Water Resources

The One Thing

India possesses substantial water resources, but their availability is uneven across regions and seasons, while population growth, urbanisation, industrialisation, intensive agriculture and pollution are increasing water stress. Long-term water security therefore depends on conservation, efficient use, pollution control, rainwater harvesting, watershed development and participation by communities and institutions.

Who and What

• Water Resources: Surface water and groundwater available for human use, ecosystems and economic activities. India’s major sources include precipitation, rivers, lakes, reservoirs, tanks, ponds and groundwater.
• Surface Water: Water found in rivers, lakes, reservoirs, ponds, canals and other water bodies.
• Groundwater: Water stored below the ground in soil and rock layers, usually recharged by rainfall and seepage. It is important for irrigation and drinking water, but excessive withdrawal can lower the water table and cause wells to dry up.
• Water Scarcity: A condition in which demand exceeds available supply, or available water is unsuitable for use.
• Water Stress: Pressure on water resources resulting from high demand, limited availability, unequal distribution or declining quality.
• Irrigation: The artificial supply of water to agricultural land. It is essential because rainfall is seasonal, uncertain and unevenly distributed, and because multiple cropping requires an assured water supply.
• Multipurpose River Valley Project: A large project using river water for several purposes, including irrigation, hydroelectricity, flood control, water supply and navigation.
• Hydroelectricity: Electricity generated from the energy of flowing or falling water.
• Rainwater Harvesting: The collection and storage of rainwater from rooftops or land surfaces for later use or groundwater recharge.
• Watershed Management: The planned conservation and use of land, water and vegetation within a drainage basin.
• Water Conservation: The protection, careful use, recycling and efficient management of water resources.
• Inter-State Water Dispute: A conflict between states over the sharing, control or use of river water.
• Drought: A prolonged period of unusually low rainfall causing water shortages and affecting agriculture, ecosystems and livelihoods.
• Water Pollution: Contamination by sewage, industrial waste, agricultural chemicals, plastics or other harmful substances.
• Himalayan rivers: Generally perennial rivers because they receive water from rainfall as well as melting snow and glaciers.
• Peninsular rivers: Mainly seasonal rivers whose flow depends largely on the southwest monsoon.
• Coastal rivers: A commonly recognised category of India’s river systems alongside Himalayan and Peninsular rivers.
• Traditional water-harvesting systems: These include tankas in Rajasthan, khadins in western Rajasthan, johads in parts of Rajasthan and tank irrigation in several southern states.
• Major irrigation methods: Wells, tube wells, canals and tanks.
• Major multipurpose projects: Bhakra-Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar, Tehri and Sardar Sarovar.
• Water-balance relationship:

Water availability = precipitation + inflow − evaporation − outflow.

• Per capita water availability:

Per capita water availability = Total available water resources ÷ Population.

• Water-stress benchmark: A region is commonly considered water-stressed when annual per capita water availability falls below about 1,700 cubic metres.
• Water-scarcity benchmark: A region is commonly considered water-scarce when annual per capita water availability falls below about 1,000 cubic metres.

Causes and Consequences

• Uneven rainfall and seasonal river flow create regional differences in water availability. The southwest monsoon provides most of India’s annual rainfall, but rainfall is highly uneven in space and time. Himalayan rivers are generally perennial, whereas many Peninsular rivers are mainly seasonal.

• Seasonal, uncertain and uneven rainfall makes irrigation necessary. Irrigation supports food security, agricultural productivity and multiple cropping through wells, tube wells, canals and tanks.

• Agricultural demand contributes substantially to water stress. Water-intensive crops such as rice and sugarcane can intensify pressure when grown in unsuitable climatic regions.

• Excessive irrigation creates environmental and agricultural problems. It may cause waterlogging, soil salinity and groundwater depletion.

• Groundwater supports both irrigation and drinking-water supplies, but over-extraction lowers the water table. As a result, wells may dry up and local water availability may decline.

• Urban water demand rises with population growth, higher living standards, commercial activity and industrial development. This increases pressure on surface water and groundwater resources.

• Industrialisation and domestic activity increase water consumption and pollution. Water pollution reduces the amount of usable water and may cause diseases, eutrophication, fish death and ecological damage.

• Large dams and multipurpose projects provide important economic benefits. Projects such as Bhakra-Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar, Tehri and Sardar Sarovar can provide irrigation, hydroelectric power, flood control, drinking water, industrial water and inland navigation.

• Large multipurpose projects also impose social and environmental costs. These include displacement of people, submergence of forests and farmland, loss of biodiversity, sedimentation, changes in river ecosystems and conflicts over water sharing. Their construction and operation therefore require assessment and management of these consequences.

• Water scarcity reflects more than total quantity. Unequal distribution, seasonal availability, declining quality and unequal access can produce local and regional shortages even where national water resources are substantial.

• Rainwater harvesting reduces pressure on conventional supplies. It can reduce dependence on external water supplies, control runoff, improve groundwater recharge and help manage urban flooding.

• Watershed development supports local water security. By conserving land, water and vegetation within a drainage basin, it can recharge groundwater and strengthen rural livelihoods.

• Demand-side management is as important as increasing supply. Drip irrigation, sprinkler irrigation, wastewater treatment, recycling, leakage control and crop diversification reduce wastage and improve efficiency.

• Ecosystem-based measures contribute to conservation. Afforestation, recharge structures and protection of wetlands help regulate water systems and maintain ecological functions.

• Sustainable management requires coordinated participation. Central and state governments, local bodies, farmers, industries and households must cooperate through equity, efficiency, sustainability, integrated river-basin planning and participation of local communities.

• Water should be treated as a shared natural resource. Development planning must balance economic benefits with river-ecosystem protection and the rights of affected communities.

What Gets Asked

• Explain why India has substantial water resources but still experiences water scarcity and water stress.
• Compare Himalayan rivers and Peninsular rivers in terms of their sources, seasonality and significance.
• Explain why irrigation is necessary in India and evaluate the effects of excessive irrigation.
• Assess the economic benefits and social and environmental costs of multipurpose projects, referring to Bhakra-Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar, Tehri and Sardar Sarovar.
• Explain the importance of rainwater harvesting, including tankas, khadins, johads and tank irrigation, and relate these systems to groundwater recharge and runoff control.
• Discuss how pollution, urbanisation, industrialisation and intensive agriculture affect water security, and evaluate conservation measures such as drip irrigation, sprinkler irrigation, wastewater treatment, recycling, leakage control, crop diversification, afforestation, recharge structures and wetland protection.