Chapter 3 - Water Resources

Chapter - 3

Water Resources

Water
 97.5% of the water on Earth exists in oceans and seas.
About 2.5% of total water is available as freshwater.
70% of total freshwater is present as frozen ice in icebergs and glaciers. 

A little less than 30% of the total freshwater is stored as groundwater. 

Reasons for Water Scarcity
        Overexploitation
        Excessive use
        Unequal access
        A large population
        Large-scale farming
        Large-scale deforestation has disturbed the natural recharge of groundwater
        Construction of concrete buildings, factories and roads have also made the groundless impervious to rainwater. 

        This has almost totally stopped the percolation of rainwater to recharge groundwater.
 Excess use of chemical fertilizers and insecticides has contaminated groundwater at many places.  The contamination is at such a high level that water has become unfit for human consumption.
 Sewage and effluents are being discharged into rivers and ponds; without being treated. This has turned most of the rivers into filthy drains.
Water Resource Management
 India had a long tradition of building various structures to manage water resources.
 Irrigation systems were built as early as during the Mauryan Empire.
Advantages of Multi-Purpose River Valley Project
 At present, many multipurpose dam projects had been built in India.
 These dams serve many purposes.
 Prevent flood by checking the flow of water.
 Dams are used through a system of canals to irrigate far-flung areas.
 Dams are also used for electricity generation.
 Moreover, drinking water is also supplied from the dams.
Disadvantages of Multi-Purpose River Valley Project
 Dams have caused a lot of people being displaced from their ancestral lands.
 A vast tract of land gets submerged in the catchment area of the dam.
 This results in large-scale environmental consequences.
 Due to these reasons, many movement groups have begun protesting against the building of large dams.
 Narmada Bachao Andolan is an example of one such movement.
 Interstate disputes.
 Sedimentation Rainwater Harvesting
 Most of the rainwater just flows off without percolating down the ground.
 This can be prevented by using rainwater harvesting.
 Rainwater can be collected for future use or can be channelized to recharge groundwater.
 Rooftop harvesting - Mysore – Karnataka
 Guls Or kuls – Western Himalayas
 Inundation canals – flood plains of Bengal
 Khadins – Jaisalmer (Rajasthan) and Johads –Rajasthan Tankas – Rajasthan (Bikaner, Phalodi, and Barmer )
 Bamboo drip irrigation – Meghalaya