Introduction

Water is one of the most essential natural resources for life. It is required for drinking, agriculture, industries, electricity generation, and maintaining ecological balance. Even though Earth has a lot of water, only a small portion is usable freshwater.

Water Availability on Earth

About 71% of Earth’s surface is covered with water, but most of it is saline (saltwater) found in oceans and seas.

• 97.5% saltwater (oceans)
• 2.5% freshwater
• Less than 1% is easily available for human use

Importance of Water

• Essential for human survival.
• Used in agriculture (irrigation).
• Used in industries.
• Generates hydroelectric power.
• Maintains ecological balance.

Sources of Water

1. Surface Water

• Rivers, lakes, ponds, reservoirs.

2. Groundwater

• Water stored below Earth’s surface.

3. Rainwater

• Main source of freshwater replenishment.

Water Scarcity

Water scarcity means shortage of water resources compared to demand.

Main Causes of Water Scarcity

• Population growth.
• Overuse of water in agriculture.
• Industrial expansion.
• Unequal distribution of water.
• Pollution of water sources.

NCERT Insight

Multi-purpose River Projects

Multi-purpose river projects are large dams built across rivers to serve multiple functions such as irrigation, electricity generation, flood control, and water supply.

Main Objectives

• Generate hydroelectric power.
• Provide water for irrigation.
• Control floods.
• Supply water for domestic and industrial use.

Dams in India

Dams are barriers built across rivers to store water. India has many major dams which play an important role in water management and power generation.

Important Dams

• Bhakra Nangal Dam (Sutlej River)
• Hirakud Dam (Mahanadi River)
• Tehri Dam (Bhagirathi River)

Advantages of Dams

• Provide irrigation water throughout the year.
• Generate hydroelectric power.
• Help in flood control.
• Support drinking water supply.
• Boost agricultural production.

Disadvantages of Dams

• Displacement of people from villages.
• Loss of forests and biodiversity.
• Submergence of fertile land.
• High construction and maintenance cost.
• Can cause environmental imbalance.

Environmental Impacts of Multi-purpose Projects

While dams provide many benefits, they also create serious environmental issues if not managed properly.

• Disruption of natural river flow.
• Loss of aquatic life.
• Soil erosion in surrounding areas.
• Change in local climate patterns.

Narmada Bachao Andolan

Narmada Bachao Andolan is a social movement against large dam projects on the Narmada River, especially the Sardar Sarovar Dam.

Main Concerns

• Displacement of tribal communities.
• Environmental damage due to dam construction.
• Loss of livelihood for affected people.
• Demand for proper rehabilitation and compensation.

NCERT Insight

Rainwater Harvesting

Rainwater harvesting is the process of collecting and storing rainwater for future use. It is one of the oldest and most effective methods of water conservation, especially in areas facing water scarcity.

Importance of Rainwater Harvesting

• Reduces dependence on groundwater.
• Helps recharge aquifers.
• Prevents water shortage in dry regions.
• Reduces urban flooding.

Traditional Water Conservation Methods

India has a long history of traditional water conservation systems developed by local communities according to regional geography and climate.

Examples

• Johads: Small earthen dams in Rajasthan to collect rainwater.
• Khadins: Long earthen embankments used in desert regions.
• Tankas: Underground tanks used for storing rainwater in Rajasthan.
• Baolis: Stepwells used for water storage in North India.

Regional Water Conservation Practices

Rajasthan

• Use of Johads, Khadins, and Tankas.
• Community-managed water systems.

Tamil Nadu

• Rooftop rainwater harvesting is widely practiced.
• Mandatory rainwater harvesting system in urban areas.

Case Study: Alwar Water Conservation (Rajasthan)

Alwar district in Rajasthan is a successful example of community-based water conservation where traditional johads were revived to solve water scarcity.

Impact of Revival

• Groundwater levels increased.
• Dry rivers started flowing again.
• Farming became possible again.
• Migration reduced.

Groundwater Depletion

Groundwater depletion occurs when water is extracted faster than it can be naturally replenished.

Main Causes

• Excessive use in agriculture (tube wells).
• Rapid urbanisation.
• Industrial water consumption.
• Poor recharge systems.

Effects

• Lowering of water table.
• Drying of wells.
• Increased water scarcity.

Role of Community in Water Conservation

Community participation plays a major role in sustainable water management. Local people can manage resources better when they are involved directly.

• Maintenance of traditional systems.
• Collective water usage planning.
• Awareness programs on water saving.
• Local management of water bodies.

NCERT Insight

Revision Flow (Quick Map)

Water Resources
│
├── Importance
│     ├─ Life support
│     ├─ Agriculture
│     ├─ Industry
│     └─ Hydropower
│
├── Distribution
│     ├─ Surface water
│     ├─ Groundwater
│     └─ Rainwater
│
├── Scarcity
│     ├─ Overuse
│     ├─ Pollution
│     └─ Unequal access
│
├── Development Projects
│     ├─ Dams
│     ├─ Multi-purpose projects
│     └─ Environmental impact
│
└── Conservation
      ├─ Rainwater harvesting
      ├─ Traditional systems
      └─ Community participation

Key Terms

One-Line Revision

• Water is essential for all life forms.
• Only a small portion of Earth’s water is usable freshwater.
• Water scarcity is caused by overuse and pollution.
• Dams are used for irrigation and electricity generation.
• Multi-purpose projects have both benefits and drawbacks.
• Rainwater harvesting helps recharge groundwater.
• Traditional methods are still effective in India.
• Community participation is key to water conservation.

Exam Tip Box

Frequently Asked Questions (FAQs)

What is water scarcity?

Water scarcity is the shortage of water when demand is higher than supply.

What is a multi-purpose project?

A dam project used for irrigation, electricity, and water supply.

Why is rainwater harvesting important?

It helps recharge groundwater and reduces water shortage.

What is groundwater depletion?

It is the lowering of water table due to excessive extraction of water.

Related Chapters

• Chapter 1 – Resources and Development
• Chapter 2 – Forest and Wildlife Resources
• Chapter 4 – Agriculture