NCERT Notes Class 10 Social Science Geography Chapter 3 Water Resources
Water Resources Study Notes, Questions and Answers / NCERT CBSE Notes Class 10 Geography Chapter 03 Water Resources
* Introduction:
Though Earth is covered with three-fourth of water, a tiny percentage of water is only usable and accessible. These are majorly the surface run-off and groundwater that are renewed by the hydrological process. Still, Water scarcity is an unresolved problem.
* Causes of Water Scarcity
● Irregular Precipitation - The seasonal and annual rainfall varies with geographical region and time.
● Over Exploitation of water - Due to the unequal access to water resources and increasing population, the water resources are overly exploited for domestic purposes, industrial needs. Meanwhile, it is polluted significantly due to hazardous practices by industries.
● Irrigative agricultural fields- Water is consumed in a large quantity for producing food. In a situation where every farmer owns individual water pumps,
the groundwater level decreases rapidly in that region, causing scarcity and drought. In dry areas, the intensity of drought further increases, thereby
increasing the need for the resource.
● Industries - Apart from harming and polluting the water resources like rivers and lakes, they also consume a considerable portion of groundwater by using their own water pumping devices. Also, the electric power supply for both industrial producers and Multinational Companies (MNCs) is from Hydroelectric power.
● Releasing untreated chemicals into water bodies. Unplanned drainage system. Throwing of garbage in water bodies.
* Solutions for Water Scarcity
Dams:
The dam is a hydraulic structure built to impound water for future use. This reservoir or impoundment essentially directs or retards the flow of water. It acts as a barrier for restricting the flow of water which can be later used for purposes such as irrigation, domestic use, industrial use, aquaculture etc.
Uses:
● Irrigation
● Electricity Generation
● Water supply for domestic purposes. Especially during droughts.
● Supply of water for industries and manufacturers.
● Flood control
● Recreational purposes
● Inland Navigation
● Fish Breeding.
Examples:
● In the Sutlej-Beas River Basin, The Bhakra-Nangal project has facilitated both hydel power production and irrigation.
● The Hirakud Project in the Mahanadi basin is for flood control. Dams are now considered multi-purpose projects, as they integrate many uses. After the independence of India, Jawaharlal Nehru proclaimed dams to "Temples of
Modern India '' as they would help in agriculture, development of village economy, blooming of industries, and growth of the urban economy.
* Undesirable Features of Dams
● Construction of Dam interrupted the flow of water and thus the irregular flow of sediments, increasing the sedimentation in the reservoir, which makes the
livelihood of aquatic animals difficult. The dam has fragmented rivers making the migration of aquatic organisms difficult especially for spawning.
● The Reservoirs created on the floodplains submerge the vegetation initiating decomposition of the same.
● Local People are getting displaced from their land, and they sacrifice their lives and resources for the Nation. But the Nation does not keep up with the
promises. Instead, the landlords are getting benefitted from dams.
● Due to high access to water, all farmers prefer commercial crops, and this causes an ecological imbalance, and also soil gets salinized.
● Increase in the social gap. The dams have caused disputes among people wanting their water needs to get prioritized. Even inter-state disputes have
become common.
● Ironically, flood control dams have triggered floods too. This is because of sedimentation in the reservoir. At the time of excessive rainfall, dams fail to control floods. The release of water from dams has aggravated the flood a lot of times.
● Land degradation- Apart from the loss of lives and properties, the flood also erodes soil. Sedimentation also means flood plains are deprived of silt, a natural
fertilizer.
● Others: induce earthquakes, cause water-borne diseases and pests.
* Rainwater Harvesting
Rainwater harvesting is based on region and climatic conditions. It has been in practice in India since ancient times.
● Western Himalayas - 'guls' or 'kuls' were diversion channels for water for agriculture.
● Rajasthan - Rooftop Rainwater harvesting. Recently Perennial Indira Gandhi canal.
● West Bengal - Inundation channels for irrigation.
● Arid and Semi-arid regions - Agricultural fields were used as rain-fed storage structures that enabled the rainwater to be stagnant and make the soil moist.
They store large tanks called tanks which are as big as a room and are placed in the courtyard of their house, the rainwater from their sloppy roofs would drip in the tanks through a pipe.
* Important Questions and Answers
1. Why water is a renewable resource?
Answer: Any resource that can replenish itself at a rate faster than or equal to the rate of usage is called renewable. Water continuously evaporates and collects in the atmosphere. It comes back to the surface in the form of rain. Since water is renewed by the natural hydrological cycle, thus it is called a renewable resource.
2. Why should water resources be conserved?
Answer: Repeated depletion of water may cause inadequacy for human needs and also cause environmental problems. Thus it is conserved and managed to safeguard ourselves from health hazards due to water pollution, to ensure food security and several other needs, and also to prevent degradation of our natural ecosystems.
3. What are the reasons for water Scarcity?
Answer:
i. Quantity based:
● Irregular Precipitation
● Over Exploitation of water and Unequal access
● Excessive usage by Irrigative agricultural fields
● Industrial excess usage.
ii. Quality based:
● Releasing untreated chemicals into water bodies. Unplanned drainage system. Throwing of garbage in water bodies.
4. Name some movements against Multi-purpose projects and state their reason.
Answer: Narmada Bachao Andolan' and 'Tehri Dam Andolan' were the environmental movements against Multipurpose projects mainly by the displaced locals as they lost their livelihood and no concession was provided.
5. List two ways to reduce water pollution.
Answer:
● Chemicals have to be treated before releasing them into water bodies.
● Garbage and drainage should not be disposed of in rivers and lakes.
6. What is Salinisation?
Answer: The process of increase in salt content in soil is called salinisation. Salts occur naturally within soils and water. Salination can be caused by natural processes such as mineral weathering or by the gradual withdrawal of an ocean.
7. List some Hydraulic structures.
Answer:
Dams: Dams refer to a barrier constructed across flowing water that restricts the flow to form a reservoir. This store water can be used for various purposes such as electricity generation and irrigation. Dams also play a
role in flood control.
Reservoirs or lakes: Reservoirs (man-made) and lakes (natural) store surface water. These are used for purposes such as boating, fishing and other recreational activities.
Embankments: Embankment refers to a thick wall or raised structure that is built to hold backwater. It is a traditional method of preventing flooding.
Canals: Canals are artificial waterways used to transport boats and ships. They also help with irrigation.
8. What is the solution for avoiding excessive water for irrigation?
Answer: Adoption of water-conserving techniques of irrigation, such as drip irrigation and sprinklers can help avoid the use of excessive water for irrigation. Other techniques like drought-resistant crops and dry farming which involve the cultivation of crops without irrigation have to be implemented and enforced on farmers. This involves the storage of moisture in the soil and selecting crops that would best utilize this moisture.
* TextBook Exercise Page No 46
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) A region with high annual rainfall.
(b) A region having high annual rainfall and large population.
(c) A region having high annual rainfall but water is highly polluted.
(d) A region having low rainfall and low population.
Answer:
(a) A region with high annual rainfall – Not suffering from water scarcity
(b) A region having high annual rainfall and large population – Suffering from water scarcity
(c) A region having high annual rainfall but water is highly polluted – Suffering from water scarcity
(d) A 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 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 the proper utilisation of water resources.
(b) Regulating and damming 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 practise of rooftop rainwater water 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 lifestyles have resulted in improper utilisation of water resources.
(b) Regulating and damming rivers does affect the river’s natural flow and its sediment flow.
(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 water harvesting popularity has declined due to high water availability from Indira Gandhi Canal.
2. Answer the following questions in about 30 words.
(i) Explain how water becomes a renewable resource.
Answer:
Water can be considered as a renewable resource since there will be rains and surface water and groundwater will get recharged continuously due to the 3 process involved in the hydrological cycle.
The 3 processes of the hydrological cycle are
Evaporations
Condensation
Precipitation
(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 a 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-exploited to expand irrigated areas for dry-season agriculture. Irrigated agriculture is the largest consumer of water. Most farmers have their own wells and tube wells in their farms for irrigation to increase their productivity. This has adversely affected the water availability and food security of the people.
(iii) Compare the advantages and disadvantages of multi-purpose river projects.
Answer:
Advantages:
Irrigation
Electricity generation
Flood control
Water supply for industrial and domestic purposes.
Tourist attraction
Inland navigation
Disadvantages:
The natural flow of water is affected
Aquatic life gets affected
Submergence of land in the surrounding areas
Ecological consequences
Large scale displacement of local people.
3. Answer the following questions in about 120 words.
(i) Discuss how rainwater harvesting in semi-arid regions of Rajasthan is carried out.
Answer:
In the semi-arid and arid regions of Rajasthan, particularly in Bikaner, Phalodi and Barmer, 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 be 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. Rainwater, or ‘palar pani’, as commonly referred to 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:
Water harvesting system is 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 floodwater 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 semi-arid 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. In Gendathur, a remote backward village in Mysuru, Karnataka, villagers have installed, in their household’s rooftop, rainwater harvesting system to meet their water needs. Nearly 200 households have installed this system and the village has earned the rare distinction of being rich in rainwater. Rooftop rainwater harvesting is the most common practice in Shillong, Meghalaya. It is interesting because Cherapunjee and Mawsynram situated at a distance of 55 km. from Shillong receive the highest rainfall in the world. Yet, the state capital Shillong faces an acute shortage of water. Nearly every household in the city has a rooftop rainwater harvesting structure. Nearly 15-25 per cent of the total water requirement of the household comes from rooftop water harvesting. Tamil Nadu is the first state in India that has made the rooftop rainwater harvesting structure compulsory to all the houses across the state.
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