scarce areas (b) by regulating flow they help control floods (c) they cause large-scale displacement and loss of livelihood (d) they generate electricity for industries and homes

   1. Bringing water to dry areas, controlling floods by regulating river flow and producing electricity are all benefits, so they argue for the projects.
   2. Forcing large numbers of people to leave their land and lose their livelihoods is a harm caused by the projects, not a reason to build them.

   Answer: (c) multi-purpose projects lead to large-scale displacement and loss of livelihood

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3. Exercises Q1(iii)

   Find the mistake and correct each false statement: (a) growing cities with dense populations and urban lifestyles have helped use water properly (b) damming rivers does not affect their natural flow and sediment flow (c) in Rajasthan rooftop rainwater harvesting has become popular in spite of plenty of water from the Indira Gandhi Canal.

   1. Growing cities with dense populations and urban lifestyles have actually led to the improper use of water resources rather than helping proper utilisation.
   2. Regulating and damming rivers significantly affects the river's natural flow and its sediment flow, contrary to the false claim.
   3. In Rajasthan, rooftop rainwater harvesting is on the decline because plenty of water is available from the Indira Gandhi Canal, not gaining popularity.

   Answer: Urban growth causes improper water use; dams alter natural and sediment flow; Rajasthan's rooftop harvesting declines due to canal water availability.

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4. Exercises Q2(i)

   In about 30 words: how is water a renewable resource?

   1. Freshwater is mainly obtained from surface runoff and groundwater.
   2. This water is continually renewed and recharged through the hydrological cycle.
   3. All water moves within this cycle, ensuring it remains a renewable resource.

   Answer: Water is renewable because it is continually renewed and recharged through the hydrological cycle.

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5. Exercises Q2(ii)

   In about 30 words: what is water scarcity and what are its main causes?

   1. Water scarcity means a shortage of usable freshwater despite its abundance on Earth.
   2. It is mainly caused by over-exploitation of water resources and unequal access among social groups.
   3. Growing population and increased demand for domestic and agricultural use also drive water scarcity.

   Answer: Water scarcity is the shortage of usable freshwater, primarily caused by over-exploitation, unequal access, and rising demand from population growth.

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6. Exercises Q2(iii)

   In about 30 words: compare the advantages and disadvantages of multi-purpose river projects.

   1. Multi-purpose projects provide irrigation, electricity, and flood control to drought-prone areas.
   2. However, they cause displacement, submerge vegetation, and disrupt natural river flow.
   3. These dams also lead to sedimentation, water-borne diseases, and induced earthquakes.

   Answer: While multi-purpose projects offer irrigation and power, they cause ecological damage, displacement, and health issues.

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7. Exercises Q3(i)

   In about 120 words: how is rainwater harvested in the semi-arid regions of Rajasthan?

   1. In semi-arid and arid regions of Rajasthan, particularly in Bikaner, Phalodi, and Barmer, traditional houses have underground tanks called tankas for storing drinking water.
   2. These tankas can be very large, sometimes as big as a room, with dimensions reaching 6.1 metres deep, 4.27 metres long, and 2.44 metres wide.
   3. Rainwater falling on the sloping roofs of houses is collected and directed through pipes into these underground circular tankas built in the main house or courtyard.
   4. The stored rainwater, known as palar pani, is considered the purest form of natural water and remains available until the next rainfall.
   5. This system provides a reliable source of drinking water during summers when other sources dry up, and underground rooms adjoining the tankas help keep the house cool.
   6. Although the practice is declining due to the Indira Gandhi Canal, some households still maintain tankas because they prefer the taste of rainwater over tap water.

   Answer: Rainwater harvesting in semi-arid Rajasthan involves storing roof rainwater in large underground tankas for reliable drinking water and cooling.

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8. Exercises Q3(ii)

   In about 120 words: how are traditional rainwater harvesting methods being adapted today to conserve and store water?

   1. Rooftop rainwater harvesting is the most common modern adaptation, where water from sloping roofs is channeled into underground tanks.
   2. In Shillong, Meghalaya, nearly every household uses this system to meet 15-25 percent of their total water requirements.
   3. Villagers in Gendathur, Karnataka, have installed rooftop systems to collect and store about 50,000 litres of water annually per house.
   4. Tamil Nadu has made rooftop rainwater harvesting compulsory for all houses through legal provisions to punish defaulters.
   5. Traditional bamboo pipe systems in Meghalaya are still used to transport stream and spring water over long distances.
   6. These adaptations help conserve water by capturing runoff and storing it for domestic use, reducing dependency on other sources.

   Answer: Modern adaptations include compulsory rooftop harvesting in Tamil Nadu, widespread use in Shillong, and village-level systems in Karnataka to store rainwater.

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