Question: Explain how water becomes a renewable resource.
Answer: 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 hydro-logical cycle. All water moves within the hydro-logical cycle ensuring that water is a renewable resource.
Question: What is water scarcity and what are its main causes?
Answer: Water scarcity is the shortage of water but it is not only associated with regions having low rainfall or those that are drought prone. The availability of water resources varies over space and time, mainly due to the variations in seasonal and annual precipitation, but water scarcity in most cases is caused by over- exploitation, excessive use and unequal access to water among different social groups.
Question: Compare the advantages and disadvantages of multi-purpose river projects.
Answer: Regulating and damming of rivers affect their natural flow causing poor sediment flow and excessive sedimentation at the bottom of the reservoir, resulting in rockier stream beds and poorer habitats for the rivers’ aquatic life. Dams also fragment rivers making it difficult for aquatic fauna to migrate, especially for spawning. It has great ecological consequences like salinisation of the soil. At the same time, it has transformed the social landscape i.e. increasing the social gap between the richer landowners and the landless poor.
The dams that were constructed to control floods have triggered floods due to sedimentation in the reservoir. Moreover, the big dams have mostly been unsuccessful in controlling floods at the time of excessive rainfall.
It was also observed that the multi-purpose projects induced earthquakes, caused waterborne diseases and pests and pollution resulting from excessive use of water.
Question: 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 tanks for storing drinking water. The tanks could be as large as a big room. The tankas were part of the well-developed rooftop rain water 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. Rainwater, or palar pani, as commonly referred to in these parts, is considered the purest form of natural water. Many houses constructed underground rooms adjoining the ‘tanka’ to beat the summer heat as it would keep the room cool.
Question: Describe how modern adaptations of traditional rainwater harvesting methods are being carried out to conserve and store water.
Answer: Fortunately, in many parts of rural and urban India, rooftop rainwater harvesting is being successfully adapted to store and conserve water. In Gendathur, a remote backward village in Mysore, 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. Rainwater harvesting is once again being conserved through modern adaptation. Rainwater running down from the roofs is not fed into drains. Instead it is piped into underground reservoirs.
Question: How have the growing population, industrialisation and urbanisation led to water scarcity? Explain.
Explain any four reasons responsible for water scarcity in India.
How have industrialisation and urbanisation aggravated water scarcity in India?
Give three reasons for water scarcity in post independent India.
‘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.
- Growing population: Growing population is one of the basic factors which is responsible for the scarcity of water. Most of our cities are facing this problem due to overpopulation. A large population means more water not only for domestic use but also to produce more food.
- Commercialisation of agriculture: After the success of Green Revolution, our farmers are producing commercial crops. The commercial crops need more water and other inputs. Assured means of irrigation like tube wells and wells are responsible for the falling groundwater levels.
- Industrialisation: The post independent India witnessed intensive industrialisation and urbanisation. Today, large industrial houses are common in the form of industrial units of many MNCs (Multinational Corporations). The ever increasing number of industries has made matters worse by exerting pressure on the existing freshwater resources. Industries, apart from being heavy users of water, also require power to run them. Much of this energy comes from the hydroelectric power.
- Urbanisation: Urbanisation has also aggravated the problem of water scarcity. Most of our cities are overpopulated. Overpopulation leads to over- utilisation of the water resources, and also pollutes the existing resources.
Question: How do the multipurpose river projects affect the aquatic life ? Explain.
Explain the ecological problems being faced due to the multi-purpose river projects.
Answer: In recent years, the multi-purpose projects and large dams have come under great scrutiny and opposition for a variety of reasons:
- Regulating and damming of rivers affect their natural flow causing poor sediment flow and excessive sedimentation at the bottom of the reservoir, resulting in rockier stream beds and poorer habitats for the rivers, as well as the aquatic life.
- Dams also fragment rivers making it difficult for the aquatic fauna to migrate, especially for spawning.
- The reservoirs that are created on the flood. Plains also submerge the existing vegetation and soil leading to its decomposition over time.
- Irrigation has also changed the cropping pattern of many regions with farmers shifting to water intensive and commercial crops. This has great ecological consequences like salinisation of the soil.