A Small Proportion of It Accounts for: Water Management in Class 10 NCERT

Understanding How a Small Proportion of It Accounts for Usable Water

India receives abundant rainfall, but only a small proportion of it accounts for usable freshwater due to factors like evaporation, pollution, and uneven distribution. Water exists in oceans, glaciers, groundwater, rivers, and lakes, but:

• About 97% of Earth's water is saline and unsuitable for drinking or irrigation.
• Only 3% is freshwater, and of that, nearly 70% is locked in glaciers and ice caps.
• Less than 1% of total water is easily accessible surface water.

This limited availability means efficient water management is essential, especially in India where agriculture depends heavily on irrigation.

Worked example: If India receives 4000 billion cubic meters (BCM) of rainfall annually, but only 4% is usable surface water, then usable water = $4000 \times 0.04 = 160$ BCM.

Role of Multi-Purpose River Projects in Water Conservation

Multi-purpose river projects build dams and reservoirs to manage water for various uses:

• Irrigation: Supports agriculture in drought-prone and arid areas.
• Hydropower: Generates electricity for homes and industries.
• Flood Control: Regulates river flow to prevent floods.
• Domestic & Industrial Use: Provides water supply for cities and factories.

Examples include the Bhakra-Nangal project and Hirakud dam. These projects integrate multiple water needs, improving water availability.

Comparison Table:

Jawaharlal Nehru called dams the 'temples of modern India' for linking agriculture and industry.

Environmental Challenges of Large Dams and Water Projects

While large dams provide many benefits, they also cause environmental issues:

• Disruption of Natural Flow: Alters river ecosystems and sediment transport.
• Sedimentation: Reduces reservoir capacity over time.
• Habitat Fragmentation: Affects aquatic and terrestrial wildlife.
• Submergence: Floods forests and villages, causing displacement.
• Waterborne Diseases: Stagnant water can increase disease spread.
• Soil Salinization: Excess irrigation can degrade soil quality.
• Seismic Activity: Large reservoirs may induce earthquakes.

These drawbacks highlight the need for balanced water management and exploring alternatives like rainwater harvesting.

Traditional and Modern Water Conservation Methods in India

India has a rich history of water conservation:

• Ancient Hydraulic Structures: Dams, reservoirs, canals built since Mauryan times.
• Examples: Kalinga dams, Nagarjunakonda tanks, Hauz Khas tank.

Modern initiatives complement these:

• Pradhan Mantri Krishi Sinchayee Yojana (PMKSY): Aims to provide protective irrigation and improve water use efficiency.
• Rainwater Harvesting: Collecting and storing rainwater to recharge groundwater.

Activity: Research one traditional dam or tank and its role in local water management.

Combining traditional wisdom with modern technology ensures sustainable water use.

Inter-State Water Disputes and Their Impact on Water Management

Water sharing between states often leads to disputes due to limited supply and competing demands.

• Example: Krishna-Godavari river dispute involving Maharashtra, Karnataka, Andhra Pradesh.
• Causes: Water diversion, allocation disagreements, and differing development priorities.

These conflicts affect agriculture, industry, and livelihoods.

Solution Approaches:

• Central government mediation.
• Water sharing agreements.
• Promoting efficient water use and conservation.

Understanding these disputes is crucial for Class 10 students studying social science and water resource management.