Geography: Water Resources

The One Thing

Water is a renewable but limited resource whose availability varies across regions and seasons. Sustainable water management requires efficient use, rainwater harvesting, pollution control and fair participation, while balancing the benefits of large development projects against their social and environmental costs.

Who and What

• Water scarcity: A situation in which water availability is insufficient to meet the needs of people, agriculture, industries and ecosystems. It may occur because of low rainfall, pollution, overuse, poor management or unequal distribution.
• Water conservation: The careful use, protection and management of water to reduce wastage and preserve supplies for the future.
• Multipurpose river valley project: A large dam and reservoir project designed to provide several benefits, including irrigation, hydroelectricity, flood control, drinking water supply, navigation and recreation.
• Dam: A barrier built across a river to store, regulate or divert water.
• Reservoir: A stored body of water, usually created behind a dam, for human and economic needs.
• Hydroelectricity: Electricity generated by using the force of flowing or falling water to turn turbines.
• Irrigation: The artificial supply of water to agricultural fields.
• Rainwater harvesting: The collection and storage of rainwater for later use, or the direction of rainwater into the ground to recharge aquifers.
• Groundwater recharge: The process by which water enters and replenishes underground water reserves.
• Watershed management: The planned conservation and use of soil and water within a drainage area.
• Sustainable water management: Using water to meet present needs without reducing its availability or quality for future generations.
• Inter-state water dispute: A disagreement between states over the sharing, control or use of water from a common river.
• Narmada Bachao Andolan: A movement that raised concerns about displacement, environmental damage and the social effects of large dam projects in the Narmada valley.
• Tankas: Underground tanks traditionally used in Rajasthan to store harvested rooftop rainwater.
• Rooftop rainwater harvesting sequence: Roof catchment, pipes or channels, filter, and then either a storage tank or recharge pit.
• Water-balance relationship:

Water available = rainfall and inflow − evaporation − runoff − human use.

Causes and Consequences

• Limited freshwater availability creates a fundamental constraint. Only a very small proportion of the total water on Earth is usable freshwater; most water is saline or locked in ice and glaciers. Consequently, freshwater must be conserved and managed carefully.

• Water scarcity is not caused only by low rainfall. Population growth, urbanisation and industrialisation increase demand for drinking water, sanitation, energy and production. Scarcity may also occur where rainfall is adequate if water is polluted, poorly managed or distributed unequally.

• Agriculture places major pressure on freshwater supplies. Intensive irrigation and the cultivation of water-intensive crops increase consumption, making efficient irrigation methods such as drip irrigation and sprinkler irrigation important for conservation.

• Large dams can support economic development. Multipurpose river valley projects can provide irrigation, drinking water, hydroelectric power, flood control, navigation and recreation. A dam stores or regulates river water in a reservoir for these uses.

• Large dams also produce social and environmental costs. Their construction may displace people, submerge fertile land, destroy forests and biodiversity, and contribute to sedimentation, waterlogging and salinisation. Conflicts may arise over the distribution of benefits and costs.

• The Narmada Bachao Andolan questioned the consequences of large dams. Its concerns focused on displacement, environmental damage and the social impact of projects in the Narmada valley. This demonstrates why multipurpose projects should be assessed beyond their economic benefits.

• Traditional and decentralised systems can improve local water security. Tanks, ponds, johads, khadins, rooftop collection structures and underground storage systems collect or conserve water locally. In Rajasthan, rooftop rainwater was traditionally stored in tankas.

• Rainwater harvesting can increase groundwater recharge. Water collected from a roof can pass through pipes or channels and a filter before entering a storage tank or recharge pit. Tamil Nadu made rainwater harvesting compulsory in many buildings, helping promote groundwater recharge and water conservation.

• Water conservation requires both technological and behavioural measures. Repairing leaking pipes, reusing treated wastewater, protecting wetlands and preventing pollution reduce wastage and preserve water quality. Responsible consumption is necessary alongside infrastructure.

• Watershed management reduces pressure on rivers and groundwater. Planned conservation of soil and water within a drainage area can improve water availability and support local communities.

• Fair management is necessary because water is shared. Governments, local communities and different states must participate in decisions about water use. Inter-state water disputes show the importance of equitable arrangements for common rivers.

• Sustainable development links present use with future security. Efficient irrigation, rainwater harvesting, pollution control and responsible development must ensure that meeting current needs does not reduce the quality or availability of water for future generations.

What Gets Asked

• Why can water scarcity occur even in regions with adequate rainfall?
• How do population growth, urbanisation, industrialisation, intensive agriculture and pollution contribute to water scarcity?
• What are the benefits and disadvantages of multipurpose river valley projects and large dams?
• Why did the Narmada Bachao Andolan raise concerns about large dam projects in the Narmada valley?
• How does rooftop rainwater harvesting work, and how did the policy in Tamil Nadu support groundwater recharge?
• Compare traditional systems such as tanks, ponds, johads, khadins and tankas with modern water-management approaches.
• Explain how drip irrigation, sprinkler irrigation, treated wastewater reuse, wetland protection and pollution prevention contribute to water conservation.
• Why must water management include local communities, governments and different states?