Page 44 - SST Class 04

The important canals in India :
u Indira Gandhi Canal u Upper Ganga Canal

u Lower Ganga Canal u Western Yamuna Canal
u Upper Bari Doab u Agra Canal
u Sharda Canal u Sirhind Canal

u Bhakra Canal etc.

4. Dams : A dam is a wall built across a river to regulate the flow of water. It creates a
large reservoir or lake of water. This water is used for two main purposes : irrigation

and generation of electricity. So, a dam is also called a multipurpose river project .
For irrigation, canals are dug from the dam to different areas. For generation of
electricity, water is allowed to fall from a great height on to the generators which
rotates them. Electricity is produced from these rotating generators. This type of

electricity is called hydroelectricity .
Important multipurpose river projects in India :

u Bhakra Nangal Project u Hirakud Project
u Kosi Project u Rihand Project

u Nagarjun Sagar u Beas Project
u Farakka Project u Damodar Valley Project

u Chambal Project u Gandak Project
u Tungabhadra Project etc.

Building a dam has some demerits. A dam is built over a

large area of land, for which, a large number of people
are shifted from their native place. Some
environmentalists think that these dams are not good for
the environment. If there is caused a crack in the dam, it
can inundate a large area in water. Because of these
causes, construction of many dams has faced opposition
from people. People opposed dams like the Tehri Dam
in Uttarakhand and the Sardar Sarovar Dam in Gujarat.
But these dams are necessary to meet needs of water and
Bhakra Nangal Dam
electricity.

Conservation of Water

We need water for different purposes. When we use it, it becomes dirty. As there is a
limited quantity of water on the earth, we have to be careful. If we used it
indiscriminately, it would be difficult to have clean water for use in the future. There is

44 Contemporary Social Science-4