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Q.1. Analyse the impact of ‘water scarcity’. (CBSE Delhi 2019)
Ans. 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 arc not allowed to go to school at all so that they can serve the family by gelling 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.
Q.2. “The dams that were constructed to control floods have triggered floods.” Analyse the statement. [CBSE 2019, 32/2/1]
Ans. 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 upstream 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 allow 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.
Q.3. Explain any three reasons for which the multi-purpose projects and large dams have come under great scrutiny and opposition in the recent years. [CBSE2018]
Ans. (a) 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.
(b) Dams also fragment rivers making it difficult for aquatic fauna to migrate, especially for spawning.
(c) The reservoirs that are created on the floodplains also submerge the existing vegetation and soil leading to its decomposition over a period of time.
Q.4. Water scarcity in most cases is caused by over-exploitation, excessive use and unequal access to water among different social groups.” Explain the meaning of statement with the help of examples. [CBSE 2016-17]
Ans. The above statement is true as explained below :
(i) Over-exploitation : (a) Water resources are over-exploited to produce more food for more population.
(b) Farmers have tubewells in their farms for irrigation.
(c) Industries use water to have hydroelectric power to run them.
(ii) Excessive use : (a) Urban centres with large and dense populations and urban life styles use excess water for their requirements.
(b) Generally water is not recycled and is wasted indiscriminately in the cities.
(iii) Unequal access to water among different social groups : (a) Rich people have sufficient water for their use at homes as well as in factories.
(b) The poor do not get sufficient supply of water in their localities. They get water supply only for a fixed period of time.
Q.5. What is rainwater harvesting ?
How is rainwater harvesting carried out in semi-arid regions of Rajasthan ?Explain. [CBSE 2016-17]
Ans. (a) Rainwater harvesting is a technique of increasing the recharge of groundwater by capturing and storing rainwater by constructing structures, such as dugwells, percolation pits, checkdams.
(b) (i) 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.
(ii) In Bikaner, Phalodi and Banner, almost all the houses had underground tanks for storing drinking water.