Around 75% of the Earth's surface is enveloped by water, but only a tiny fraction of this water is suitable and within our reach. This mainly includes water that flows on the surface and is stored underground, which can be replenished through natural water processes. However, the problem of insufficient water supply continues to exist.
Sources of Water
- 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.
Note: If water is not conserved, by 2025 a large part of India will face water scarcity.
Causes of Water Scarcity
(1) Overuse of water
(2) Pollution of water
Water Resources and Management
- 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.
Question for Key Concepts: Water Resources
Try yourself: What is the main source of water on Earth?
- The main source of water on Earth is the hydrological cycle, which involves the continuous movement of water between the atmosphere, land, and oceans.
- This cycle begins with the evaporation of water from the surface of the oceans, lakes, and rivers, which forms clouds in the atmosphere.
- These clouds then condense and precipitate as rainfall, snow, or hail, which replenishes the water on the Earth's surface.
- Rainfall is therefore the primary source of freshwater that is suitable for human use.
- Other sources of water, such as ocean water, underground water, and glacier meltwater, may not be readily accessible or suitable for consumption without proper treatment.
Note: The solution explains that the main source of water on Earth is the hydrological cycle, which involves the continuous movement of water between the atmosphere, land, and oceans. It further states that rainfall is the primary source of freshwater suitable for human use.
Multi-Purpose River Projects
- 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.
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.
- To augment the groundwater storage and raise the water table.
- To reduce groundwater pollution.
- To improve the quality of groundwater.
- To supplement domestic water requirement during summer and long dry spells.
- Many thought that given the disadvantages and rising resistance against the multipurpose projects, water harvesting system was a viable alternative, both socio-economically and environmentally.
- People had in-depth knowledge of rainfall regimes and soil types and developed wide ranging techniques to harvest rainwater, groundwater, river water and floodwater in keeping with the local ecological conditions and their water needs.
- Rooftop rainwater harvesting has been done in Rajasthan, Meghalaya, Karnataka and Tamil Nadu on a regular and vast basis.