Water Resources Class 10: Notes, Concepts and Board Answers

What Water Resources is about

Weightage: Geography carries 20 of the 80 theory marks; this chapter shares them with Resources and Development, Forest and Wildlife Resources, Agriculture, Minerals and Energy Resources, Manufacturing Industries and Lifelines of National Economy.Source: CBSE Social Science syllabus 2026-27, Geography

In real board papers: asked in 19 of the 21 board papers we hold (2023 to 2026), on average 3.5 marks per paper. See the questions

Key concepts

Water: renewable but limited

NCERT section Water Scarcity and the Need for Water Conservation and Management

About three-fourth of the earth's surface is water, but only a small share of it is freshwater that people can use. This freshwater comes from three sources:

• rain and snow (precipitation)
• water flowing over land (surface run off)
• water stored under the ground (groundwater)

Why is water called renewable? All water keeps moving through the hydrological cycle. It evaporates, falls again as precipitation and refills rivers and underground stores. So the supply is continually renewed and recharged.

Renewable does not mean unlimited. The amount of water available changes from place to place and from season to season, because seasonal and annual precipitation varies. If people take water out faster than the cycle refills it, the stores run down.

This is the puzzle the whole chapter answers: a renewable resource can still become scarce. Keep the idea in mind. The next two concepts explain the human reasons behind scarcity: how much water is used, and how clean it is.

Worked example

[Advanced] Three-fourth of the earth is covered with water, and water is a renewable resource. Yet many regions of India suffer from water shortage. Explain this contradiction.

Try it first, then show the solutionSolution

1. Only a small proportion of the earth's water is freshwater that can be put to use (1)
2. Availability varies over space and time because seasonal and annual precipitation varies (1)
3. In most cases scarcity comes from over-exploitation, excessive use and unequal access among social groups, so water is used faster than the hydrological cycle renews it (1)

Answer: Only a small share of the earth's water is usable freshwater. Its availability varies over space and time because seasonal and annual precipitation varies. In most cases scarcity is caused by over-exploitation, excessive use and unequal access among social groups. As a result, water is used faster than the hydrological cycle can renew it.

Water scarcity caused by quantity: over-use and unequal access

NCERT section Water Scarcity and the Need for Water Conservation and Management

When you hear 'water shortage', you may picture the deserts of Rajasthan and women carrying many matkas over long distances. Low rainfall does matter. But NCERT stresses that in most cases scarcity is caused by people: over-exploitation, excessive use and unequal access among social groups. That is why areas with ample water, including many cities, still face scarcity.

Follow the chain of causes:

• Population: more people need more water for homes and for growing more food.
• Irrigation: to raise food-grain output, water is over-used to expand irrigated land for dry-season farming. Irrigated agriculture is the largest consumer of water. Private wells and tube-wells lower groundwater levels, which hurts water availability and food security.
• Industrialisation: industries are heavy users of water and also need power, much of it hydroelectric.
• Urbanisation: dense cities and urban lifestyles raise both water and energy demand. Housing societies pump their own groundwater, which depletes fragile resources.

For farming, NCERT's remedy is drought resistant crops and dry farming techniques.

Worked example

[Advanced, 5 marks] 'Many Indian cities have ample water resources and still suffer from water scarcity.' Explain five human factors responsible for this.

Try it first, then show the solutionSolution

1. Large and growing population needs more water for domestic use and for producing more food (1)
2. Water is over-exploited to expand irrigated area for dry-season farming; irrigated agriculture is the largest consumer (1)
3. Wells and tube-wells lower groundwater levels, affecting water availability and food security (1)
4. Growing industries are heavy water users and also need hydroelectric power (1)
5. Dense urban centres, urban lifestyles and housing societies pumping their own groundwater deplete resources; access to water is unequal among social groups (1)

Answer: - A large, growing population needs more water for homes and for growing more food.
- Water is over-exploited to expand irrigated land for dry-season farming. Irrigated agriculture is the largest consumer of water.
- Farmers' own wells and tube-wells lower groundwater levels, which threatens water availability and food security.
- Industries use a lot of water and also need power, much of it hydroelectric.
- Dense cities with urban lifestyles raise demand. Housing societies pump their own groundwater, depleting fragile resources. Unequal access among social groups leaves some people short even where water exists.

Scarcity caused by quality and the need for conservation

NCERT section Water Scarcity and the Need for Water Conservation and Management

Scarcity is not only about how much water there is. An area may have enough water and still suffer because the water is of bad quality. Domestic and industrial wastes, chemicals, and the pesticides and fertilisers used in farming can pollute water and make it hazardous for people.

Why must we conserve and manage water? NCERT gives four reasons:

• to protect ourselves from health hazards
• to ensure food security
• to keep our livelihoods and productive activities going
• to prevent damage to natural ecosystems

If water is over-exploited and mismanaged, the resource becomes poorer and an ecological crisis can follow, with deep effects on our lives.

The government has also acted:

• Jal Jeevan Mission: aims to give every rural household an assured supply of safe piped drinking water at 55 litres per person per day.
• Atal Bhujal Yojana: works in water-stressed gram panchayats of seven states and tries to change people's attitude from consumption to conservation.

Worked example

[HOTS] Suppose a village has a river flowing beside it all year. A health worker warns families not to drink its water. Drains from homes empty into the river, a factory upstream releases waste into it, and rain washes pesticides and fertilisers from nearby fields into it.
(a) What kind of water scarcity does this village face? (1)
(b) Explain why the village faces scarcity despite the river, and why conserving and managing water matters here. (2)

Try it first, then show the solutionSolution

1. (a) Qualitative scarcity: water is available in quantity but its quality is bad (1)
2. (b) Domestic and industrial wastes, chemicals, pesticides and fertilisers make the water hazardous for human use (1)
3. (b) Conservation and management are needed to safeguard health, protect food security and livelihoods, and prevent degradation of the river ecosystem (1)

Answer: (a) The village faces scarcity due to poor quality of water, not a lack of quantity.

(b) Domestic sewage, factory waste, pesticides and fertilisers pollute the river and make it hazardous to use. Managing and conserving this water is needed to protect people's health, food security and livelihoods, and to stop the degradation of the river's ecosystem.

Hydraulic structures in ancient India

NCERT section Multi-Purpose River Projects and Integrated Water Resources Management

Building structures to conserve water is not new in India. Archaeological and historical records show that from ancient times people built dams of stone rubble, reservoirs or lakes, embankments and canals for irrigation. Modern India continued this tradition by building dams in most river basins.

NCERT gives a timeline worth knowing:

• First century B.C.: Sringaverapura near Allahabad had an advanced water harvesting system that channelled the flood water of the Ganga.
• Time of Chandragupta Maurya: dams, lakes and irrigation systems were built extensively.
• Other sites: advanced irrigation works have been found in Kalinga (Odisha), Nagarjunakonda (Andhra Pradesh), Bennur (Karnataka) and Kolhapur (Maharashtra).
• 11th century: Bhopal Lake, one of the largest artificial lakes of its time.
• 13th-14th century: the tank at Hauz Khas, Delhi, built by Allauddin Khilji to supply water to the Siri Fort area.

What these examples prove in an answer: India had advanced water engineering long ago. This tradition links both to modern dams and to traditional rainwater harvesting.

Worked example

[Board] Give three examples to show that India had a tradition of building hydraulic structures in ancient and medieval times.

Try it first, then show the solutionSolution

1. Sringaverapura near Allahabad, first century B.C., had a system channelling the flood water of the Ganga (1)
2. In Chandragupta Maurya's time, dams, lakes and irrigation systems were extensively built (1)
3. Bhopal Lake was built in the 11th century, or the Hauz Khas tank in Delhi was built by Allauddin Khilji in the 13th-14th century for the Siri Fort area (1)

Answer: - In the first century B.C., Sringaverapura near Allahabad had a water harvesting system that channelled the Ganga's flood water.
- During Chandragupta Maurya's time, dams, lakes and irrigation systems were built on a large scale.
- In the 11th century, Bhopal Lake was built, one of the largest artificial lakes of its time.

Dams and multi-purpose river projects

NCERT section Multi-Purpose River Projects and Integrated Water Resources Management

A dam is a barrier across flowing water that blocks, directs or slows its flow, usually creating a reservoir or lake. Most dams have a spillway or weir, over which water flows at times or all the time. Dams are classified by structure and material (timber, embankment, masonry) or by height (large and major, or low, medium and high).

Earlier, dams stored river and rainwater mainly for irrigation. Today one dam serves many uses together: irrigation, electricity, water for homes and industries, flood control, recreation, inland navigation and fish breeding. Because these uses are integrated, such dams are called multi-purpose projects. Three examples:

• Bhakra-Nangal (Sutluj-Beas basin): hydel power and irrigation.
• Hirakud (Mahanadi basin): water conservation with flood control.
• Sardar Sarovar (Narmada, Gujarat): covers four states and serves drought-prone and desert areas.

After Independence, Jawaharlal Nehru called dams the 'temples of modern India'. He believed they would join farming and the village economy with rapid industrialisation and urban growth.

Worked example

[Board] Why are dams today called multi-purpose projects? Explain with two examples from Indian river basins.

Try it first, then show the solutionSolution

1. Dams were earlier built mainly for irrigation; now the impounded water serves many uses such as power, domestic and industrial supply, flood control, recreation, navigation and fish breeding, integrated with one another (1)
2. Bhakra-Nangal in the Sutluj-Beas basin is used for both hydel power and irrigation (1)
3. Hirakud in the Mahanadi basin integrates conservation of water with flood control (1)

Answer: Dams were once built mainly to store water for irrigation. Today their water also generates electricity and supplies homes and industries. It is used for flood control, recreation, inland navigation and fish breeding, all integrated together. For example, Bhakra-Nangal (Sutluj-Beas basin) serves both hydel power and irrigation, and Hirakud (Mahanadi basin) combines water conservation with flood control.

Problems of multi-purpose projects and inter-state disputes

NCERT section Multi-Purpose River Projects and Integrated Water Resources Management

In recent years, large dams have faced scrutiny and opposition. To evaluate them fairly, sort the problems into groups:

• River ecology: damming changes a river's natural flow. Too little sediment moves downstream and too much settles at the reservoir bottom. Stream beds become rockier and habitats for aquatic life get poorer. Dams also break rivers into parts, so aquatic fauna find it hard to migrate, especially for spawning.
• Submergence: reservoirs on floodplains drown vegetation and soil, which decompose over time.
• Floods: ironically, sedimentation in reservoirs has triggered floods, and big dams have mostly failed to control floods during excessive rain. Floods cause soil erosion, and floodplains lose silt, a natural fertiliser, which adds to land degradation.
• Other effects: induced earthquakes, water-borne diseases, pests and pollution from excessive water use.
• Cropping pattern: irrigation has pushed farmers towards water-intensive commercial crops, causing salinisation of soil.

Sharing water also causes conflict. In the Krishna-Godavari dispute, Karnataka and Andhra Pradesh objected to Maharashtra diverting more water at Koyna, because it would cut downstream flow.

Worked example

[Advanced, 5 marks] 'Dams built to control floods have sometimes caused floods.' Examine this statement and explain three other harmful effects of multi-purpose projects.

Try it first, then show the solutionSolution

1. Sedimentation at the reservoir bottom has triggered floods, and big dams have mostly failed to control floods during excessive rainfall (1)
2. These floods caused loss of life and property and extensive soil erosion; floodplains were deprived of silt, adding to land degradation (1)
3. Damming fragments rivers and disturbs natural and sediment flow, harming aquatic life and fish migration for spawning (1)
4. Reservoirs submerge vegetation and soil on floodplains, which decompose over time (1)
5. Projects have induced earthquakes, water-borne diseases and pests, and irrigation-led water-intensive cropping has caused salinisation of soil (1)

Answer: The statement is valid. Sediment collects at the reservoir bottom, and this has triggered floods. Big dams have mostly failed to control floods during excessive rain. Such floods destroy life and property, erode soil and deprive floodplains of fertile silt, worsening land degradation.

Other harmful effects:
- Dams fragment rivers and disturb sediment flow, harming aquatic habitats and blocking fish migration for spawning.
- Reservoirs submerge vegetation and soil, which decompose.
- Projects have induced earthquakes, spread water-borne diseases and pests, and encouraged water-intensive crops that salinise the soil.

Traditional rainwater harvesting systems

NCERT section Rainwater Harvesting

Big dams brought problems and growing resistance, so many people saw water harvesting as a workable alternative, both socio-economically and environmentally. People in ancient India knew their rainfall and soils well, and they designed methods to suit local conditions and needs:

• Hills and mountains: diversion channels called guls or kuls in the Western Himalayas, used for farming.
• Rajasthan: rooftop rainwater harvesting to store drinking water.
• Flood plains of Bengal: inundation channels to irrigate fields.
• Arid and semi-arid areas: fields turned into rain-fed storage where water stands and moistens the soil, like khadins in Jaisalmer and johads elsewhere in Rajasthan.

The tankas of Bikaner, Phalodi and Barmer show this thinking clearly. Underground tanks, some as big as a room, were built inside the house or courtyard and joined to the sloping roof by a pipe. The first spell of rain was not collected, because it cleaned the roof and pipes. The stored water, called palar pani, lasted till the next rain.

Worked example

[Advanced, 5 marks] 'Traditional water harvesting in India was designed to suit local ecological conditions.' Justify the statement by matching five methods with the regions and conditions they suited.

Try it first, then show the solutionSolution

1. Hill and mountain regions: guls or kuls of the Western Himalayas diverted water for agriculture (1)
2. Rajasthan: rooftop rainwater harvesting stored drinking water (1)
3. Flood plains of Bengal: inundation channels irrigated fields (1)
4. Arid and semi-arid regions: khadins in Jaisalmer and johads in other parts of Rajasthan held rainwater in fields to moisten the soil (1)
5. Bikaner, Phalodi and Barmer: underground tankas linked to sloping roofs stored drinking water till the next rain (1)

Answer: People knew local rainfall and soils, so each method fitted its region:
- In the Western Himalayas, guls or kuls diverted mountain water to fields.
- In Rajasthan, rooftop harvesting stored drinking water.
- In Bengal's flood plains, inundation channels used flood water to irrigate fields.
- In arid and semi-arid areas, khadins (Jaisalmer) and johads (other parts of Rajasthan) let rainwater stand in fields and moisten the soil.
- In Bikaner, Phalodi and Barmer, underground tankas joined to sloping roofs stored rainwater, a reliable drinking source in summer.

Modern adaptations of rooftop rainwater harvesting

NCERT section Rainwater Harvesting

Old ideas are being adapted today in rural and urban India. In a modern rooftop system:

• Rainwater is collected through a PVC pipe.
• It is filtered through sand and bricks.
• An underground pipe takes it to a sump for immediate use.
• Extra water goes to a well and recharges the groundwater, through a hand pump or an abandoned dugwell.

Know these examples:

• Gendathur (Mysuru, Karnataka): about 200 households in this remote village harvest rooftop water. With about 1,000 mm of rain a year, each house can collect and use about 50,000 litres annually.
• Shillong (Meghalaya): Cherapunjee and Mawsynram, 55 km away, get the world's highest rainfall, yet Shillong faces acute shortage. Nearly every house harvests rooftop water, which meets about 15-25 per cent of its needs.
• Tamil Nadu: the first state to make rooftop harvesting compulsory for all houses, with legal provisions to punish defaulters.

The opposite trend is seen in western Rajasthan. There the perennial Indira Gandhi Canal has reduced the use of tankas, though some families keep them because they dislike the taste of tap water.

Worked example

[HOTS, 4 marks] Read the passage and answer the questions.

Rooftop rainwater harvesting is spreading in very different parts of India. In Shillong, the capital of Meghalaya, almost every household has a rooftop structure. This is so even though Cherapunjee and Mawsynram, only 55 km away, receive the highest rainfall in the world. These structures meet about 15 to 25 per cent of a household's water needs. Far to the south, in Gendathur, a remote village in Mysuru, Karnataka, nearly 200 households have fitted rooftop systems. The village has become known as rich in rainwater. With about 1,000 mm of rain a year, each house can collect and use about 50,000 litres annually. Tamil Nadu has gone a step further by making rooftop harvesting compulsory for every house, with legal action against those who do not follow the rule.

(i) What does the example of Shillong show about heavy rainfall nearby and water supply in a city? (1)
(ii) Which state has made rooftop harvesting compulsory, and how does it make sure people follow the rule? (1)
(iii) Explain two reasons why rooftop harvesting suits both a city like Shillong and a village like Gendathur. (2)

Try it first, then show the solutionSolution

1. (i) Heavy rainfall nearby does not guarantee enough water; Shillong still faces acute shortage and households must harvest rooftop water (1)
2. (ii) Tamil Nadu; it has legal provisions to punish defaulters (1)
3. (iii) Rain is caught where it falls, on each house's own roof, so each household gets its own store and depends less on other sources (1)
4. (iii) Extra water can be sent to a well to recharge groundwater, and the method works in any place that gets rain, urban or rural (1)

Answer: (i) Being close to places with the world's highest rainfall does not guarantee water. Shillong still faces acute shortage, so households harvest rooftop water to meet part of their needs.

(ii) Tamil Nadu. It has legal provisions to punish those who do not install the structure.

(iii) Each house catches the rain falling on its own roof, giving it a local store and reducing dependence on other supplies. Extra water can also recharge groundwater through wells, so the method works in both towns and villages.

Bamboo drip irrigation system of Meghalaya

NCERT section Bamboo Drip Irrigation System

In Meghalaya, a 200-year-old method taps stream and spring water through bamboo pipes. It shows how a local material and gravity can do the work of modern drip irrigation.

How it works, step by step:

• Bamboo pipes carry water from perennial springs on the hilltops down to the lower reaches by gravity, so no pump is needed.
• Bamboo channel sections divert the water to the plant site. There it is split into branches made of different bamboo pipes. Farmers control the flow by changing the position of the pipes.
• Where the pipes cross a road, they are taken high above the land.
• At the last stage, smaller channel sections and diversion units drop the water near the roots of the plant.

Why it saves water: about 18-20 litres of water enters the system and is carried over hundreds of metres. At the plant, this is reduced to only 20-80 drops per minute. Water reaches exactly where roots need it, with little waste. This is the same idea as 'per drop more crop', an aim of the Pradhan Mantri Krishi Sinchayee Yojana.

Worked example

[Board] Explain how the bamboo drip irrigation system of Meghalaya works.

Try it first, then show the solutionSolution

1. Bamboo pipes divert water from perennial springs on hilltops to the lower reaches by gravity (1)
2. Bamboo channel sections take water to the plant site and divide it into branches; the flow is controlled by changing pipe positions, and pipes are raised high where they cross a road (1)
3. Reduced channel sections and diversion units drop water near the roots; about 18-20 litres entering the system is reduced to 20-80 drops per minute at the plant (1)

Answer: Bamboo pipes bring water from perennial hilltop springs down the slopes by gravity. Bamboo channels carry it to the plant site and divide it into branches. The flow is controlled by moving the pipes, and pipes are raised where they cross roads. Finally, small channel sections drop water near the roots. About 18-20 litres is reduced to 20-80 drops per minute.

Water Resources in real life

Each concept, met in an everyday situation. Read the situation, answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Topics in this chapter

• Water Scarcity and Need for Water Conservation
• Multipurpose River Projects
• Rainwater Harvesting
• Bamboo Drip Irrigation SystemComing soon
• Water Resources Map Work: DamsComing soon

Water Resources: key facts

Why water is renewable

Water moves through the hydrological cycle, so freshwater is continually renewed and recharged.

Opening line for any question on water as a resource or on renewability.

Main cause of water scarcity

In most cases: over-exploitation, excessive use and unequal access among social groups, not just low rainfall.

Use in every 'causes of scarcity' answer before listing factors.

Largest consumer of water

Irrigated agriculture is the largest consumer of water.

MCQs and reasons for over-exploitation of groundwater.

Qualitative scarcity

Enough water exists but it is polluted by domestic and industrial wastes, chemicals, pesticides and fertilisers.

Water pollution questions and the 'region with high rainfall but polluted water' type of item.

Need for conservation

Protect health, ensure food security, sustain livelihoods and productive activities, prevent ecosystem degradation.

Ready four-point answer for 'why conserve water'.

Dam

A barrier across flowing water that obstructs, directs or retards flow, often creating a reservoir; has a spillway or weir.

Definition questions and 1-mark MCQs.

Classification of dams

By structure: timber, embankment, masonry. By height: large and major, or low, medium and high.

MCQs on types of dams.

Multi-purpose project

Type	dam whose water serves many uses together
Water uses	irrigation, power, domestic and industrial supply
Other uses	flood control, recreation, inland navigation, fish breeding

Advantages part of any 'evaluate dams' answer.

Bhakra-Nangal

Sutluj-Beas basin; hydel power and irrigation. Map list item.

MCQs, matching and map location.

Hirakud (Hirakund on the map list)

Mahanadi basin; conservation of water with flood control.

MCQs, matching and map location.

Sardar Sarovar

On the Narmada in Gujarat; covers Maharashtra, Madhya Pradesh, Gujarat and Rajasthan; serves drought-prone and desert areas.

Case-based passages and map questions.

Temples of modern India

Jawaharlal Nehru's name for dams: they would integrate agriculture and the village economy with industrialisation and urban growth.

Reason-based and assertion-reason questions.

Krishna-Godavari dispute

Karnataka and Andhra Pradesh objected to Maharashtra diverting more water at Koyna, reducing downstream flow.

Questions on inter-state water disputes and conflicts over dams.

Traditional harvesting by region

Guls or kuls: Western Himalayas; inundation channels: Bengal; khadins: Jaisalmer; johads: other parts of Rajasthan.

Matching, MCQs and 'suggest a method for a region' questions.

Tankas

Underground tanks in Bikaner, Phalodi and Barmer, fed from sloping roofs; stored rainwater is called palar pani.

5-mark description of harvesting in semi-arid Rajasthan.

Bamboo drip irrigation

Meghalaya; 200-year-old; 18-20 litres reduced to 20-80 drops per minute at the plant.

MCQs on the state, and 2- or 5-mark answers that describe the process.

Water Resources: map work

The places on the official CBSE map list for this chapter. Find each one on an outline map of India and practise marking it.

How the board asks Water Resources

The question patterns to expect, and the method that works for each.

Tricks to remember Water Resources

Short memory aids. Say each one aloud once, then use it on a question the same day.

• Causes of quantity scarcity: PIIUU

  Population, Irrigation, Industrialisation, Urbanisation, Unequal access.

  Use it when: Gives you five points at once for a 3- or 5-mark 'causes of scarcity' answer.

• Uses of multi-purpose dams: FRIEND + Fish

  Flood control, Recreation, Irrigation, Electricity, Navigation (inland), Domestic and industrial supply, plus Fish breeding.

  Use it when: Lists all seven uses for the advantages side of an evaluation.

• Dam pairs: B for Both, H for Holds floods

  Bhakra-Nangal does Both jobs (power and irrigation) on the Sutluj-Beas. Hirakud Holds floods back on the Mahanadi. Sardar Sarovar Serves the dry west from the Narmada.

  Use it when: Stops you mixing up dams and basins in MCQs and map clues.

• Region to method ladder

  Hills: Kuls. Bengal: flood channels. Jaisalmer: Khadins. Rest of Rajasthan: Johads. Bikaner-Phalodi-Barmer: Tankas.

  Use it when: Quick choice for 'suggest a method for this region' questions.

• Bucket to drops

  Meghalaya bamboo: 200 years old, 18-20 litres in, 20-80 drops per minute out.

  Use it when: Recall the state and figures for bamboo drip MCQs and process answers.

• Evaluate means two sides

  Benefits, then Problems, then a one-line Balance: B-P-B.

  Use it when: Shapes any 5-mark 'evaluate' or 'examine' answer on dams.

Water Resources: board-level solved questions

Ordered from board level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section E style)

Read the situation, then answer every part. In the board paper this is a 4-mark question split into 1 + 1 + 2 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Water Resources

The slips examiners see most often, and what to write instead.

• ✗Mistake: Blaming scarcity only on low rainfall

  The image of deserts and matkas sticks, so students forget the human causes NCERT stresses.

  Wrong working

  Water scarcity occurs because some regions of India get very little rainfall.

  Right working

  Water scarcity is mostly caused by over-exploitation, excessive use and unequal access among social groups. Population growth, irrigation, industries and urbanisation raise demand, so even areas with ample water face scarcity.

  ✓Do this: Open every scarcity answer with the human causes, and mention rainfall only as variation over space and time.

  Usually costs: 1 mark in a 2-mark answer, more in a 5-mark one

• ✗Mistake: Mixing up Bhakra-Nangal and Hirakud

  Both are named examples in the same paragraph and are learnt together.

  Wrong working

  Hirakud in the Sutluj-Beas basin is used for hydel power and irrigation.

  Right working

  Bhakra-Nangal (Sutluj-Beas basin) is used for hydel power and irrigation. Hirakud (Mahanadi basin) integrates conservation of water with flood control.

  ✓Do this: Use the 'B for Both, H for Holds floods' trick and say it aloud once.

  Usually costs: 1 mark in an MCQ, or a full map mark

• ✗Mistake: Writing only advantages in an 'evaluate' question

  Students think 'temples of modern India' means dams are simply good.

  Wrong working

  Multi-purpose projects give irrigation, electricity, water supply, flood control and fish breeding, so they are very useful.

  Right working

  Dams provide irrigation, power, water supply and flood control. But they disturb sediment flow, fragment rivers, submerge land, have triggered floods, induced earthquakes and caused salinisation. Their benefits must be weighed against these costs.

  ✓Do this: In any 'evaluate' or 'examine' question, write both sides and end with a balanced line.

  Usually costs: 2 to 3 marks in a 5-mark answer

• ✗Mistake: Reversing the Indira Gandhi Canal effect

  Students assume more water means more harvesting.

  Wrong working

  Rooftop rainwater harvesting has become popular in western Rajasthan because of the Indira Gandhi Canal.

  Right working

  In western Rajasthan, rooftop harvesting is declining because the perennial Indira Gandhi Canal supplies plenty of water, though some houses keep tankas because they dislike the taste of tap water.

  ✓Do this: Remember: canal water arrived, so tanka use fell.

  Usually costs: 1 mark in an assertion-reason or correct-the-statement item

• ✗Mistake: Saying the first rain is collected in tankas

  Students think every drop must be saved.

  Wrong working

  All rainwater from the first shower is stored in the tanka.

  Right working

  The first spell of rain is not collected because it cleans the roofs and pipes; water from the later showers is stored.

  ✓Do this: Link the rule to its reason, cleaning, so you remember both.

  Usually costs: 1 mark in a 5-mark description

• ✗Mistake: Assuming high rainfall means no scarcity

  Students do not apply the 'ample water but still scarce' idea to examples.

  Wrong working

  Shillong has no water problem because Cherapunjee and Mawsynram nearby get the highest rainfall in the world.

  Right working

  Despite being 55 km from the places with the world's highest rainfall, Shillong faces acute water shortage, so nearly every household harvests rooftop rainwater.

  ✓Do this: Treat Shillong as the key example that rainfall nearby does not equal water at home.

  Usually costs: 1 to 2 marks in a case-based part

• ✗Mistake: Writing long paragraphs beyond the word limit

  Students write everything they remember instead of value points.

  Wrong working

  A 100-word paragraph for a 2-mark question with the main points buried in the middle.

  Right working

  Two short points of about 20 words each, one idea per point, within 40 words.

  ✓Do this: Count your points against the marks before writing: 2 marks means 2 clear points, 5 marks means 5.

  Usually costs: Lost time, and marks when points are unclear to the examiner

NCERT exercise guide: Water Resources

What each exercise in the NCERT chapter tests, how to approach it, and a question of the same kind solved step by step. Questions here are written in our own words.

Water Resources: previous year questions

• Asked in 19 of the 21 board papers we hold (2023 to 2026), on average 3.5 marks per paper; 28 questions in all, counting OR alternatives. In 4 of 4 sample papers.

Counted from the real papers on our previous year papers page, not estimated. Average marks are over every board paper we hold, with an OR pair counted once. Chapter tags are ours.

Solved board questions from Water Resources

Real questions from recent papers. Try each one first, then open our step-by-step solution with marks per step.

Every Water Resources question, by year

Practice questions on Water Resources

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQBoard level

   In the bamboo drip irrigation system of Meghalaya, about 18-20 litres of water enters the pipes. How much reaches the plant site?
   (a) 18-20 litres per minute
   (b) 20-80 drops per minute
   (c) 200 drops per second
   (d) 2-8 litres per hour

   Hint

   The system is a 'drip' system, so think in drops.

   Answer

   (b) 20-80 drops per minute. The flow is cut down step by step until water drips near the roots.

2. Q2 · 2 marks · Very short answerBoard level

   What is a dam? What is the purpose of a spillway or weir in a dam? (2 marks)

   Hint

   One point for the barrier, one for the section water flows over.

   Answer

   A dam is a wall-like structure built across a river to hold back or guide its water, usually forming a reservoir behind it (1). The spillway or weir is the section over or through which water is allowed to pass, now and then or all the time (1).

3. Q3 · 1 mark · MCQBoard level

   Which state is the first in India to make rooftop rainwater harvesting structures compulsory for all houses?
   (a) Rajasthan
   (b) Meghalaya
   (c) Karnataka
   (d) Tamil Nadu

   Hint

   This state also has legal provisions to punish defaulters.

   Answer

   (d) Tamil Nadu. It has made rooftop harvesting compulsory for all houses, with legal provisions to punish defaulters.

4. Q4 · 1 mark · Assertion-reasonHarder board level

   Assertion (A): Multi-purpose projects have added to land degradation in floodplains.
   Reason (R): Sedimentation in reservoirs deprives floodplains of silt, a natural fertiliser.
   (a) Both A and R are true and R is the correct explanation of A.
   (b) Both A and R are true but R is not the correct explanation of A.
   (c) A is true but R is false.
   (d) A is false but R is true.

   Hint

   Ask whether losing silt would cause the land degradation.

   Answer

   (a) Both are true. Silt stays behind the dam, so floodplains lose their natural fertiliser and the land degrades.

5. Q5 · 2 marks · Very short answerBoard level

   What is the cause of the Krishna-Godavari dispute? Why do the downstream states object? (2 marks)

   Hint

   Think of which state diverts water, where, and who suffers.

   Answer

   Maharashtra planned to divert more water at Koyna for a multipurpose project, and Karnataka and Andhra Pradesh objected. Less water would then flow downstream into their states, which would hurt their agriculture and industry.

6. Q6 · 2 marks · Very short answerBoard level

   State two broad objectives of the Pradhan Mantri Krishi Sinchayee Yojana. (2 marks)

   Hint

   Remember the two slogans in the textbook.

   Answer

   • Bring water physically to every farm and expand the area under assured irrigation ('har khet ko pani').
   • Raise on-farm water use efficiency and spread water-saving technology to cut waste ('per drop more crop').

7. Q7 · 5 marks · Long answerHarder board level

   Why are dams now called multi-purpose projects? Explain with examples how such projects support India's water needs, and state two problems they create. (5 marks)

   Hint

   Give the meaning, list the uses, give two or three named projects, then two problems.

   Answer

   Dams were built for irrigation but now serve many integrated uses: power, domestic and industrial water, flood control, recreation, navigation and fish breeding.

   • Bhakra Nangal (Sutluj-Beas basin) gives hydel power and irrigation.
   • Hirakud (Mahanadi basin) combines conservation with flood control.
   • Sardar Sarovar (Narmada) brings water to drought-prone Gujarat and Rajasthan.

   Problems: rivers are fragmented, which harms fish migration, and sedimentation can trigger floods.

8. Q8 · 2 marks · Map workHarder board level

   On an outline map of India, locate and label (i) Rana Pratap Sagar Dam and (ii) Tungabhadra Dam. Name the state where each lies. (2 marks)

   Hint

   One is in Rajasthan, the other in the south.

   Answer

   (i) Rana Pratap Sagar: on the Chambal river in south-eastern Rajasthan.
   (ii) Tungabhadra: on the Tungabhadra river in Karnataka. Mark each with a dam symbol and label it.

9. Q9 · 2 marks · Very short answerHOTS / competency

   Suppose a city receives very heavy rain each monsoon, yet faces acute water shortage every summer. Suggest two measures and justify each. (2 marks)

   Hint

   Heavy rain is wasted if it is not stored. Look at what Shillong households do.

   Answer

   • Rooftop rainwater harvesting in every house: monsoon rain is stored instead of running off, as Shillong households do to meet part of their needs.
   • Overflow sent to wells or old dugwells: it recharges groundwater, which can be drawn in summer.

10. Q10 · 2 marks · Very short answerHOTS / competency

    One household in Phalodi had a tanka 6.1 metres deep, 4.27 metres long and 2.44 metres wide. Roughly how many litres could it hold (1 cubic metre = 1,000 litres)? Why did such tankas make drinking water reliable? (2 marks)

    Hint

    Multiply the three sides, then convert to litres.

    Answer

    Volume = 6.1 × 4.27 × 2.44 ≈ 63.6 cubic metres, or about 63,600 litres (1). Rain stored in the tanka lasted till the next rainfall, so the family had drinking water in summer even when other sources had dried up (1).

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.Which activity is the largest consumer of water?Show answer

   Irrigated agriculture.

2. 2.Bhakra-Nangal lies in which river basin and serves which two purposes?Show answer

   The Sutluj-Beas basin; hydel power production and irrigation.

3. 3.Who called dams the 'temples of modern India'?Show answer

   Jawaharlal Nehru.

4. 4.What are guls or kuls?Show answer

   Diversion channels of the Western Himalayas used for agriculture.

5. 5.What is palar pani?Show answer

   The local name for rainwater in the tanka areas of Rajasthan, considered the purest form of natural water.

6. 6.Which state first made rooftop rainwater harvesting compulsory for all houses?Show answer

   Tamil Nadu.

7. 7.In the bamboo drip system, how much water enters and how much reaches the plant?Show answer

   About 18-20 litres enters the pipes, reduced to 20-80 drops per minute at the plant.

8. 8.Which states objected in the Krishna-Godavari dispute, and why?Show answer

   Karnataka and Andhra Pradesh, because Maharashtra planned to divert more water at Koyna, reducing downstream flow.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Can you explain in two lines why water is renewable but can still be scarce?
• ☐Can you list five human causes of water scarcity with one effect each?
• ☐Can you name four pollutants that make water hazardous, and four reasons to conserve water?
• ☐Can you give three ancient examples of hydraulic structures with their places or centuries?
• ☐Can you list the seven uses of a multi-purpose project and match Bhakra-Nangal and Hirakud to their basins and purposes?
• ☐Can you explain how dams built to control floods have triggered floods?
• ☐Can you match guls or kuls, inundation channels, khadins, johads and tankas to their regions?
• ☐Can you describe the tanka system, including why the first rain is not collected?
• ☐Can you state the Shillong, Gendathur and Tamil Nadu examples in one line each?
• ☐Can you mark Salal, Bhakra Nangal, Tehri, Rana Pratap Sagar, Sardar Sarovar, Hirakund, Nagarjun Sagar and Tungabhadra on a blank map?

Water Resources: frequently asked questions