NCERT Solutions for Geography Chapter 3 Social Science - Water Resources
Exercises, Page - 33
1. Multiple choice questions.
(i) Based on the information given below classify each of the situations as 'suffering from water scarcity' or 'not suffering from water scarcity'.
(a) Region with high annual rainfall.
(b) Region having high annual rainfall and large population.
(c) Region having high annual rainfall but water is highly polluted.
(d) Region having low rainfall and low population.
Answer:
suffering from water scarcity :
(c) Region having high annual rainfall but water is highly polluted.
(d) Region having low rainfall and low population.
not suffering from water scarcity :
(a) Region with high annual rainfall
(b) Region having high annual rainfall and large population.
(ii) Which one of the following statements is not an argument in favour of multipurpose river projects ?
(a) Multi-purpose projects bring water to those areas which suffer from water scarcity.
(b) Multi-purpose projects by regulating water flow helps to control flood.
(c) Multi-purpose projects lead to large scale displacements and loss of livelihood.
(d) Multi-purpose projects generate electricity for our industries and our homes.
Answer:
(a) Multi-purpose projects bring water to those areas which suffer from water scarcity.
(iii) Here are some false statements. Identify the mistakes and rewrite them correctly.
(a) Multiplying urban centres with large and dense populations and urban lifestyles have helped in proper utilisation of water resources.
(b) Regulating and damming of rivers does not affect the river's natural flow and its sediment flow.
(c) In Gujrat, the Sabarmati basin farmers were not agitated when higher priority was given to water supply in urban area, particularly during droughts.
(d) Today in Rajasthan, the practice of rooftop rainwater harvesting has gained popularity despite high water availability due to the Indira Gandhi Canal.
Answer:
(a) Multiplying urban centres with large and dense populations and urban life styles have added to water requirements.
(b) Regulating and damming of rivers affects the river's natural flow and its sediments flow.
(c) In Gujrat, the Sabarmati basin farmers were agitated when higher priority was given to water supply in urban areas, particularly during droughts.
(d) Today in Rajasthan, the practice of roof top rain water harvesting is on the decline because of high water availability due to Rajasthan Canal.
2. Answer the following questions in about 30 words.
(i) Explain how water becomes a renewable resource.
Answer:
About 3/4th of earth's surface is covered with water. But fresh water is a small proportion of it. It is obtained from the following sources :
- Surface run-off
- Ground water
- Precipitation
This water is continually being renewed and received through Hydrological cycle. All water within a Hydrological cycle makes water a renewable resource.
(ii) What is water scarcity and what are its main causes ?
Answer:
Many of our cities are such examples. Thus, water scarcity may be an outcome of large and growing population and consequent greater demands for water, and unequal access to it. A large population requires more water not only for domestic use but also to produce more food. Hence, to facilitate higher food-grain production, water resources are being over-exploitated to exapand irrigated areas for dry-season agriculture. Irrigated agriculture is the largest consumer of water. Most farmers have theit own wells and tube-wells in their farms for irrigation to increase their productivity. This has adversely affected water availability and food security of the people.
(iii) Compare the advantages and disadvantages of multi-purpose river projects.
Answer:
Many river valleys projects have been started for the purpose of integrated economic and social development of there basins.
Advantages of multipurpose projects :
- Dams are built for irrigation.
- They generate electricity.
- They provide water supply.
- They help in industrial development.
- They control floods.
- They help in recreation and navigation.
- They help in fish breeding.
Many benefits are obtained simultaneously. So they are called Multipurpose Projects.
Disadvantages of multipurpose projects : Multipurpose projects also have some disadvantages.
- They affect the natural flow of rivers.
- This results in poor sediment flow and excessive sedimentation at the bottom of the reservoir.
- It results in poorer habitats for aquatic life in the river.
- They submerge the existing vegetation and lead to soil decomposition.
- It also causes a large-scale displacement of local communities.
3. Answer the following questions in about 120 words.
(i) Discuss how rain water harvesting in semi-arid regions of Rajasthan is carried out.
Answer:
Rain water harvesting is a technique of increasing the recharge of ground water by capturing and storing rainwater. Many low cost technique are used in semi arid areas like Rajasthan. In Bikaner, Phalodi and Barmer, underground tanks or tankar are used for storing drinking water. These are connected to the sloping roofs of the houses through a pipe. Rainwater is stored in tanks for three to five years. Rainwater or Palar Pani is considered to the Purest form of natural water.
(ii) Describe how modern adaptations of traditional rainwater harvesting methods are being carried out to conserve and store water.
Answer:
In ancient India, traditional methods were and for rain water harvesting. Roof top, rainwater harvesting was commonly practised to store drinking water. People built diversion channels like 'Guls' and 'Kuls' in Himalayas. Khadins in Jaisalmer and Johads in Rajasthan store rain water. 'Tankar' were used for storing drinking water. Tankar was connected to the sloping roofs of the houses. Today, these methods were adopted to use modern methods of rainwater harvesting.