Chapter 3: Water Resources

1. Introduction: Water and its Availability

Water is the most essential resource for all life forms on Earth. It covers about 71% of the Earth’s surface, but only a small fraction is available for human use. The global water distribution is highly uneven, with most of it being saline water in oceans.

Global Water Distribution:

- Oceans: 97.5% (Saline)
- Freshwater: 2.5% (Only 0.3% is accessible for human use)
- Freshwater Breakdown:
  - Glaciers and Ice Caps: 68.7%
  - Groundwater: 30.1%
  - Surface Water (Lakes, Rivers, etc.): 1.2%

Water Availability in India:

India receives an annual rainfall of 1,170 mm, but the distribution of water is uneven due to geographical and seasonal variations.
The major river systems in India include the Ganga, Brahmaputra, Indus, Godavari, Krishna, and Narmada.
India has around 4% of the world’s freshwater resources, but over 18% of the world’s population.

2. Water Scarcity and the Need for Water Conservation and Management

Water Scarcity refers to the lack of sufficient available water resources to meet the demands of water usage within a region. It is a growing issue in many parts of India due to:

Increasing Population: More people means more demand for water.
Irrigation in Agriculture: Over-irrigation and inefficient water usage.
Industrialization: Water-intensive industries consume vast amounts of water.
Pollution: Contamination of water resources leads to unusable water.

Need for Water Conservation:

Only 0.3% of the Earth’s water is usable, making it crucial to conserve.
Water conservation ensures the sustainability of water resources for future generations.

Water Management Techniques:

Sustainable Irrigation: Drip irrigation and sprinkler systems.
Rainwater Harvesting: Collecting and storing rainwater for future use.
Watershed Management: Protecting and restoring watershed ecosystems.

3. Multipurpose River Projects and Integrated Water Resource Management (IWRM)

Multipurpose River Projects serve many functions such as irrigation, water supply, hydroelectric power generation, flood control, and recreational uses. These projects provide a holistic approach to water resource management.

Integrated Water Resource Management (IWRM) focuses on managing water resources in a comprehensive manner to balance social, economic, and environmental needs.

4. Hydraulic Structures in Ancient India

India has a rich history of water management. Ancient hydraulic structures reflect the innovative methods used by previous civilizations:

. Dams, Lakes, and Embankments in Ancient India:

In the first century B.C., King Karikala of the Chola Dynasty built the famous Kallanai dam on the Kaveri River in Tamil Nadu. It is one of the oldest water diversion structures in the world.
In ancient India, kings and local rulers built several embankments and dams across rivers to store water for irrigation and other purposes.

. Rainwater Harvesting Systems:

In the dry regions of Rajasthan, the practice of ‘Johads’ (small earthen check dams) and ‘Baoris’ (stepwells) were prevalent. These structures helped store rainwater and recharge groundwater.
In Bhopal, during the 11th century, the largest artificial lake of its time, Bhojsagar, was constructed by Raja Bhoj to supply water to the city and nearby agricultural fields.

. Tanks and Canals:

In the southern part of India, especially in Tamil Nadu, a system of tanks (small reservoirs) was developed for irrigation. These tanks were connected to rivers through canals to ensure that water was available throughout the year.
The Ghadsisar Tank in Jaisalmer, built in 1367 by Maharaja Gadsi Singh, is another example of traditional rainwater harvesting.

. Stepwells:

Stepwells, or ‘Baolis’, were prevalent in western India, especially in Gujarat and Rajasthan. These wells were multi-storied with steps leading down to the water, ensuring access even during dry seasons.
The Rani ki Vav in Patan, Gujarat, built in the 11th century, is a famous example of a stepwell that served as a water reservoir and is a UNESCO World Heritage site today.

. Sophisticated Irrigation Systems:

The Indus Valley Civilization (2500 B.C. – 1800 B.C.) developed sophisticated water management systems. They built well-planned drainage systems and large public baths, and used reservoirs for water conservation.
In ancient Sri Lanka, kings like Parakramabahu I built an extensive irrigation system, which included tanks and canals. Though this system was in Sri Lanka, it influenced Indian practices, especially in southern regions.

5. Rainwater Harvesting: Methods

. Traditional Rainwater Harvesting Methods:

Rooftop Rainwater Harvesting:
- One of the most widely used methods of rainwater harvesting in urban areas.
- Rainwater from rooftops is collected through pipes and directed into storage tanks or underground reservoirs. This stored water can be used for domestic purposes, or it can help recharge groundwater.
‘Khadins’ or ‘Johads’ in Rajasthan:
- In arid regions like Rajasthan, people have developed techniques to capture runoff water during the rainy season.
- Khadins are traditional systems where earthen embankments are built across sloping land to catch and store water. This water slowly percolates into the soil, increasing its moisture content and aiding crop cultivation.
- Johads are small, earthen check dams constructed to store rainwater, recharge groundwater, and support agriculture.
‘Guls’ or ‘Kuls’ in Western Himalayas:
- In the mountainous regions of Jammu and Kashmir, Himachal Pradesh, and Uttarakhand, water channels called guls or kuls are used to divert water from natural streams to fields for irrigation.
- These are small channels dug along mountain slopes, and they help in rainwater management for agriculture.
Bamboo Drip Irrigation in Meghalaya:
- In Meghalaya, an indigenous system of rainwater harvesting uses bamboo pipes to divert water from streams for irrigation, especially in hilly areas.
- This method is very efficient, as it minimizes water wastage and delivers water directly to the root of plants.
‘Tankas’ in Western India:
- In Gujarat and Rajasthan, tankas are underground tanks built to store rainwater, especially in areas with limited rainfall. These tankas collect water from rooftops or courtyards and store it for drinking and other domestic purposes during dry periods.

. Modern Rainwater Harvesting Techniques:

Urban Rainwater Harvesting:
- In modern urban areas, rooftop rainwater harvesting is promoted to recharge groundwater levels. Buildings are required to have systems that direct rooftop runoff into recharge wells, or it can be stored for future use.
- This practice helps reduce dependency on external water sources and also addresses the problem of urban flooding by channeling rainwater away from the streets.
Check Dams and Percolation Pits:
- These are small dams built across streams and rivers to slow down the flow of water. This allows water to seep into the ground, helping recharge groundwater aquifers.
- Percolation pits are dug in urban areas to capture surface runoff and allow it to seep into the ground, enhancing groundwater recharge.
Water Harvesting Pits:
- These are small, shallow pits dug in areas prone to surface runoff. The pits collect rainwater, which then slowly percolates into the ground, improving groundwater levels.

. Importance of Rainwater Harvesting:

Rainwater harvesting is crucial in both rural and urban areas because it helps:
- Reduce water scarcity, particularly in regions with erratic rainfall.
- Recharge groundwater, which is especially important in areas where groundwater levels are depleting.
- Provide a sustainable source of water for agriculture and domestic use.
- Reduce soil erosion and flood risk by controlling runoff.

By following these traditional and modern rainwater harvesting techniques, India has effectively managed its water resources in different geographical regions for centuries

6. Sardar Sarovar Dam: A Brief Insight

The Sardar Sarovar Dam on the Narmada River in Gujarat is one of the largest dams in India. Key facts:

Construction: Initiated in 1987.
Height: 163 meters.
Purpose: Provides irrigation to over 18,000 square kilometers, drinking water to 30 million people, and hydroelectric power.
Controversies: The project faced criticism for displacing large populations and causing environmental damage, but it has been vital for water supply and irrigation in drought-prone regions.

7. Pradhan Mantri Krishi Sinchai Yojana (PMKSY)

PMKSY is a government initiative launched in 2015 to improve the efficiency of water use in agriculture. Its objectives include:

Improving Irrigation Infrastructure: Completing ongoing irrigation projects.
‘Per Drop More Crop’: Promoting efficient water usage through drip and sprinkler systems.
Watershed Development: Aimed at rainfed areas to improve soil moisture and reduce soil erosion.

8. Steps Taken by Local Bodies and the Government to Ensure Water Conservation

The government, along with local bodies, has taken several steps to promote water conservation:

Jal Shakti Abhiyan: A national campaign aimed at rainwater harvesting, renovation of water bodies, and afforestation.
National Water Mission: Focuses on water conservation, recycling, and sustainable management of water resources.
Local Initiatives:
- Panchayats: Encouraging local rainwater harvesting structures.
- Municipal Corporations: Mandating rooftop rainwater harvesting in urban areas.
- Community Participation: Involvement of local communities in watershed development and water management projects.

Conclusion

Water is a finite and critical resource, and its conservation is essential to ensuring sustainable development in India. Through integrated management, conservation efforts, and innovative methods like rainwater harvesting, we can safeguard water resources for future generations.

Here’s a table of some important multipurpose dams in India, along with the rivers they are built on and their primary purposes:

Dam	River	Location	Primary Purpose(s)
Bhakra Dam	Sutlej	Himachal Pradesh	Irrigation, Hydroelectricity, Flood Control
Tehri Dam	Bhagirathi	Uttarakhand	Irrigation, Hydroelectricity, Water Supply
Hirakud Dam	Mahanadi	Odisha	Flood Control, Irrigation, Hydroelectricity
Nagarjuna Sagar Dam	Krishna	Telangana	Irrigation, Hydroelectricity
Sardar Sarovar Dam	Narmada	Gujarat	Irrigation, Water Supply, Hydroelectricity
Rihand Dam	Rihand	Uttar Pradesh	Irrigation, Hydroelectricity
Tungabhadra Dam	Tungabhadra	Karnataka	Irrigation, Hydroelectricity
Mettur Dam	Kaveri	Tamil Nadu	Irrigation, Hydroelectricity, Water Supply
Bhavani Sagar Dam	Bhavani	Tamil Nadu	Irrigation, Water Supply, Hydroelectricity
Indira Sagar Dam	Narmada	Madhya Pradesh	Irrigation, Hydroelectricity, Water Supply
Ukai Dam	Tapti	Gujarat	Irrigation, Hydroelectricity, Flood Control
Koyna Dam	Koyna	Maharashtra	Hydroelectricity, Water Supply
Maithon Dam	Barakar	Jharkhand	Flood Control, Irrigation, Hydroelectricity
Bhima Dam	Bhima	Maharashtra	Irrigation, Hydroelectricity, Flood Control
Krishna Raja Sagar Dam	Kaveri	Karnataka	Irrigation, Water Supply, Hydroelectricity