NCERT Solutions Class 10 Social Science Chapter 3 Water Resources

NCERT Solutions for Class 10 Social Science Geography for chapter 3 Water Resources

Water Resources
Key Points and Definitions:
1. 96.5 per cent of the total volume of world's water is estimated to exist as oceans and only 2.5 percent as freshwater.
2. India receives nearly 4 percent of the global precipitation and ranks 133 in the world in terms of water availability per person per annum.
3. By 2025. it is predicted that large parts of India will join countries or regions having absolute water scarcity
4. Water scarcity in most cases is caused by over- exploitation, excessive use and unequal access to water amot different social groups.
5. Water resources are being over-exploited to expand irrigated areas and dry-season agriculture.
6. Intensive industrialisation and urbanisations has made matters worse by exerting pressure on existing freshwater resources.
7. Water bodies are polluted by domestic and industrial wastes, chemicals, pesticides and fertilisers used in agriculture
8. In the first century B.C.. Sringaverapura near Allahabad had sophisticated water harvesting system channelling the flood water of the river Ganga.
9. In the 11th Century. Bhopal Lake, one of the largest artificial lakes of its time was built.
10. Dam is a barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment.
11. Jawaharlal Nehru proudly proclaimed the dams as the 'Temples of modern India'.
12. Narmada Bachao Andolan' and the 'Tehri Dam Andolan' were started against large multi-purpose river projects.
13.

Question. Which of the following is not the cause of water scarcity?
(a) Growing population
(b) Expansion of irrigation facilities
(c) Industries
(d) Water harvesting technique
Answer. D

Question. Bhakra Nangal River Valley Project is made on the river:
(a) Sutlej-Beas
(b) Ravi-Chenab
(c) Ganga
(d) Son
Answer. A

Question. Hirakud Dam is constructed on the river:
(a) Ganga
(b) Manjira
(c) Manas
(d) Mahanadi
Answer. D

Question. The diversion channels seen in the Western Himalayas are called:
(a) Guls or Kuls
(b) Khadins
(c) Johads
(d) Recharge pits
Answer. A
 

Question. Which was the largest artificial lake of ancient India built in the 11th century?
Answer. Bhopal Lake

Question. Name the oldest water-harvesting system channeling the flood water of river Ganga.
Answer. Sringaverapura near Allahabad

Question.Which river is known as "River of Sorrow" in Jharkhand and West Bengal?
Answer. Damodar River

Question. Why do some people oppose dams?
Answer. Dams may submerge the land for cultivation and disrupt the lives of the displaced people

Question. Choose the correct match-
(a) Tankas .............................................. Bikaners
(b) Bamboo drip irrigation system ................................ Madhya Pradesh
(c) Ganga ................................................ Hirakud Dam
Answer. A

State whether the following statements are True or False-

Question. Bamboo drip irrigation system is followed in Uttar Pradesh.
Answer. False

Question. 'Narmada Bachao Andolan' was started against large multi-purpose river projects
Answer. True

Question. India receives nearly 9 per cent of the global precipitation.
Answer. False

Fill in the blanks-

Question. Water of Bhakra Nangal Project is being used mainly for ..........
Answer. Hydel power and irrigation

Question. In Western Rajasthan today plenty of water is available due to ........
Answer. Perennial Rajasthan Canal

Question. is a resistance to multi-purpose projects
Answer. Narmada Bachao Andolan

Question. In the question given below.there are two statements marked as Assertion (A) and Reason (R).Mark your answer as per the codes provided below :
(A) Local communities oppose Dams.
(R) Dams may submerge the land for cultivation and disrupt the lives of the displaced people.
Options:
(1) Both A and R are true and R is the correct explanation of
(2) Both A and R are true but R is not the correct explanation of
(3) A is true but R is False
(4) A is false but R is true.
Answer. A

Question. In the question given below.there are two statements marked as Assertion (A) and Reason (R).Mark your answer as per the codes provided below :
(A) India's rivers, especially the smaller ones, have all turned into toxic streams.
(R) Dams were traditionally built to impound rivers and rainwater that could be used later to irrigate agricultural fields.
Options:
(1) Both A and R are true and R is the correct explanation of
(2) Both A and R are true but R is not the correct explanation of A
(3) A is true but R is False.
(4) A is false but R is true
Answer. B

NCERT Solutions for Class 10 Social Science Chapter 3 Water Resources Very Short Answer Questions

Question. How is freshwater obtained?
Answer. Mainly obtained from surface run off and groundwater.

Question. What is water scarcity?
Answer. Lack of freshwater resources to meet water demand.

Question. Explain the causes of water scarcity.
Answer. Over-exploitation, excessive use and unequal access to water among different social groups.

Question. What was the method used in ancient period to conserve water?
Answer. Dams built of stone rubble, reservoirs or lakes, embankments and canals for irrigation.

Question. What is a dam?
Answer. A barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir.

Question. What are the benefits of dams?
Answer. Irrigation, electricity generation, water supply for domestic and industrial uses, flood control, recreation, inland navigation and fish breeding.

Question. Why were multi-purpose projects launched after independence of India?
Answer. Multipurpose projects, were thought of as the vehicle that would lead the nation to development and progress, overcoming the handicap of its colonial past.

Question. What were ‘Kuls’ or ‘Guls’?
Answer. These are the diversion channels for irrigational purposes. These are mainly used in western Himalayas for water harvesting and agriculture.

Question. How did people in West Bengal practise water harvesting?
Answer. People developed inundation channels to irrigate their fields.

Question. What were ‘johads’ and ‘khadins’?
Answer. In arid and semi-arid regions, agricultural fields were converted into rain fed storage structures that allowed the water to stand and moisten the soil. These were called ‘khadins’ in Jaisalmer and ‘Johads’ in other parts of Rajasthan.

Question. What are ‘tankas’?
Answer. Tankas were underground storing tanks of drinking water in arid and semi-arid regions of Rajasthan. Tankas were big huge tanks for storing rain water from the roof top of all the houses.

Question. Which state has made rooftop rainwater harvesting compulsory?
Answer. Tamil Nadu.

Question. What is bamboo drip irrigation?
Answer. In Meghalaya, a 200 year old system of tapping stream and spring water by using bamboo pipes, is practised.

 

NCERT Solutions for Class 10 Social Science Chapter 3 Water Resources Short/Long Answer Type Questios 

Question. Write three sources of fresh water.
Answer. (1) Precipitation - from rainfall.
(2) Surface water - in rivers, lakes, etc.
(3) Ground water - water stored in underground acquifers which gets recharged by rainfall

Question. What is water scarcity? Write the main reasons for water scarcity.
Answer. means shortage of water.
1. Large growing population
2. water resources are being over-exploited to expand irrigated areas
3. greater demand for water with growing urbanisation and industrialisation.
4. unequal access to water among different social groups
5. Excessive use of water by industries
6. Over exploitation of water in the urban areas

Question. Write the main causes of water pollution.
Answer. 1. Domestic wastes,
2. lndustrial wastes are disposed off in the water without proper treatment.
3. Chemical effluents from industries and from agricultural sector.
4. Pesticides and fertilisers used in agriculture
5. Many human activities, e.g., religious rituals and immersing of idols, etc. in the water also pollute water.

Question. What is the need for conservation of water resources?
Answer. (1) Water resources are limited and our requirements are increasing day by day.
(2) Most of our resources are polluted and unsuitable for drinking and other purposes.
(3) To safeguard ourselves from health hazards.
(4) To ensure food security and for continuation of our livelihoods.
(5) To prevent degradation natural ecosystem.of our water bodies

Question. Write some measures adopted for conservation of water resources.
Answer. 
(1) Do not overdraw the ground water, recharge the ground water
(2) Avoid wastage of water at all levels.
(3) Do not pollute the water.
(4) tapping the rainwater in reservoirs, watershed development programmes, etc.
(5) Drip irrigation and sprinklers etc., especially in dry areas

Question. How was water conserved in ancient India? Give any four examples in support of your answer.
Answer. (1) In the first century B.C., Allahabad had sophisticated water harvesting system
(2) During the time of Chandragupta Maurya, dams, lakes and irrigation systems were extensively built.
(3) Sophisticated irrigation works have been found in Kalinga in Odisha, Nagarjunakonda in Andhra Pradesh, Bennur in Karnataka and Kolhapur in Maharashtra.
(4) Bhopal lake, built in the 11th century, was one of the largest artificial lakes of its time.
(5) In the 14th century, lltutmish constructed a tank in Hauz Khas,Delhi for supplying water in Siri Fort area.

Question. Give a short note on Multi-purpose projects In India.
Answer. 1. launched after Independence with their integrated water resources management approach
2. Jawaharlal Nehru proudly proclaimed the dams as the 'temples of modern India';
3. lt would integrate development of agriculture and the village economy with rapid industrialisation and growth of the urban economy.

Question. Give four major uses of water.
Answer. 1. Drinking and domestic consumption like washing clothes.
2. Irrigation of farm lands.
3. Generation of Hydro-electricity.
4. Uses in industrial establishments.

Question. What is Palar Pani? What is its significance in the arid regions of Rajasthan?
Answer. The rainwater which is stored in underground tanks is potable water.
It is called Palar Pani. In the arid regions of Rajasthan, it is important in the following ways.
• It is the main source of drinking water, when all other sources have dried up.
• It is considered the purest form of drinking water.
• In summer, these tanks would keep the underground rooms cool, adjoining them, clean.

Question. Describe any three different rainwater harvesting systems practised in India.
Answer. In hills and mountainous regions, people built diversion channels like guls or kuls for agriculture.
• Inundation channels were built in the floodplains of Bengal,
• In arid and semi-arid regions of Rajasthan, agricultural fields were converted into rainfed storage structures

Question. Why dams are now referred as multi-purpose projects?
Answer. (a) The uses of the impounded water are in integration with one another.
(b) Dams are constructed to flood control, irrigation, generation and distribution of electricity.
(c) Dams are constructed to conserve water, vegetation and soil.
(d) It also helps to promote tourism.

Question. Mention the negative effect of over irrigation?
Answer. 
(a) This has great ecological consequences like Stalinization of the soil.
(b) Decrease the soil fertility.
(c) It leads to water scarcity.

 

 

NCERT Solutions for Class 10 Social Science Chapter 3 Water Resources 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:
(a) Not suffering from water scarcity
(b) Suffering from water scarcity
(c) Suffering from water scarcity
(d) Not suffering from water scarcity

(ii) Which one of the following statements is not an argument in favour of multi-purpose river projects?
(a) Multi-purpose projects bring water to those areas which suffer from water scarcity.
(b) Multi-purpose projects by regulating water flow help 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.
Answer: (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.
Answer:
(a) Multiplying urban centres with large and dense populations and urban lifestyles have caused the over exploitation of water resources.
(b) Regulating and damming of rivers affect their natural flow and causes the sediment to settle at the bottom of the reservoir.
(c) In Gujarat, 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 rooftop rainwater harvesting is on the decline due to the Rajasthan canal.

2. Answer the following questions in about 30 words
(i) Explain how water becomes a renewable resource.
Answer: Water is a renewable resource as it is renewed by hydrological cycle itself through the processes of evaporation, condensation, and precipitation. The process of hydrological cycle is never ending and hence, water is a renewable resource.

(ii) What is water scarcity and what are its main causes?
Answer: Water scarcity is the lack of sufficient available water resources to meet water needs within a region. It is caused by an increase in population, growing demand for water, and unequal access to it.

(iii) Compare the advantages and disadvantages of multi-purpose river projects.
Answer:
Advantages: Multipurpose river projects help in irrigation, electricity production, flood control, inland navigation, fishing, etc.

Disadvantages: The reservoirs destroy local flora and fauna and displace millions of people. Many native villages are submerged, and people lose their livelihood, with little or no hope of rehabilitation. Dams have also led inter-state water disputes and have triggered floods due to sedimentation in the catchment area. Scientist also associates large dams with causing of earthquakes and spread of water-borne diseases in the surrounding areas.

3. Answer the following questions in about 120 words
(i) Discuss how rainwater harvesting in semi-arid regions of Rajasthan is carried out.
Answer: Houses in the semi arid regions of Rajasthan have traditionally constructed tanks for storing drinking water. The tanks are constructed inside the main house, and are a part of the well-developed rooftop rainwater harvesting system. They are connected to the sloping roofs of the houses through a pipe. The rainwater falling on the rooftop is stored in the tanks. The first spell of rainwater is not collected due to its impurities. The rainwater or palar pani as commonly known in these parts is considered 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 many parts of India rooftop rainwater harvesting is being successfully adopted to store and conserve rainwater. In Gendathur village, Mysuru, Karnataka about 200 households have adopted the rooftop rainwater harvesting method, thereby making the village rich in rainwater. The state of Tamil Nadu is the first state of India, which has made it compulsory for all the houses to have rooftop rainwater harvesting structures. Defaulters are severely punished. Therefore, in modern homes rooftop rainwater is becoming more popular. Drains from rooftop are channelised to underground tank. The water is filtered, purified, and then stored. In air and semi arid regions, agricultural field were converted into rain fed storage structures that allowed the water to stand and moisten the soil.

 

NCERT Solutions for Class 10 Social Science Chapter 3 Water Resources Short Answer Questions 

Question. What are the main causes of water scarcity?
Answer. (i) Overpopulation: Water scarcity may be an outcome of a large and growing population which results in greater demand for water and unequal access to it.
(ii) Commercialisation of agriculture: After the success of the Green Revolution, farmers are producing commercial crops. The commercial crops need more water for irrigation.
(iii) Urbanisation: Urbanisation is another factor for scarcity of water. Since new lifestyles have developed in the urban cities overexploitation of water continues; there is water scarcity.

Question. Explain ‘Narmada Bachao Andolan’.
Answer. 
- Save Narmada Movement is a Non-Governmental Organisation.
- It mobilised tribal people, farmers, environmentalists and human rights activists against the Sardar Sarovar Dam, being built across the Narmada river in Gujarat.
- It focused on the environmental issues related to trees that would be submerged under the dam water.
- Recently, it has refocused its aim to rehabilitate displaced people. 

Question. Give various methods of rainwater harvesting since ancient times.
Answer. (i) Guls or Kuls: In hilly and mountainous regions, people built diversion channels called Kuls or Guls in the Western Himalayas. A Kul or Gul leads to a circular village tank, from which water is released as and when required.
(ii) Inundation Channels: In the flood plains of Bengal, people developed inundation channels to irrigate their fields.
(iii) Khadins and Johads: In arid and semi-arid regions, agricultural fields were converted into rain fed storage structures that allowed the water to stand and moisten the soil, called ‘Khadins’ in Jaisalmer and ‘Johads’ in other parts of Rajasthan.
(iv) Tankas: Cirular holes are made in the ground, lined with fine polished line. In Bikaner, Phalodi and Barmer of Rajasthan, almost all the houses traditionally had underground tanks or tankas for storing drinking water.

Question. What do you understand by the term ‘scarcity of water’?
Answer. It is a situation where water is sufficiently available to meet the needs of the people, but the area still suffers from water scarcity.
(i) This scarcity may be due to bad quality of water.
(ii) There has been a growing concern that even if there is ample water to meet the needs of the people, much of it may be polluted by domestic and industrial wastes, chemicals, pesticides and fertilisers used in agriculture, thus, making it hazardous for human use.

Question. What are the main factors of river pollution in India?
Answer. (i) India’s rivers, especially the smaller ones have all turned into toxic streams. Even the big ones like Ganga and Yamuna are far from being pure.
(ii) The assault on Indian rivers is from the population growth. It increases the pollution in the river and reduces the amount of water available for industries and agriculture.
(iii) Besides that, other culprits are the modernisation of agriculture, urbanisation and the growth of industries. The chemical fertilisers and the effluents from industries on the river banks are also responsible for its pollution.

Question. What is a dam? What are the different types of dams?
Answer. A dam is a barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment.
Dams are classified according to their structure, intended purpose or height. On the basis of structure and material used, dams are classified as:
(i) Timber dams
(ii) Embankment dams or masonry dams.
According to their height, dams can be categorised as:
(i) Large dams or major dams
(ii) Low dams
(iii) Medium height dams
(iv) High dams

Question. Why did Jawaharlal Nehru proudly proclaim the dams as the ‘temples of modern India’?
Answer. Multipurpose projects launched after independence with their integrated water resources management approach, were thought of as the vehicle that would lead the nation to development and progress. Jawaharlal Nehru proclaimed the dams as the temples of modern India’ as it would integrate the development of agriculture and village economy with rapid industrialisation and growth of the urban economy.

Question. Explain the river-water dispute between the states of India.
Answer. Major river water disputes are as follows:
Krishna-Godavari dispute is due to the objections raised by the governments of Andhra Pradesh and Karnataka. It is regarding the diversion of more water at Koyna by the Maharashtra government for a multipurpose project. This would reduce downstream flow in their states with adverse consequences for agriculture and industry. Similar disputes arise as Kaveri issue between the states of Karnataka and Tamil Nadu, and Yamuna water dispute between Haryana and Delhi governments regarding the use of water.

Question. How do dams create conflicts between people?
Answer. (i) In Gujarat, the Sabarmati–basin farmers were agitated and almost caused a riot over the higher priority given to water supply in urban areas, particularly during droughts.
(ii) Interstate water disputes are also becoming common with regard to sharing the costs and benefits of the multi-purpose projects.

Question. How are dams responsible for causing floods?
Answer. (i) Ironically, the dams that were constructed to control floods have triggered floods due to sedimentation in the reservoir.
(ii) Big dams can be unsuccessful in controlling floods at the time of excessive rainfall.
(iii) Release of water from dams during heavy rains aggravate the flood situation.

Question. Is rain water harvesting practised these days in western Rajasthan? Support your answer.
Answer. These days, in western Rajasthan, sadly the practice of rooftop rainwater harvesting is on the decline as plenty of water is available due to the perennial Rajasthan Canal, though some houses still maintain the tankas since they do not like the taste of tap water. 

 

NCERT Solutions for Class 10 Social Science Chapter 3 Water Resources Long Answer Questions

Question. “India is heading towards water scarcity.” Trace the possible solutions to tackle this problem.
Answer. The major concern now in the country is water scarcity, which can be tackled with the help of following methods:
(i) Interlinking of the rivers.
(ii) Rainfall in India is the second highest, i.e., after Brazil. But the distribution is highly uneven. Certain channeling like by oil companies can solve the problem of distribution of water.
(iii) Third major problem causing water scarcity is pollution, which can be tackled with the help of 3R (reduce waste, reuse waste, recycle waste) as waste is nothing but unused resources.
(iv) Overuse and wastage of water in day to day life activities need to be controlled.
(v) Thermal pollution need to be inhibited.
(vi) Bottled water or water packaging industries need to be dominated by strong hands and law regarding extraction of ground water should be there.
(vii) Over irrigation and agricultural industry need to consider the decreasing trend of ground water.
(viii) India is a land of festivals. All idols that are worshipped during festivals are thrown in river, causing pollution need to be tackled.
(ix) Proper disposal of waste, otherwise leachets may pollute groundwater. There are many more reasons.
(x) Rainwater harvesting and Bamboo drip irrigation system can help a lot.

Question. In what ways are intensive industrialisation and urbanisation responsible for water scarcity?
Or
“It is essential to conserve and manage our water resources.” Support the statement with suitable examples.
Answer. (i) The ever increasing number of industries has made matters worse by exerting pressure on
(ii) Industries, apart from being heavy users of water, also require power to run them. Much of this energy comes from hydroelectric power.
(iii) Multiplying urban centres with large and dense populations and urban lifestyles have not only added to water and energy requirements but have further aggravated the problem.
(iv) In housing societies or colonies, we would find that most of these have their own groundwater pumping devices to meet their water needs. With the result, fragile water resources are being overexploited and have caused their depletion in several cities.

Question. How have multi-purpose projects and large dams been the cause of many new social movements?
Answer. (i) Narmada Bachao Andolan and the Tehri Dam Andolan, etc., were the movements to resist large-scale displacement of local communities. Local people often had to give up their land,livelihood and their control over resources for the greater good of the nation.
(ii) Irrigation has changed the cropping pattern from shifting to commercial crops. It is responsible for salinisation of the soil. At the same time, it has its social impact by increasing the social gap between the rich landowners and the landless poor.
(iii) Dams also created conflicts between people wanting different uses and benefits from the same water resource. In Gujarat, the Sabarmati basin farmers were agitated over the priority given to water supply in urban areas, particularly during droughts.
(iv) Interstate water disputes are also common with regard to sharing the costs and benefits of the multi-purpose projects. For e.g., Krishna-Godavari dispute, is due to the objections raised by Karnataka and Andhra Pradesh governments regarding the diversion of more water at Koyna by the Maharashtra government for a multi-purpose project.

Question. Analyse the impact of ‘ water scarcity’. 
Answer. Water scarcity is the lack of freshwater resources to meet water demand. It is affecting every continent and as per the World Economic Forum, it is one of the largest global risks in terms of potential impact over the next decade. One-third of the global population (2 billion people) live under conditions of severe water scarcity at least 1 month of the year. Half a billion people in the world face severe water scarcity all year round. Half of the world’s largest cities experience water scarcity. The effects of water scarcity can be grouped into these 4 broad areas— Health, Hunger, Education, and Poverty.
Health: In many developing countries, people are forced to drink low quality water from flowing streams, many of which are contaminated. There are many water-borne diseases that people die off.
Less water also means sewage does not flow, and mosquitoes are other insects breed on still (stagnant) dirty water. The result is deadly malaria and other infections.
Lack of water or quality water causes huge sanitation issues. Clinics, local restaurants, public places of convenience and many other places are forced to use very little water for cleaning. This compromises the health of the staff and people who use the facilities.
Education: It is a bit hard to see how water and education is related. In many continents, children have to be up at dawn to collect water for the family. They have to walk for several miles to get water. The children get tired and some have to miss school as a result. At many places, girls and women are not allowed to go to school at all so that they can serve the family by getting water and taking care of other family needs.
Hunger: It takes a lot of water to grow food and care for animals. Less water means farming and other crops that need water to grow have lower yield. It means farm animals will die and others will not do well without water. The result is constant hunger and thirst and low quality of life. Poverty: Access to quality water is a key to economic prosperity and better living standards. Lack of it will definitely go to affect adversely as people will be in constant poverty. Businesses and schools thrive when people come to work on time and not have to spend all morning looking for water. Restaurants, hotels and shopping places need to keep clean to attract tourists and foreign investments. Manufacturing activities, commercial farms, and mining processes all need a lot of water to flourish. 

Question. What do you know about the ‘Bamboo-Drip Irrigation System’?
Answer. In Meghalaya, a 200 year old system of tapping stream and spring water by using bamboo pipes, is prevalent.
- Bamboo pipes are used to divert perennial springs on the hilltops to the lower reaches by gravity.
- The channel sections made of bamboo, divert water to the plant site, where it is distributed into branches.
- If the pipes pass roads, they are taken high above the land on the tree branches.
- Reduced channel sections and diversion units are used at the last stage of water application.
The last channel section enables water to be dropped near the roots of the plant. 

Question. How does urbanization and urban lifestyle lead to over-exploitation of water?
Answer. Multiplying urban centres with large and dense population and urban lifestyles have not only added to water and energy requirements but have further aggravated the problem. Fragile water resources like groundwater are being overexploited and have caused their depletion in several cities.

Question. Highlight any three hydraulic structures as a part of water management programmes initiated
in ancient India.
Answer. l In the first century BC, Sringaverapura near Allahabad had sophisticated water harvestingsystem, channelling the flood water of river Ganga.
- During the time of Chandragupta Maurya, dams, lakes and irrigation systems were extensively built.
- Evidences of sophisticated irrigation works have also been found in Kalinga (Odisha), Nagarjun-Konda (Andhra Pradesh), Bennur (Karnataka) and Kolhapur (Maharashtra).
- In the 11th century, Bhopal Lake, one of the largest artificial lakes of its time, was built.
- In the 14th century, the tank in Hauz Khas, Delhi was constructed by Iltutmish for supplying water to Siri Fort area.

Question. Explain the ecological problems being faced due to multi-purpose river valley projects.
Answer. In recent years, the multipurpose projects and large dams have come under great scrutiny and opposition for a variety of reasons:
(i) Regulating and damming of rivers affect the natural flow of rivers, causing poor sediment flow and excessive sedimentation at the bottom of the reservoir, resulting in rockier streambeds and poorer habitats for the rivers’ aquatic life.
(ii) Adverse environmental effects in the form of water-logging, salinity have led to the degradation of soil. Cropping patterns of many regions have changed due to irrigation with farmers shifting to water intensive and commercial crops.
(iii) Dams also fragment rivers, making it difficult for the aquatic fauna to migrate, especially for spawning.
(iv) The reservoirs that are created on the floodplains also submerge the existing vegetation and soil leading to its decomposition over a period of time.

Question.Why is the practice of rooftop rainwater harvesting slowly declining in Rajasthan? Which state has made rooftop rainwater harvesting compulsory?
Answer. (i) In Rajasthan, sadly the practice of rooftop rainwater harvesting is on decline.
(ii) It is due to availability of plenty of water from Perennial Rajasthan Canal.
(iii) New generation considers stored water of rainwater unhygienic so they don’t prefer to drink that water.
(iv) Tamil Nadu is the state which has made rooftop rainwater harvesting compulsory. 

Question. ‘Rainwater harvesting system is viable alternative both ways socio-economically and environmentally.’ Support the statement with three examples.
Answer. Keeping into view the disadvantages and rising resistance against the multipurpose dams, water harvesting system is considered viable alternative both socio-economically and environmentally. For example, rooftop rainwater harvesting is the most common practice in Shillong, Meghalaya. Though this region receives the highest rainfall in the world, yet the state capital, Shillong faces acute shortage of water. Nearly every household in the city has a rooftop rainwater harvesting structure.

Question. “The dams that were constructed to control floods have triggered floods.” Analyse the statement. 
Answer. A dam is designed within engineering parameters. These include factors of safety for the earthworks or concrete arch which their construction effectiveness relies on. There are very careful calculations done during the design, to allow for all sorts of eventualities in the catchment area (the places where the upstrem water is collected from), also the floods that brought destruction 100 years ago. If the reservoir above the dam is susceptible to rockfall, engineers even alow for the effects of waves overtopping the dam. Even after all those calculations, the Engineer designer leaves a safety height below the dam crest as an additional amount of protection to avoid the dam failing by overtopping. Big dams are equipped also with spillways to help manage any such event.
When the water behind a dam reaches the capacity of the dam, water must be released the prevent damage to the dam. Sometimes extremely large amounts of water needs to be released during large rain. These large releases of water sometimes cause flooding downstream. When water in the dam reaches near to the maximum capacity, it needs to be released to prevent it from breaking. In certain situations when there are heavy rain and all more amount of water needs to be released from the dam which will cause for the increase of water in the river and flooding in the downstream of the dam. So that the people residing near to the river needs to be relocated.

 

NCERT Solutions for Class 10 Social Science Chapter 3 Water Resources Source-based Question

Read the source given below and answer the questions that follow:

Many thought that given the disadvantages and rising resistance against the multipurpose projects, water harvesting system was a viable alternative, both socio-economically and environmentally. In ancient India, along with the sophisticated hydraulic structures, there existed an extraordinary tradition of water-harvesting system. People had in-depth knowledge of rainfall regimes and soil types and developed wide ranging techniques to harvest rainwater, groundwater, river water and flood water in keeping with the local ecological conditions and their water needs. In hill and mountainous regions, people built diversion channels like the ‘guls’ or ‘kuls’ of the Western Himalayas for agriculture. ‘Rooftop rainwater harvesting’ was commonly practised to store drinking water, particularly in Rajasthan. In the flood plains of Bengal, people developed inundation channels to irrigate their fields. In arid and semiarid regions, agricultural fields were converted into rain fed storage structures that allowed the water to stand and moisten the soil like the ‘khadins’ in Jaisalmer and ‘Johads’ in other parts of Rajasthan.

Question. What were ‘guls or kuls’?
Answer. They were water diversion channels.

Question. Where is rooftop rainwater harvesting practices commonly?
Answer. It is practised most commonly in Rajasthan.

Question. India tracing the sophisticated hydraulic structures to which era?
Answer. India traces the sophisticated hydraulic structures to the ancient era.

Read the following passage and answer the questions at the end.

Multi-purpose projects and large dams have also been the cause of many new social movements like the 'Narmada Bachao Andolan' and the Tehri Dam Andolan' etc. Resistance to these projects has primarily been due to the large-scale displacement of local communities. Local people often had to give up their land, livelihood and their meagre access and control over resources for the greater good of the nation. So, if the local people are not benefiting from such projects then who is benefited? Perhaps, the landowners and large farmers, industrialists and few urban centres. Take the case of the landless in a village - does he really gain from such a project?

Question. What was the reason behind Narmada Bachao Andolan?
Answer. Displacement of local people on a large scale

Question. Who is benefited by multi-purpose projects?
Answer. Zamindars and big farmers or industrialists and some urban centers

Question. What is your opinion on resistance against large dam from local people. Write in your own words.
Answer. The government should compensate the displaced people and make them partners in profit sharing.