Q.1. What is rainwater harvesting? Explain any two different methods of rainwater harvesting in different regions of India. [2010, 2011 (T-1)]
Ans. Rainwater harvesting is a system in which rain water is collected through various techniques and then collected water is used in many ways.
(i) Hill region - In hilly region people built diversion channels like the ‘‘guls’’ or ‘‘kuls’’ in the western Himalayas for agriculture. With these channel rainwater is used in meaningful ways.
(ii) Arid region - In Rajasthan almost all houses had underground tanks. These tanks were part of well developed rooftop rainwater harvesting system. They were connected to the sloping roof of the houses through a pipe. Rain falling on the rooftops would travel down the pipe and get stored in these underground ‘tankas’.
Q.2. What is a multipurpose river valley project? Give any four objectives of the multipurpose river valley project. [2010, 2011 (T-1)]
Ans. The multipurpose river valley project is a river project in which a dam is constructed on the river and stored water is then used in a number of for like irrigation, power generation etc.
Four objectives of multipurpose projects are :—
(i) To check floods by regulating flow of water.
(ii) To generate hydro power for our industries and homes.
(iii) To provide irrigation facilities. This helps in increasing agriculture productivity and bringing more area under cultivation.
(iv) To check soil Erosion.
Q.3. Discuss how rainwater harvesting in semi-arid regions of Rajasthan is carried out. [2010 (T-1)]
Ans. Rain water harvesting in semi-arid region of Rajasthan is carried out in the following ways :- 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 was stored in these underground ‘tankas’.
Q.4. Describe three traditional methods of rainwater harvesting practised in India. [2010, 2011 (T-1)]
Ans. In India traditionally rainwater harvesting is done in the following ways :—
(i) In hilly regions people built diversion channels like the guls or kuls for agriculture.
(ii) In Rajasthan rooftop rainwater harvesting is practised.
(iii) In Bengal people built inundation channels to irrigate their fields.
(iv) In arid and semi-arid regions people convert their agricultural fields into rainfed storage structures.
Q.5. Give three reasons for water scarcity in post-independence India [2010, 2011 (T-1)]
Ans. Three reasons for water scarcity in India are :–
(i) Post-independance India has witnessed intensive industrialisation and urbanisation which increased water demand.
(ii) Large urban centres with large and dense population and urban lifestyles have only added to water requirement.
(iii) Population explosion after independence led to overexploitation of underground water for irrigation.
Q.6. ‘Three-fourths of the earth’s surface is covered with water but there is still scarcity of water across the globe.’ Explain giving three reasons. [2010, 2011 (T-1)]
Ans. Water scarcity is due to the following causes :—
(i) Water availability varies over space and time mainly due to the variation in seasonal and annual precipitation.
(ii) Rapid urbanisation is another factor for water scarcity.
(iii) Rapid increase in population that demand more and more water.
(iv) Industrialisation is another cause, large industrial houses are using more and more water, they also require more water to generate electricity.
(v) Rising income levels also create more demand for water.
(vi) 96.5 per cent of the total volume of world’s water is estimated to exist as oceans and only 2.5 per cent as fresh water. Nearly 70 per cent of this freshwater occurs as ice sheets and glaciers, while a little less than 30 per cent is stored as groundwater in the world’s aquifers.
Q.7. How have industrialisation and urbanisation aggravated water scarcity in India? [2010, 2011 (T-1)]
Ans. Industrialisation and urbanisation have aggravated water scarcity in India in the following ways :
(i) Large industrial houses are exerting pressure on existing freshwater resources. Industries apart from being heavy user of water also require water power to run them.
(ii) Multiplying urban centre with large and dense population and urban lifestyles have not only added to water and energy requirement but further aggravated the problems. Water resources are being over-exploited.
Q.8. Why is the conservation and management of water resources important? Give any three reasons. [2010 (T-1)]
Why is there an urgent need to conserve and manage our water resources? Give three reasons. [2011 (T-1)]
Ans. The conservation and proper management of water is necessary because of following reasons:
(i) Growing population :- As population is growing its need for water is also growing, so it is necessary to properly manage the availability of water.
(ii) Increasing Urbanisation :- More and more people are moving to cities where need of water is growing. On the other hand, cities are overexploiting and polluting water resources, so there is need to conserve water.
(iii) Due to industrialisation also water is being overexploited. So, without proper conservation it would be difficult to survive.
Q.9. Explain any three disadvantages of multipurpose projects. [2010, 2011 (T-1)]
Ans. Three disadvantages of multipurpose projects are :-
(i) A large area is submerged with water causing destruction of wildlife and forests.
(ii) A large number of people living in the affected areas are displaced, so their rehabilitation remains a problem.
(iii) Aquatic life and natural course of rivers get affected. Multipurpose projects had to destruction of flora and fauna.
Q.10. Why are different water harvesting systems considered a viable alternative both socio - economically and environmentally in a country like India? [2010, 2011 (T-1)]
Ans. No single method can be applicable everywhere. It is true in case of rain water harvesting system too, as geographically there are different regions. Different regions have different methods.
(i) In Hilly region :- Through kuls or guls it is very easy to divert water for irrigation. It is a low cost method.
(ii) In Arid region :- Like in Rajasthan rainwater is collected on roofs, then piped into ground storage system. That method is also economical, needing no extra effort.
(iii) In villages agricultural fields are converted into ponds where rainwater is collected. All these methods are very easy and viable.
Q.11. How far have the multipurpose projects been able to achieve their purpose for which they were made? Explain. [2010 (T-1)]
Ans. To some extent multipurpose river valley projects have been able to achieve their purpose. Irrigation has increased, power generation is a classic example of their success. But there are some concerns too.
(i) They have obstructed the natural flow of rivers causing destruction of habitat aquatic life.
(ii) People have also been affected as their habitat too have been submerged. It leads to socioeconomic proplems of big magnitude as lakhs of people are displaced.
(iii) This has led to huge destruction of flora and fauna, forests and biodiversity.
Q.12. Why is the need for water increasing day by day? Explain three reasons. [2011 (T-1)]
(i) Rapid industrialisation and urbanization have led to greater demand for water. Industries need water for various purposes.
(ii) Large population means more water is needed for domestic use and for agriculture to produce more food.
(iii) Multiplying urban centres with large and dense population and urban life-styles have led to greater need for water.
Q.13. Give an account of any three hydraulic structures of ancient India. [2011 (T-1)]
(i) During the period of Chandragupta Maurya - dams, lakes and irrigation systems were extensively built.
(ii) In the 11th century, Bhopal lake, one of the largest artificial lakes of its time was built.
(iii) In the first century B.C. Sringaverpur near Allahabad had large and complex water harvesting system chenneling the water of the Ganga.
Q.14. ‘Large multi-purpose projects also lead to land degradation.’ Explain. [2011 (T-1)]
Ans. Regulating and damaging of rivers affect their natural flow causing poor sediment flow and excessive sedimentation at the bottom of reservoir. Large reservoirs submerge large tracts of forests, flora and fauna. They also submerge soil leading to its decomposition over a period of time.