(a) The advantages of constructing dams across the rivers are:

1. Water from a dam is used for irrigation in fields through a network of canals.
2. Water from a dam is supplied to the people in towns and cities through pipelines after suitable treatment.
3. The falling water from the dam is used for generating electricity.

(b) The problems associated with the construction of dams are:

1. Social Problems: Due to the constriction of high rise dams, a large number of human settlements are submerged in the water of large reservoir formed by the dam and many people are rendered homeless. This creates a social problem.
2. Environmental Problems: The construction of high rise dams on the rivers contributes to deforestation and loss of biodiversity. This is because of a vast variety of flora and fauna (plants and animals) get submerged in the water of large reservoir formed by the dam and disturb the ecological balance.
3. Economic Problems: Some people say that the construction of high rise dams involves the spending of huge amount of public money without the generation of proportionate benefits.