1. Introduction | Class 10 Water Resources Notes

Hello students! Water is the most essential element for life on Earth. While about three-fourths of our planet is covered with water, only a tiny fraction of it is freshwater that we can actually use. This freshwater is continuously renewed through the hydrological cycle, making it a renewable resource.

However, even though water is renewable, many parts of the world face severe water shortages. We often see devastating floods in places like Assam, yet we worry about absolute water scarcity in the near future. In this chapter, we will explore why we face water scarcity, how we manage our resources through dams, and the traditional ways Indians have harvested rainwater for centuries.

2. Water Scarcity and Conservation

We usually associate water scarcity with dry deserts like Rajasthan, but it can happen anywhere. Scarcity isn’t just about low rainfall; it is often caused by over-exploitation, excessive use, and unequal access to water among different social groups.

Example of Water Scarcity in Arid Regions

As our population grows, the demand for water increases—not just for domestic use, but to produce more food. Farmers often use their own wells and tube-wells to irrigate crops in the dry season, which leads to falling groundwater levels. Additionally, rapid industrialization and urban lifestyles have put immense pressure on our freshwater resources. Sometimes, water is available but polluted by chemicals and industrial waste, making it hazardous for use. To address this, the government has launched initiatives like the Jal Jeevan Mission and Atal Bhujal Yojana to promote smart water management.

3. Multi-Purpose River Projects

India has a long history of building hydraulic structures like dams, canals, and reservoirs. Jawaharlal Nehru famously called these dams the ‘temples of modern India’ because they integrate agricultural development with industrial growth and the village economy.

A dam is essentially a barrier across flowing water that creates a reservoir or lake. Today, these projects serve many purposes: generating hydroelectricity, providing water for domestic and industrial use, controlling floods, and even helping with fish breeding. Examples include the Bhakra-Nangal project on the Sutluj-Beas river and the Hirakud project on the Mahanadi river. However, these large projects have faced criticism because they can disrupt the natural flow of rivers, affect aquatic life, and lead to the displacement of local communities.

4. Rainwater Harvesting

In many parts of India, people have used traditional water-harvesting systems as a sustainable alternative to large dams. These methods are based on deep local knowledge of rainfall and soil types. For instance, in the Western Himalayas, people built diversion channels called ‘guls’ or ‘kuls’ for agriculture.

Traditional Rooftop Rainwater Harvesting Structure

In the arid regions of Rajasthan, ‘rooftop rainwater harvesting’ was the standard way to store drinking water. Houses would have underground tanks called ‘tankas’ to collect rain from the roof via pipes. This water, known as ‘palar pani’, is considered the purest form of natural water. In regions like Meghalaya, a 200-year-old system called Bamboo Drip Irrigation is used to tap stream water using bamboo pipes. Today, states like Tamil Nadu have even made rooftop rainwater harvesting compulsory for all buildings by law.

5. Key Takeaways

• Three-fourths of the Earth’s surface is covered with water, but only a small portion is usable freshwater.
• Water is a renewable resource because it is constantly recharged through the hydrological cycle.
• Water scarcity is caused by a growing population, over-exploitation, and pollution.
• Multi-purpose projects like the Hirakud and Bhakra-Nangal dams provide irrigation, electricity, and flood control.
• Large dams can have ecological impacts, such as fragmenting rivers and causing sedimentation.
• Traditional methods like ‘tankas’ in Rajasthan and ‘kuls’ in the Himalayas are effective for water conservation.
• Tamil Nadu is the first Indian state to make rooftop rainwater harvesting compulsory for all houses.

8. Practice Section: Master the Chapter!

Test your knowledge with these questions based on the notes above.

Part A: True or False (10 Questions)

1. Three-fourths of the earth’s surface is covered with water.
2. Water is considered a non-renewable resource.
3. The Hirakud project is built on the Mahanadi river basin.
4. Irrigated agriculture is the largest consumer of water in India.
5. Jawaharlal Nehru proclaimed dams as the ‘temples of modern India’.
6. ‘Palar pani’ is the term used for rainwater in parts of Rajasthan.
7. Multi-purpose projects never lead to any social or environmental issues.
8. The Bamboo Drip Irrigation system is prevalent in the state of Meghalaya.
9. Tamil Nadu has made rooftop rainwater harvesting compulsory for all houses.
10. The first spell of rain is usually not collected in ‘tankas’ as it cleans the roof.

Part B: Multiple Choice Questions (10 Questions)

1. Which of the following is a cause of water scarcity?
   
   A) Over-exploitation
   
   B) Excessive use
   
   C) Unequal access
   
   D) All of the above
2. What is the purest form of natural water according to Rajasthan traditions?
   
   A) Ground water
   
   B) Palar pani
   
   C) River water
   
   D) Canal water
3. The Bhakra-Nangal project is located in which river basin?
   
   A) Mahanadi
   
   B) Sutluj-Beas
   
   C) Narmada
   
   D) Krishna
4. ‘Guls’ and ‘Kuls’ are diversion channels found in:
   
   A) Rajasthan
   
   B) Bengal
   
   C) Western Himalayas
   
   D) Meghalaya
5. Which river is known as the ‘river of sorrow’ in the Damodar valley?
   
   A) Ganga
   
   B) Damodar
   
   C) Yamuna
   
   D) Kaveri
6. The Sardar Sarovar Dam is built over which river?
   
   A) Ganga
   
   B) Narmada
   
   C) Krishna
   
   D) Godavari
7. The Krishna-Godavari dispute is primarily due to objections from:
   
   A) Punjab and Haryana
   
   B) Karnataka and Andhra Pradesh
   
   C) Rajasthan and Gujarat
   
   D) Kerala and Tamil Nadu
8. What percentage of India’s electricity is generated by hydroelectric power?
   
   A) 10%
   
   B) 22% (approximate historical figure noted in textbooks)
   
   C) 50%
   
   D) 5%
9. Underground tanks for storing rainwater in Rajasthan are called:
   
   A) Kuls
   
   B) Khadins
   
   C) Tankas
   
   D) Johads
10. Which state made rooftop water harvesting compulsory for all houses?
    
    A) Karnataka
    
    B) Tamil Nadu
    
    C) Gujarat
    
    D) Rajasthan

Part C: Short Answer Questions (5 Questions)

1. How does water become a renewable resource?
2. What is the goal of the Jal Jeevan Mission (JJM)?
3. Mention two purposes of multi-purpose projects.
4. What are ‘Khadins’ and ‘Johads’?
5. Why do farmers pump out groundwater in many regions?

Part D: Long Answer Questions (5 Questions)

1. Explain the various causes of water scarcity in cities.
2. Discuss the role and importance of multi-purpose river projects in India.
3. Describe the traditional rooftop rainwater harvesting system in Rajasthan.
4. How do large dams impact aquatic fauna and natural river flow?
5. What is the Bamboo Drip Irrigation system? Describe its efficiency.