Class Notes NCERT Solutions for CBSE Students
Question: How is freshwater obtained?
Answer: The freshwater is obtained from precipitation, surface run off and groundwater that is continually being renewed and recharged through the hydro-logical cycle.
Question: What is hydro-logical cycle?
Answer: The continuous movement of water on, above and below the surface of earth.
Question: What is the importance of hydro-logical cycle?
Answer: The freshwater is mainly obtained from surface run off and groundwater that is continually being renewed and recharged through the hydro-logical cycle. All water moves within the hydro-logical cycle ensuring that .water is renewable resource. .
Question: What is water scarcity?
Answer: Water scarcity is the lack of sufficient available water resources to meet the demand.
Question: “The availability of water resources varies over space and time”. Give reasons.
Answer: Water resources varies over space and time due to the variation in seasonal and annual precipitation.
Question: What percentage of the total volume of world’s water is estimated to exist as oceans?
Answer: 96.5%
Question: How much per cent of the total volume of world’s water is estimated to exist as fresh water?
Answer: 2.5
Question: What are the sources of fresh water?
Answer: Precipitation, surface run off and groundwater.
Question: How is freshwater being renewed?
Answer: The freshwater is being renewed through the hydro-logical cycle.
Question: Mention any two regions which are expected to face water shortage.
Answer:
- Regions having low rainfall
- Regions which are drought prone
Question: What is a dam?
Answer: ‘A dam’ is a barrier across the flowing water that obstructs dissects or retards the flow, often creating a reservoir, lake or impoundment.
Question: What is a multipurpose project?
Answer: A multipurpose project is that which fulfills a variety of purposes at the same time, for example – irrigation, generation of electricity, flood control, fish breeding, soil conservation etc.
Question: Who proclaimed dams as the temples of modem India?
Answer: Jawaharlal Nehru
Question: Why were the multipurpose river projects considered as temples of modern India by Jawaharlal Nehru?
Answer: These would integrate development of agriculture and the village economy with rapid industrialization and growth of the urban economy.
Question: Name any two social movements which have been launched against the multipurpose projects.
Answer: Narmada Bachao Andolan and ‘Tehri Dam’ Andolan.
Question: What was considered as a viable alternative to the multipurpose projects and why?
Answer: The. disadvantages and rising resistance against the multipurpose projects, has lead us to conclude that water harvesting system is a viable alternative, both socio-economically and environmentally.
Question: Irrigation has changed the cropping pattern of many regions with farmers shifting to water intensive and commercial crops”. Mention its ecological consequence.
Answer: Salinisation of the soil
Question: What was the primary reason for launching ‘Narmada Bachao Andolan’?
Answer: Narmada Bachao Andolan was launched due to the large scale displacement of local communities.
Question: What is silt?
Answer: A fine soil which is formed in flood plains.
Question: How people used to conserve or harvest water in hills and mountainous regions?
Answer: By building diversion channels like the ‘guts’ or ‘kuls’.
Question: How people used to harvest water in the flood plains of Bengal?
Answer: By building inundation channels to irrigate their fields.
Question: How people harvest water in the semi- arid and arid regions of Rajasthan?
Answer: By building underground tanks.
Question: Many people of arid and semi-arid regions construct under-ground rooms adjoining the water tanks. Give reason.
Answer: By beating the summer heat it would keep the room cool.
Question: Name two techniques of roof top rain water harvesting.
Answer:
- Recharge through hand pump
- Recharge through abandoned dug well
Question: Name any two states where roof top water harvesting is most common.
Answer: Meghalaya and Rajasthan.
Question: Define the term Tankas.
Answer: Tankas are the underground tanks for storing drinking water.
Question: Which is the purest form of natural water?
Answer: Rainwater
Question: What is Kul?
Answer: It is a circular village tank from which water is released and taken when required.
Question: Name any two states which are involved in Krishna-Godavari-dispute.
Answer: Karnataka and Andhra Pradesh.
Question: Name the river on which the Hirakud dam is located.
Answer: Mahanadi
