Water Resources Summary Class 10 Social Science Chapter 3

Water

• Water is a renewable resource
• Three-fourth of the earth’s surface is covered with water but only a small proportion of it accounts for freshwater fit for use.

Some facts and Figures

• 96.5 percent of the total volume of world’s water is estimated to exist as oceans and only 2.5 per cent as freshwater.
• India receives nearly 4 percent of the global precipitation and ranks 133 in the world in terms of water availability per person per annum.
• By 2025, it is predicted that large parts of India will join countries or regions having absolute water scarcity.

Water Scarcity and need for water conservation and management

• The lack sufficient water as compared to its demand in a region is known as Water Scarcity.
• Causes of Water Scarcity are:
  • over-exploitation
  • excessive use and unequal access to water among different social groups.
  • Large population

Dams

• A dam is a barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment.

Multi-Purpose River Projects

• Multi-purpose river projects large dams that serve several purposes in addition to impounding the water of a river and used later to irrigate agricultural fields. For example, the Sutluj-Beas river basin, the Bhakra–Nangal project etc.

Advantages of multi-purpose river projects are:

• Electricity generation
• Irrigation
• Water supply for domestic and industrial uses
• Flood control
• Recreation
• Inland navigation 
• Fish breeding

Disadvantages of Multi-purpose river projects are:

• It affects the natural flow of river causing poor sediment flow and excessive sedimentation at the bottom of the reservoir.
• It destroys the habitats for the rivers’ aquatic life.
• It submerges the existing vegetation and soil if created on the floodplains.
• It displaces the local people of the place where it is created.
• These are unsuccessful in controlling floods at the time of excessive rainfall.
• These projects induced earthquakes, caused water- borne diseases and pests and pollution resulting from excessive use of water.

Movements against Mult-purpose river projects

• These projects cause of many new social movements like the ‘Narmada Bachao Andolan’ and the ‘Tehri Dam Andolan’ etc.
  • This is due to the large-scale displacement of local communities.
• Inter-state water disputes are also becoming common with regard to sharing the costs and benefits of the multi-purpose project.

Rainwater Harvesting

• Rainwater Harvesting refers to the practice of storing and using of rainwater from the surface on which it falls.
• In hill and mountainous regions, people built diversion channels like the ‘guls’ or ‘kuls’ of the Western Himalayas for agriculture.
• In Rajasthan, ‘Rooftop rain water harvesting’ was commonly practised to store drinking water.
• In the flood plains of Bengal, people developed inundation channels to irrigate their fields. 
• 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.
• In the semi-arid and arid regions of Rajasthan, almost all the houses traditionally had underground tanks or tankas for storing drinking water.

How Tankas works:

• Tankas 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’.