Water resources

The essentials

India has about 2.45 per cent of the world's surface area and about 4 per cent of its water resources, but a far larger share (roughly one-sixth or more) of its population. Water comes from precipitation and is available as surface water (rivers, lakes, ponds, tanks) and groundwater. Only a part of the total water is utilisable because of topographical, hydrological and other constraints.

River basins differ greatly: the Ganga, Brahmaputra and Barak systems carry a large share of the country's surface water, though much of it cannot be used. Groundwater use is very high in north-western states such as Punjab, Haryana and Rajasthan, and in Tamil Nadu, leading to falling water tables.

Key points

• Agriculture is the largest user of water in India, mainly for irrigation; industrial and domestic demand is rising with urbanisation.
• Causes of water scarcity: growing population, expanding irrigation, industrialisation, urbanisation, over-exploitation of groundwater and pollution.
• Water pollution from industrial effluents, domestic sewage and agricultural chemicals reduces usable water; the Ganga and Yamuna are among the most polluted rivers.
• Rainwater harvesting: capturing and storing rainwater for later use or to recharge groundwater; it is cheap, eco-friendly and raises the water table.
• Watershed management: efficient management and conservation of surface and groundwater in a watershed, including prevention of runoff, storage and recharge.
• Examples: Haryali (central government scheme for drinking, irrigation, fisheries and afforestation via watersheds), Neeru-Meeru (Water and You) in Andhra Pradesh, Arvary Pani Sansad in Alwar, Rajasthan, and the community-led work at Ralegan Siddhi in Maharashtra.

Exam tips

Match each watershed programme with its state; also be ready to give reasons why rainwater harvesting is useful.

Common mistakes

Groundwater is not unlimited; extraction faster than recharge lowers the water table even in areas with good rainfall.