CBSE Class 10 Science 2018 · Paper 31/1 · Question 15

Dam: a barrier built across a river or a stream to hold back its water and store it, forming a reservoir. We build large dams because they can store adequate water for irrigation and also for generating electricity; water from the reservoir is carried through canals to fields and is also supplied to towns and cities. The three main problems to be addressed: Social problems: large numbers of local people, mostly peasants and tribals, are displaced from their land and homes, and must get adequate compensation and rehabilitation. Economic problems: huge amounts of public money are spent without proportionate benefits. Environmental problems: large-scale deforestation and loss of biological diversity, as forests are submerged.