Class 12 Geography Chapter 4: Water Resources Notes
Water is a vital natural resource that supports life, agriculture, industries, and ecosystems. In India, the availability of water varies across regions due to climatic and geographical factors. The country relies on surface water (rivers, lakes, reservoirs) and groundwater for domestic, agricultural, and industrial use. Sustainable water management is essential to address issues like over-extraction, pollution, and uneven distribution. This chapter explores the sources, utilization, conservation methods, and challenges of water resources in India.
Introduction to Water Resources in India
Why is Water Important?
- Water is essential for life, agriculture, industries, and energy production.
- India has 4% of the world’s freshwater resources but supports 17.7% of the world’s population.
Water Availability in India
- Total Annual Water Availability: ~4,000 billion cubic meters (BCM).
- Usable Water: ~1,123 BCM (due to rainfall variations and geographical factors).
- Per Capita Availability (2021): ~1,500 cubic meters (decreasing due to population growth).
Surface Water and Groundwater Resources
A. Surface Water Resources
- Surface water includes rivers, lakes, ponds, and reservoirs.
- India has major river systems that provide irrigation, drinking water, and hydroelectric power.
Major River Basins in India
| River Basin | Major Rivers | Regions Covered |
|---|---|---|
| Himalayan Rivers | Ganga, Brahmaputra, Indus | North & Northeast India |
| Peninsular Rivers | Godavari, Krishna, Kaveri, Mahanadi | Central & South India |
| West-Flowing Rivers | Narmada, Tapi | Western India |
B. Groundwater Resources
- Groundwater is stored in aquifers beneath the Earth’s surface.
- India has the largest groundwater irrigation system in the world.
Groundwater Availability
- Total Groundwater Recharge (2021): ~433 BCM.
- States with High Groundwater Use: Punjab, Haryana, Uttar Pradesh, Rajasthan.
- Problems: Over-extraction leads to falling water tables and desertification.
Water Demand and Utilization in Different Sectors
Water Consumption by Sector
| Sector | Percentage of Water Use | Purpose |
|---|---|---|
| Agriculture | 85% | Irrigation of crops |
| Industries | 7% | Manufacturing, cooling, power generation |
| Domestic Use | 6% | Drinking, sanitation, household needs |
| Others | 2% | Recreation, environmental needs |
Water Usage in Agriculture
- Most of India’s water (85%) is used for irrigation.
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Types of Irrigation in India:
- Canal Irrigation (Punjab, Haryana).
- Wells and Tube Wells (U.P., Bihar, Maharashtra).
- Drip and Sprinkler Irrigation (Rajasthan, Gujarat – for water conservation).
Water Scarcity and Its Causes
What is Water Scarcity?
Water scarcity occurs when demand exceeds supply or water is not available due to pollution or mismanagement.
Causes of Water Scarcity
- Overpopulation and Increasing Demand → More water needed for agriculture, industry, and homes.
- Uneven Rainfall Distribution → Some regions get excessive rainfall, while others face droughts.
- Over-Extraction of Groundwater → Excess use leads to falling water tables (e.g., Punjab, Rajasthan).
- Deforestation and Climate Change → Reduces rainfall and increases droughts.
- Water Pollution → Rivers and lakes contaminated by industrial waste, sewage, and chemicals.
Water Conservation and Management
Why Conserve Water?
- Ensures availability for future generations.
- Reduces groundwater depletion.
- Prevents droughts and desertification.
Methods of Water Conservation
- Efficient Irrigation: Drip and sprinkler systems reduce water wastage.
- Rainwater Harvesting: Collecting rainwater for reuse.
- Desilting of Tanks and Canals: Cleaning reservoirs to improve storage capacity.
- Reuse and Recycling: Treating wastewater for irrigation and industry.
- Watershed Management: Managing entire river basins to prevent floods and soil erosion.
Multipurpose River Projects and Their Impact
What Are Multipurpose River Projects?
Large dam projects designed for irrigation, hydroelectricity, flood control, water supply, and recreation.
Major Multipurpose River Projects in India
| Project | River | Purpose | States Benefited |
|---|---|---|---|
| Bhakra Nangal Dam | Satluj | Hydroelectricity, Irrigation | Punjab, Haryana |
| Damodar Valley Project | Damodar | Flood Control, Power | Jharkhand, West Bengal |
| Sardar Sarovar Project | Narmada | Drinking Water, Irrigation | Gujarat, Rajasthan |
| Hirakud Dam | Mahanadi | Irrigation, Power | Odisha |
| Tehri Dam | Bhagirathi | Hydropower | Uttarakhand |
Advantages of Multipurpose Projects
- Provide irrigation water for agriculture.
- Generate hydroelectric power (green energy).
- Control floods in river basins.
- Supply drinking water to cities and industries.
Disadvantages of Multipurpose Projects
- Displacement of People (Villages submerged, causing social conflicts).
- Environmental Issues (Deforestation, loss of biodiversity).
- Water Disputes Between States (e.g., Cauvery water dispute between Karnataka and Tamil Nadu).
Rainwater Harvesting and Watershed Management
A. Rainwater Harvesting
- Rainwater Harvesting is the collection and storage of rainwater for later use.
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Methods:
- Rooftop rainwater collection.
- Recharge pits to replenish groundwater.
- Example: Tamil Nadu made rainwater harvesting mandatory in buildings.
B. Watershed Management
- Watershed: A land area that drains rainfall into a river or lake.
- Watershed Management: Conserving soil and water by planting trees, building small check dams, and preventing erosion.
- Example: The Sukhomajri Watershed Project (Haryana) improved water availability for farmers.
Conclusion
- India has abundant water resources, but mismanagement and overuse are causing scarcity.
- Surface water (rivers, lakes) and groundwater are both essential.
- Agriculture consumes 85% of India’s water resources, so irrigation efficiency is crucial.
- Water scarcity is increasing due to population growth, climate change, and pollution.
- Multipurpose river projects provide water and electricity but also cause displacement and environmental issues.
- Water conservation techniques like rainwater harvesting and watershed management are key to sustainability.