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Rivers

NCERT Class 5 · EVS Based on NCERT Class 5 EVS textbook · Free CBSE study kit

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Chapter Notes

Overview
This chapter takes students on the journey of a river, from its origin in the mountains to its meeting with the sea, using the Godavari River as a central example. It explains how rivers are formed, how they support life, and the many ways humans depend on them. The chapter also covers the impact of dams, pollution, floods, and droughts, and emphasizes the importance of conserving water. The one big idea a student must walk away with is that rivers are a lifeline for people, animals, and plants, and every small action to save water and keep rivers clean makes a big difference.
Key Concepts (26)
River
A large natural stream of water that flows across the land and empties into a sea or ocean.
e.g. The Godavari River starts at Trimbakeshwar in Maharashtra and flows into the Bay of Bengal.
Tributary
A small stream or river that joins a larger river, making it wider and stronger.
e.g. The Indravati, Sabari, and Manjira are tributaries that join the Godavari River.
Perennial river
A river that flows all year round because it receives water from rain, melting snow, or groundwater throughout the year.
e.g. The Godavari is a perennial river because it flows continuously across all seasons.
Seasonal river
A river that flows only during the rainy season when it receives water from rainfall.
e.g. Many small rivers in dry regions of India are seasonal and dry up in summer.
Delta
A landform created at the mouth of a river where it spreads out into many small streams before entering the sea.
e.g. The Godavari forms a delta when it meets the Bay of Bengal, creating the Coringa Mangrove Forests.
Dam
A giant wall built across a river to block its flow and store water in a large water body called a reservoir.
e.g. The Polavaram Dam and Sriram Sagar Project (SRSP) are dams built on the Godavari River.
Reservoir
A large artificial lake created behind a dam where water is stored for later use.
e.g. The water stored in a reservoir behind a dam is used for drinking, irrigation, and making electricity.
Pollution
The introduction of harmful substances like waste, plastic, and dirty water into a river, making it unsafe for living beings.
e.g. Factories and homes near the Godavari release waste and plastic into the river, polluting its water.
Ecotourism
Visiting natural places like forests, rivers, or mountains to enjoy their beauty, watch animals or birds, and learn about nature without harming the environment.
e.g. People visit the Coringa Wildlife Sanctuary along the Godavari for ecotourism.
Fish migration
The natural movement of fish from the sea into rivers to lay eggs.
e.g. The hilsa (ilish) fish travels from the sea into rivers to lay its eggs.
Water ATM
A special machine that gives clean water when you put in a card or coin, used in places where water is scarce.
e.g. In some parts of India, people use water ATMs to get clean drinking water.
National Water Mission
A government programme that works to manage water properly and help people use water wisely across India.
e.g. The National Water Mission encourages people to save water and use it efficiently.
Namami Gange programme
A government programme to clean the Ganga river so that it stays healthy for people, fish, and birds.
e.g. Under the Namami Gange programme, efforts are made to stop waste from entering the Ganga.
Bhupen Hazarika Setu
The longest river bridge in India, built over the Brahmaputra River, measuring more than 9 kilometres long.
e.g. The Bhupen Hazarika Setu connects parts of Assam across the Brahmaputra.
Chenab rail bridge
The highest railway arch bridge in the world, built over the Chenab River in India.
e.g. The Chenab rail bridge is an engineering marvel in Jammu and Kashmir.
Majuli island
The world's largest river island, formed by the Brahmaputra River in Assam.
e.g. Majuli island is home to many Assamese communities and wildlife.
Hirakud dam
One of the longest earthen dams in the world, stretching over 25 kilometres, built on the Mahanadi River in Odisha.
e.g. The Hirakud dam provides water for irrigation and electricity to many areas.
Ganges river dolphin
India's national aquatic animal, which is blind and uses sound to find its way in the water.
e.g. The Ganges river dolphin is found in the Ganga river and is an endangered species.
Godavari Pushkaram
A religious festival held on the banks of the Godavari River where people take a holy dip in its waters.
e.g. During Godavari Pushkaram, thousands of pilgrims gather at Nashik to bathe in the river.
Dakshina Ganga
A name given to the Godavari River because it flows through southern India and is regarded as sacred like the Ganga.
e.g. The Godavari is called Dakshina Ganga because it is the holiest river in South India.
Coringa Mangrove Forests
A mangrove forest at the delta of the Godavari River where freshwater meets the salty sea.
e.g. The Coringa Mangrove Forests are home to many plants and animals, including the Indian golden gecko.
Kawal Tiger Reserve
A wildlife reserve located along the Godavari River in Telangana, home to tigers and other animals.
e.g. The Kawal Tiger Reserve is one of the protected areas through which the Godavari flows.
Pench National Park
A national park located along the Godavari River, known for its tiger population.
e.g. Pench National Park is a popular destination for wildlife safaris.
Sriram Sagar Project (SRSP)
A dam and irrigation project built on the Godavari River in Telangana.
e.g. The Sriram Sagar Project provides water for farming and drinking in the region.
Polavaram Dam
A major dam built on the Godavari River in Andhra Pradesh for irrigation and electricity generation.
e.g. The Polavaram Dam is one of the largest irrigation projects in India.
Coringa Wildlife Sanctuary
A wildlife sanctuary located at the delta of the Godavari River, protecting mangrove forests and wildlife.
e.g. The Coringa Wildlife Sanctuary is home to the Indian golden gecko and barking deer.
How It Works
Journey of a River from Source to Sea
  1. Step 1 — A river begins high up in the mountains or hills, often as a small stream from melting snow or a spring.
  2. Step 2 — As the stream flows downhill, rainwater and other small streams (tributaries) join it, making it wider and stronger.
  3. Step 3 — The river flows across the land, passing through forests, fields, and towns, providing water to people, animals, and plants.
  4. Step 4 — When the river reaches the sea, it spreads out into many small streams, forming a delta where freshwater meets salty seawater.
  5. Step 5 — The river ends at the sea, often creating mangrove forests or wetlands at its mouth.
💡 Students often forget that a river starts as a small stream and grows by collecting water from tributaries. They also confuse 'delta' with 'estuary' — in this chapter, the Godavari forms a delta, not an estuary.
How Dams Affect a River and Its Surroundings
  1. Step 1 — A dam is built as a giant wall across the river to block its natural flow.
  2. Step 2 — Water accumulates behind the dam, forming a large reservoir.
  3. Step 3 — The stored water is used for drinking, irrigation (growing crops), and generating electricity.
  4. Step 4 — The reservoir floods the land upstream, forcing animals and people to leave their homes and relocate.
  5. Step 5 — The dam changes the river's flow downstream, affecting the natural habitat of plants and animals.
💡 Students often think dams are only beneficial. The chapter clearly states that dams also cause displacement of people and animals and flood forests. Both positive and negative effects must be mentioned in answers.
How Rivers Get Polluted
  1. Step 1 — Waste, plastic, and dirty water from homes, factories, and farms are dumped into rivers.
  2. Step 2 — Harmful chemicals and soapy water dissolve or mix with the river water, making it unsafe.
  3. Step 3 — Fertilizers from fields wash into the river, causing plants and algae to grow very fast, forming a 'green blanket' on the surface.
  4. Step 4 — This green blanket chokes the river, making it hard for fish to breathe and the water unsafe for drinking.
  5. Step 5 — Animals, birds, and people who depend on the river get sick or disappear.
💡 Students often think pollution is only visible dirt. The chapter emphasizes that even clean-looking water can carry harmful chemicals that dissolve in it, like soap or fertilizers.
How Flooding Happens and Its Effects
  1. Step 1 — When there is too much rain, all the water rushes into the river.
  2. Step 2 — The river becomes faster, deeper, and bigger, overflowing its banks.
  3. Step 3 — The floodwater spreads over land, flooding houses, fields, and roads.
  4. Step 4 — Flooding causes damage: dirty water, broken roads, lost crops, no electricity, spread of diseases, damaged homes, and schools shutting down.
  5. Step 5 — Trees help slow down rainwater and allow soil to soak it up, reducing flooding. Without trees, water runs off faster and causes more flooding.
💡 Students often forget the role of trees in preventing floods. The chapter shows that trees help the soil absorb water, so deforestation worsens flooding.
What Happens When a River Runs Dry
  1. Step 1 — When there is no rain for a long time, rivers and reservoirs dry up.
  2. Step 2 — People have no water for drinking, cooking, bathing, or cleaning.
  3. Step 3 — Crops cannot grow, and animals suffer.
  4. Step 4 — Families may have to leave their homes and move to places where water is available.
  5. Step 5 — Perennial rivers like the Godavari flow all year, so they can support people even in dry seasons, but seasonal rivers dry up completely.
💡 Students often confuse 'perennial' with 'always flooded'. A perennial river flows all year but can still have low water levels. A seasonal river only flows in the rainy season.
Exam Traps — Don't Make These Mistakes
⚠ Confusing Tributary with Distributary
✗ A tributary is a small river that flows away from the main river.
→ A tributary joins the main river and adds water to it, not flows away. A distributary is a branch that flows away from the main river, especially in a delta.
✓ A tributary is a small stream or river that joins a larger river, making it wider and stronger.
⚠ Thinking All Rivers Are Perennial
✗ All rivers flow throughout the year.
→ Only perennial rivers like the Godavari flow all year. Seasonal rivers flow only during the rainy season.
✓ Perennial rivers flow all year round, while seasonal rivers flow only when they receive water in the rainy season.
⚠ Believing Dams Have Only Benefits
✗ Dams are good because they store water for drinking and farming.
→ The chapter clearly states that dams also flood land, forcing people and animals to leave their homes. Both positive and negative effects must be mentioned.
✓ Dams store water for drinking, irrigation, and electricity, but they also flood forests and homes, displacing people and animals.
⚠ Mistaking Delta for Estuary
✗ A delta is where a river meets the sea in a single channel.
→ A delta is formed when a river spreads out into many small streams before entering the sea. An estuary is a single, funnel-shaped mouth.
✓ A delta is a landform created at the mouth of a river where it spreads out into many small streams before entering the sea.
⚠ Thinking Pollution Is Only Visible Dirt
✗ River water is clean if it looks clear.
→ The chapter explains that harmful chemicals like soap, fertilizers, and pesticides can dissolve in water and make it unsafe even if it looks clean.
✓ River water can look clean but still carry dissolved harmful chemicals that hurt living beings.
⚠ Confusing the Cause of the 'Green Blanket'
✗ The green blanket on a river is caused by plastic waste.
→ The green blanket is caused by fertilizers washing into the river, making plants and algae grow very fast and cover the surface.
✓ Fertilisers from fields wash into rivers and cause plants and algae to grow very fast, forming a 'green blanket' that chokes the river.
Compare & Contrast
Flow of water throughout the year
Perennial river
Seasonal river
A perennial river flows all year round (e.g., Godavari), while a seasonal river flows only during the rainy season.
Direction of flow relative to the main river
Tributary
Distributary
A tributary joins the main river and adds water to it, while a distributary branches away from the main river, especially in a delta.
Structure vs. water body
Dam
Reservoir
A dam is the giant wall built across a river to block its flow, while a reservoir is the large water body that forms behind the dam.
Exam Focus
Marks pattern: This chapter typically appears with 2-3 MCQs (1 mark each), 1-2 Short Answer questions (2-3 marks each), and 1 Long Answer question (5 marks) focusing on the journey of a river, dams, pollution, or floods.
Most asked: Definition and examples of tributaries · Difference between perennial and seasonal rivers · Formation of a delta · Positive and negative effects of dams · Causes and effects of river pollution · Causes and effects of floods · Ways to save water and keep rivers clean
Don't skip: Explain the journey of a river from its source to the sea with the example of the Godavari.; What are the advantages and disadvantages of building dams on rivers?; How does pollution affect rivers and the living beings that depend on them?; What causes floods and what safety measures should be taken during a flood?
One-Line Revision (read aloud before the exam)
  1. A river begins as a small stream in the mountains and grows by collecting water from tributaries.
  2. The Godavari is the second longest river in India and is called Dakshina Ganga.
  3. A tributary is a small stream that joins a larger river.
  4. Perennial rivers flow all year round; seasonal rivers flow only in the rainy season.
  5. A delta is formed when a river spreads into many streams before meeting the sea.
  6. A dam is a wall that blocks a river and creates a reservoir for storing water.
  7. Dams provide water for drinking, farming, and electricity but flood homes and forests.
  8. River pollution is caused by waste, plastic, chemicals, and fertilizers.
  9. Fertilisers in rivers cause a 'green blanket' of algae that chokes the water.
  10. Floods happen when too much rain makes a river overflow its banks.
  11. Trees help prevent floods by slowing down rainwater and helping the soil soak it up.
  12. During a flood, move to higher ground, avoid flood water, and disconnect electricity.
  13. When a river runs dry, people and animals suffer and may have to move away.
  14. Save water by turning off taps while brushing, fixing leaks, and reusing water.
  15. The Namami Gange programme works to clean the Ganga river.
  16. The Ganges river dolphin is India's national aquatic animal and uses sound to navigate.
  17. Every small action to save water and keep rivers clean makes a big difference.

MCQs — 10 Questions with Answers

Q1. Where does the Godavari river begin its journey?

  • A. In the Brahmagiri Hills of the Western Ghats at Trimbakeshwar, Maharashtra ✓
  • B. In the Eastern Ghats of Odisha
  • C. In the Himalayas of Himachal Pradesh
  • D. In the Deccan Plateau of Karnataka

Answer: A — The chapter clearly states that Godavari's journey begins high up in the Western Ghats at Trimbakeshwar in Maharashtra.

Q2. What is a tributary?

  • A. A large lake that stores water
  • B. A small stream that joins a main river and makes it wider and stronger ✓
  • C. A wall built across a river
  • D. A type of fish found in rivers

Answer: B — The chapter defines tributaries as small streams joining the main river that make it wider and stronger as the journey continues.

Q3. How long is the Godavari river?

  • A. 865 kilometres
  • B. 1,200 kilometres
  • C. 1,465 kilometres ✓
  • D. 2,000 kilometres

Answer: C — The chapter states that Godavari travels 1,465 kilometres before joining the Bay of Bengal.

Q4. Which of the following is a perennial river?

  • A. A river that flows only during the rainy season
  • B. A river that flows all year round and never dries up completely ✓
  • C. A river that stops flowing when there are no rains
  • D. A river that changes its path every year

Answer: B — The chapter explains that a perennial river flows all year round, while seasonal rivers flow only when receiving water in the rainy season.

Q5. What is a delta?

  • A. A tall mountain where a river starts
  • B. A wall built to stop a river
  • C. The place where a river spreads out into many small streams when it reaches the sea ✓
  • D. A type of water storage in the ground

Answer: C — The chapter states that when Godavari reaches the sea, it spreads out into many small streams that form a delta, like the Coringa Mangrove Forests.

Q6. What is a dam and why do people build it?

  • A. A dam is a small bridge across a river to help people cross
  • B. A dam is a giant wall that blocks a river's flow and stores water so people can use it during dry seasons for drinking, growing crops, and making electricity ✓
  • C. A dam is a type of fish found in rivers
  • D. A dam is a forest that grows near rivers

Answer: B — The chapter explains that a dam is like a giant wall that blocks a river's flow and stores water in a reservoir for many uses including drinking, farming, and electricity.

Q7. When you open a tap at home and water comes out, where does that water likely come from?

  • A. From rain falling directly into pipes
  • B. From a river through pipes and canals carried from dams and water bodies ✓
  • C. From under the ground only, never from rivers
  • D. From the sea mixed with fresh water

Answer: B — The chapter states that water for all houses comes from rivers; it is carried in pipes and canals and shared by many through dams and water storage.

Q8. What problem occurs when too much fertiliser from farms washes into a river?

  • A. The river becomes too warm
  • B. Plants and organisms grow so fast that they cover the river surface like a 'green blanket', making it hard for fish to breathe and water unsafe to drink ✓
  • C. The river becomes too salty
  • D. The river dries up completely

Answer: B — The chapter explains that fertilisers make plants grow very fast until they cover the surface like a 'green blanket', choking life inside and making water unsafe.

Q9. In the experiment with two glasses of water, sugar and oil were added. Which substance dissolved in water?

  • A. Oil dissolved in water and became invisible
  • B. Sugar dissolved in water and the glass became clear, while oil did not dissolve and the glass remained cloudy ✓
  • C. Neither sugar nor oil dissolved in water
  • D. Both sugar and oil dissolved equally well

Answer: B — The chapter's Activity 3 shows that sugar dissolves in water (like salt and some chemicals), while oil does not dissolve; this shows why some pollutants hide in water.

Q10. What is the greatest problem that occurs after a dam is built on a river?

  • A. The river becomes too clean
  • B. Fish population increases greatly
  • C. Land gets flooded, forests are destroyed, and many people and animals lose their homes and have to move away ✓
  • D. The river stops flowing completely forever

Answer: C — The chapter clearly states that while dams help store water for use, they also flood land that was once home to animals and people, forcing many to leave their homes.

Flashcards

What is a river?

A river is a large flowing body of water that travels from mountains or highlands to the sea.

What are tributaries?

Tributaries are small streams that join a main river and make it wider and stronger.

What is a perennial river?

A perennial river is one that flows all year round, never drying up completely.

Name the river mentioned in this chapter.

The river is Godavari, which is the second longest river in India.

What is a delta?

A delta is where a river spreads out into many small streams as it reaches and meets the sea.

What is a dam?

A dam is a giant wall built across a river to block its flow and store water in a large body called a reservoir.

How does a river help people?

Rivers provide water for drinking, cooking, washing, growing crops, making electricity, and supporting jobs like fishing.

What is the green blanket problem in rivers?

When too much fertiliser washes into a river, plants grow so fast they cover the water surface, making it hard for fish to breathe.

Why is river pollution dangerous even when water looks clean?

Harmful chemicals and dirty soapy water can hide in rivers; some things that pollute do not dissolve, so the river looks clean but is actually unsafe.

What happens to people when a dam is built across a river?

Lands get flooded, forests are destroyed, and many people and animals have to leave their homes and move elsewhere.

Important Board Questions

What is the Godavari river also called and why? [1 mark]

Look for the name given to Godavari in the beginning section. The reason is related to where it flows and why people consider it sacred.

Name two ways in which rivers help people in their daily life. [2 marks]

Think about what you use water for at home and in farms. The chapter lists drinking, cooking, washing, farming, and electricity generation.

Explain what happens to the river and the people living near it when a dam is built. Give one example. [3 marks]

A dam blocks a river and stores water in a reservoir. This helps many people but also floods land and forces people to move. Think about what animals and forests face.

Describe three problems that river pollution causes and explain how people can help reduce river pollution. Draw and label a simple diagram showing a clean river with its wildlife. [5 marks]

Pollution problems include: plastic and waste harm animals; chemicals hide in water making it unsafe; fertilisers create a green blanket that stops fish breathing. Solutions: use eco-friendly products, reduce waste, keep rivers clean. Draw a river with fish, birds, trees, and clean water.

True or False: A seasonal river flows all year round like Godavari. Give a reason for your answer. [2 marks]

Read the section about perennial and seasonal rivers. A seasonal river only flows when it receives water in the rainy season; a perennial river flows all year.

Assertion-Reason Questions for Rivers

Q1. Assertion (A):

River Godavari is called 'Dakshina Ganga' because it is the second longest river in India.

Reason (R):

Godavari flows through southern India and is regarded as sacred, similar to river Ganga in the north.

Answer: C — A is true but R is false — The assertion is true that Godavari is the second longest river, but the reason given is not the correct explanation. The actual reason for the name 'Dakshina Ganga' is that it flows through southern India and is sacred, not because it is the second longest.

Q2. Assertion (A):

Dams help people get water during dry seasons and to make electricity.

Reason (R):

Dams block the river's flow and store water in large water bodies called reservoirs.

Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are true. The reason correctly explains how dams work (by blocking flow and storing water in reservoirs), which is how they help people get water during dry seasons and generate electricity.

Q3. Assertion (A):

Fish and turtles are disappearing from polluted rivers.

Reason (R):

Pollution in rivers causes bad smell and makes the water look dirty.

Answer: B — Both A and R are true, but R is NOT the correct explanation of A — The assertion is true—the chapter states that fish and turtles are disappearing from polluted rivers. However, the reason is not the complete explanation. Fish disappear because pollution harms them and makes water unsafe, not just because of smell and appearance.

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Case-Based Questions (CBQ) for Rivers

Case Study:

Rahul's grandmother told him that when she was young, the river near their village was very clean and clear. Fish and birds were plenty. Now, after factories were built nearby and people throw plastic waste into it, the river looks dirty and smells bad. Rahul wants to help keep the river clean like his grandmother remembers.

Q1. What has caused the river near Rahul's village to become dirty?

  • A. Factories dumping waste and people throwing plastic into it ✓
  • B. Too many fish living in it
  • C. The river flowing too fast
  • D. Heavy rainfall in recent years

Answer: A

Q2. Why were there more fish and birds in the river when Rahul's grandmother was young?

  • A. Because there was less pollution and the water was clean and clear ✓
  • B. Because there were more dams built then
  • C. Because people did not live near the river
  • D. Because the river was frozen

Answer: A

Q3. What can Rahul do to help protect the river like his grandmother wants?

  • A. Throw more plastic into the river
  • B. Not litter waste, use eco-friendly products, and encourage others not to pollute the river ✓
  • C. Build a dam to store the dirty water
  • D. Move away from the village

Answer: B

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