• The main source of water on earth is the hydrological cycle.
• India receives nearly 4% of the global precipitation to rank 133rd in the world in terms of water availability per person per annum.
• If water is not conserved, by 2025 a large part of India will face water scarcity.
• Water scarcity is caused by over-exploitation, excessive use of and unequal access to water among different social groups.
• In India, most of the energy required to run industries comes from hydroelectric power.
• The water around us needs to be conserved and managed to safeguard ourselves from health hazards, to ensure food security, continuation of our livelihoods and productive activities, and also to prevent degradation of our natural ecosystem.
• The multipurpose projects are meant to tackle various problems associated with river valleys in an integrated manner.
• They help to control flood, check soil erosion, provide water for irrigation and drinking purposes, generate electricity for industries, villages, cities, provide inland navigation, help in preservation of wildlife and development of fisheries.
• Dams
  • Damodar Valley Corporation — built on river Damodar — beneficiary states are Jharkhand and West Bengal.
  • Bhakra Nangal — built on river Sutlej — beneficiary states are Punjab, Haryana and Rajasthan, Himachal Pradesh
  •  Hirakud — built on river Mahanadi — beneficiary state is Orissa.
  • Kosi — built on river Kosi — beneficiary state is Bihar and our neighbouring country Nepal.
  • Chambal Valley — built on river Chambal — beneficiary states are Madhya Pradesh and Rajasthan.
  • The greatest example of integrated water management is the building of multipurpose river projects.

These include the dam which is built not just for irrigation and flood control but also for generation of hydroelectricity for industrial uses, recreation, inland navigation and fish breeding.

• Many such projects have caused environmental damages by inducing earthquakes, destroying natural habitats, causing water-borne diseases and water pollution.
• Rainwater harvesting is a technique of increasing the recharge of groundwater by capturing and storing rainwater by constructing wells, percolating pits and check dams.
• The main objectives of the rainwater harvesting are :
  • to meet the increasing demand of water.
  • to reduce runoff.
  • to avoid the flooding of roads