Class X - Water Resources

Class X - Water Resources

NCERT EXERCISE 

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. (not suffering from water scarcity)
(b) Region having high annual rainfall and large population. (not suffering from water scarcity)
(c) Region having high annual rainfall but water is highly polluted. (suffering from water scarcity)
(d) Region having low rainfall and low population.(not suffering from water scarcity)

(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 floods.
(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.

Ans. (c) Multi-purpose projects lead to large scale displacements and loss of livelihood.

(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 Gujarat, the Sabarmati basin farmers were not agitated when higher priority was given to water supply in urban areas, particularly during droughts.
(d) Today in Rajasthan, the practice of rooftop rainwater water harvesting has gained popularity despite high water availability due to the Rajasthan Canal.

Ans. : (a) Multiplying urban centres with large and dense populations and urban lifestyles have restricted proper utilisation of water resources.

(b) Regulating and damming of rivers affects the river’s natural flow and its sediment flow.

(c) In Gujarat, the Sabarmati basin farmers were agitatedwhen higher  prioity was given to water supply in urban areas, particularly during droughts.

(d) Today in Rajasthan, the practice of rooftop rainwater water harvesting has declined due to high water availability due to the RajasthanCanal.

Q.2. Answer the following Questions in about 30 words.

(i) Explain how water becomes a renewable resource.

 

Ans: Three-fourth of the earth’s surface is covered with water, but only a small proportion of it accounts for freshwater that can be put to use. This freshwater is mainly obtained from surface run off and ground water that is continually being renewed and recharged through the hydrological cycle. All water moves within the hydrological cycle ensuring that water is a renewable resource.

 

(ii) What is water scarcity and what are its main causes?

 

Ans: Unavailability of adequate freshwater results in water scarcity. Water scarcity in most cases is caused by over- exploitation, excessive use and unequal access to water among different social groups. 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 means 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-exploited to expand irrigated areas and dry-season agriculture.

 

(iii) Compare the advantages and disadvantages of multi-purpose river projects.

 

Ans: Advantages:

1. irrigation
2. electricity generation
3. water supply for domestic and industrial uses
4. flood control
5. recreation
6. inland navigation
7. fish breeding.

Disadvantages

1. The dams that were constructed to control floods have triggered floods due to sedimentation in the reservoir.
2. the big dams have mostly been unsuccessful in controlling floods at the time of excessive rainfall.
3. The multi-purpose projects induced earthquakes, caused waterborne diseases and pests and pollution resulting from excessive use of water.
4. Multi-purpose projects lead to large scale displacements and loss of livelihood.
5. Regulating and damming of rivers affect their natural flow causing poor sedimentation at the bottom of the reservoir, resulting in rockeir stream beds and poorer habitats for the rivers' aquatic life.
6. Resistance to these projects has primarily been due to the large-scale displacement of local communities.
7. Has also changed the cropping pattern of many regions with farmers shifting to water intensive and commercial crops, has great ecological consequences like salinisation of soil, has increased the social gap between the richer landowners and the landless poor.
8. Inter-state water disputes are also becoming common with regard to sharing the costs and benefits of the multi-purpose project.

Q.3. Answer the following Questions in about 120 words.

(i) Discuss how rainwater harvesting in semi-arid regions of Rajasthan is carried out.

 

Ans: ‘Rooftop rain water harvesting’ was commonly practised to store drinking water, particularly in Rajasthan -

             

In the semi-arid and arid regions of Rajasthan almost all the houses traditionally had

underground tanks or tankas for storing drinking water. The tanks could be as large as

a big room; one household in Phalodi had a tank that was 6.1 metres deep, 4.27 metres long and 2.44 metres wide. The tankas were part of the well-developed rooftop rainwater harvesting system and were built inside the main house or the courtyard. They were connected to the sloping roofs of the houses through a pipe. Rain falling on the rooftops would travel down the pipe and was stored in these underground ‘tankas’. The first spell of rain was usually not collected as this would clean the roofs and the pipes. The rainwater from the subsequent showers was then collected. The rainwater can be stored in the tankas till the next rainfall making it an extremely reliable source of drinking water when all other sources are dried up, particularly in the summers.

 

 

(ii) Describe how modern adaptations of traditional rainwater harvesting methods are being carried out to conserve and store water.

 

Ans:     • Roof top rain water is collected using a PVC pipe

            • Filtered using sand and bricks

            • Underground pipe takes water to sump forimmediate usage

            • Excess water from the sump is taken to the well

            • Water from the well recharges the underground

            • Take water from the well (later)