Short Notes and Video Lecture : Water Resources

 Facts and Figures

  • Out of total volume of water resources  on earth about  97.5% exists in oceans and seas.
  • About 2.5% of it exists   as freshwater.

  • 70% of total freshwater is present as frozen ice in icebergs and glaciers.
  • A little less than 30% of total freshwater is stored as groundwater.

  • India receives about 4% of global precipitation.
  • India ranks 133rd in the world in terms of water availability per person per annum. The total renewable water resources in India are estimated at 1,897 sq km per annum.

Scarcity of Water

  • Over exploitation , excessive use and unequal access to water among different social groups are the main causes for its scarcity.
  •  Large scale farming also needs lot of water for irrigation to feed the growing population .
  • Large scale deforestation has disturbed the natural recharge of groundwater at many places. Construction of concrete buildings, factories and roads has also made the ground less able to percolate   rainwater to recharge groundwater.

What is a Dam ?

A Dam is a barrier constructed to hold back waterflow and raise its level, forming a reservoir used to generate electricity or as a water supply.

Advantages of Dams

  • Provides clean source of Energy
  • Prevents Flooding
  • Helps in Proper Irrigation
  • Long term freshwater source

Disadvantages Of Dams

  • Huge costs and time involved
  • Tribal and local population need to be displaced .
  • Excessive sedimentation in rivers .
  • Prevent Migration of fishes
  • Loss of natural habitat and wildlife .

What is Rainwater Harvesting ?

  • Rainwater harvesting is a technique of collection and storage of rainwater into natural reservoirs or tanks .

Rooftop Rainwater Harvesting

In this technique rainwater is collected by the roof top or the roofs of houses or offices .

  • Roof top rain water is collected using a PVC pipe
  • Filtered using sand and bricks
  • Pipe takes water to sump for immediate usage or for storage .
  • Rainwater from the well recharges the underground or Take water from the well later .

Narmada Bachao Andolan

  • Narmada Bachao Andolan or Save Narmada Movement is a Non Governmental Organisation (NGO) that mobilised tribal people, farmers, environmentalists and human rights activists against the Sardar Sarovar Dam being built across the Narmada river in Gujarat.

  • It originally focused on the environmental issues related to trees that would be submerged under the dam .
  • Recently it has re-focused the aim to enable poor citizens, especially the oustees (displaced people) to get full rehabilitation facilities from the government.

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