Geography Chapter 3: Water Resources

Water covers nearly 3/4th of the Earth’s surface.

  • 96.5% of the total water on Earth is in oceans.
  • 2.5% is freshwater that exists in rivers and glaciers.
  • India receives 4% of the world’s rainfall and it ranks 133 in terms of water availability per person in a year.

Reasons for Water Scarcity in India

  • Low rainfall
  • Unequal distribution of water resources
  • Increasing demands because of the rapidly rising population
  • Large scale industrialization
  • Increased requirement of irrigation owing to the continuous expansion of agriculture
  • Increasing urbanization
  • Bad quality of water due to discharge of industrial wastes and chemicals

Multi-Purpose River Valley Projects

  • These are those river valley projects that serve multiple purposes such as irrigation, hydroelectric power generation and drinking water supply.
  • Dams are built across rivers. These are big reservoirs that store river and rainwater that is used for generating hydroelectricity and for irrigation.

Major Multipurpose Projects of India

  • Bhakra Nangal Project on Sutluj river
  • Hirakud Project on river Mahanadi
  • Damodar Valley Project on Damodar river
  • Narmada Valley Project on Narmada river

Disadvantages of Multi-Purpose Projects

  • Regulating the flow of rivers results in poor sediment flow and excessive sedimentation at the bottom of the reservoir. This results in rockier stream beds that are not suitable for sustaining the aquatic life.
  • Dams control the flow of rivers, which creates difficulty for the aquatic animals to migrate.
  • Dams also submerge the nearby vegetation and habitats.
  • Multipurpose projects cause large scale displacement of people.
  • Extensive irrigation causes the salinisation of soil.
  • The sedimentation at the base of the reservoir causes floods in the event of heavy rainfall.

Narmada Bachao Andolan

  • A non-governmental organization (NGO).
  • Against the Sardar Sarovar Dam on Narmada river in Gujarat.
  • Its focus is on environmental imbalance created by the dam and also on the rehabilitation of the displaced people.
  • Mobilised tribes, farmers and environmentalists.
  • Ms. Medha Patkar is the leader of this NGO.

Rainwater Harvesting

  • The system of collecting and storing rainwater.
  • Prevalent and useful in water deficient regions such as Rajasthan and dry parts of Gujarat.

Uses

  • For recharging ground water
  • For domestic usage
  • For irrigating crops

Roof-Top Rainwater Harvesting

  • Rainwater is collected in underground tanks connected to the rooftop through pipes.
  • Rain falling on rooftops travels down the pipes to the tanks and is stored for future usage.
  • Also used for recharging hand pumps and tube wells.
  • Most common is the desert districts of Rajasthan.

Bamboo Drip Irrigation System

  • Practised in Meghalaya.
  • A 200-year old system.
  • Water from the streams is tapped using bamboo pipes and used for irrigating the roots of plants.
  • Long bamboo pipes are connected with each other to form a chain from the stream to the crops.
  • Water flows through the pipes and drops directly at the site of the plant.