Chapter 3 : Water Resources

Importance of Water

Key Points:

• Water is essential for drinking, cooking, washing, and industrial processes, including cooling machines.
• Hydel power plants generate electricity using water, highlighting its role in energy production.
• Historically, humans settled near water sources like rivers, springs, lakes, and oases for survival.
• Three-fourths of the Earth's surface is covered with water, but only a small proportion is usable freshwater.

Hydrological Cycle

Key Points:

• Freshwater is obtained from surface runoff and groundwater, recharged through the hydrological cycle.
• The hydrological cycle ensures water is a renewable resource as it moves through evaporation, condensation, and precipitation.

Water Scarcity

Causes of Water Scarcity:

• Over-exploitation: Excessive use of water for agriculture and industry depletes resources.
• Unequal Access: Disparities among social groups lead to water shortages in certain communities.
• Population Growth: Large populations increase demand for water for domestic and food production needs.
• Pollution: Contamination from domestic, industrial, and agricultural waste makes water unusable.
• Seasonal Variations: Variations in precipitation cause scarcity in low-rainfall or drought-prone areas.

Examples:

• Cities with ample water resources face scarcity due to high demand and pollution.
• By 2025, nearly two billion people may live in absolute water scarcity.

Water Conservation and Management

Initiatives:

• Atal Bhujal Yojana (Atal Jal): Implemented in water-stressed areas of seven Indian states to promote conservation and smart water management.
• Jal Jeevan Mission (JJM): Aims to provide potable piped water to every rural household, ensuring 55 liters per capita per day.

Need for Conservation:

• Protects against health hazards, ensures food security, and sustains livelihoods.
• Prevents ecosystem degradation and ecological crises due to over-exploitation.

Multi-purpose River Projects

Definition and Purpose:

• Dams are barriers that create reservoirs for irrigation, electricity, flood control, domestic/industrial water supply, navigation, and fish breeding.
• Examples: Bhakra Nangal (Sutluj-Beas) and Hirakud (Mahanadi) projects.

Advantages:

• Provide water to water-scarce areas and control floods.
• Generate electricity and support irrigation for agriculture.

Disadvantages:

• Environmental Impact: Alters river flow, reduces sediment, and affects aquatic habitats.
• Social Impact: Causes displacement and loss of livelihoods.
• Other Issues: Triggers floods due to sedimentation, induces earthquakes, and causes water-borne diseases.

Example:

• Sardar Sarovar Dam: Built on the Narmada River, it irrigates drought-prone areas in Gujarat, Rajasthan, and Maharashtra.

Traditional Hydraulic Structures

Historical Examples:

• Sringaverapura (1st Century B.C.): Sophisticated water harvesting system channeling Ganga floodwater.
• Chandragupta Maurya Era: Extensive dam and irrigation systems.
• Bhopal Lake (11th Century): One of the largest artificial lakes of its time.
• Hauz Khas Tank (14th Century): Built by Iltutmish in Delhi.

Rainwater Harvesting

Traditional Methods:

• Rajasthan Tankas: Underground tanks store rooftop rainwater, considered the purest form (palar pani).
• Western Himalayas: Diversion channels like 'guls' or 'kuls' for agriculture.
• Bengal: Inundation channels for field irrigation.
• Jaisalmer: Khadins and Johads as rain-fed storage structures.

Modern Adaptations:

• Gendathur, Karnataka: 200 households use rooftop rainwater harvesting, collecting 50,000 liters annually per house.
• Shillong, Meghalaya: 15-25% of household water comes from rooftop harvesting despite high rainfall nearby.
• Tamil Nadu: Mandatory rooftop rainwater harvesting for all houses.

Bamboo Drip Irrigation System

Key Features:

• 200-year-old system in Meghalaya using bamboo pipes to transport water from springs to plants.
• Delivers 20-80 drops per minute to plant roots, covering hundreds of meters.
• Gravity-based, with pipes adjusted to control water flow.

Flood Safety Precautions

Before Floods:

• Monitor weather bulletins and prepare an emergency kit (radio, medicines, dry food, etc.).
• Secure valuables and important documents.
• Move to safe areas like relief camps during floods.

During Floods:

• Avoid floodwaters, sewer lines, and fallen power lines.
• Use boiled water, eat covered food, and disinfect surroundings to prevent diseases.

Inter-state Water Disputes

Example:

• Krishna-Godavari Dispute: Karnataka and Andhra Pradesh object to Maharashtra diverting water at Koyna, affecting downstream agriculture and industry.