Water Resources, Class 12 Geography

What Water Resources is about

Weightage: India: People and Economy, Unit III: Resources and Development carries 10 of the 70 theory marks; this chapter shares them with Land Resources and Agriculture, Mineral and Energy Resources and Planning and Sustainable Development in Indian Context.Source: CBSE Geography (029) syllabus 2026-27, course structure

Key concepts

Surface water resources

NCERT section Surface Water Resources

Four sources: rivers, lakes, ponds and tanks. India has about 10,360 rivers and tributaries longer than 1.6 km.

• Mean annual flow in all river basins: about 1,869 cubic km; but only about 690 cubic km (32 per cent) of surface water can be used, because of topographical, hydrological and other limits.
• River flow depends on the size of the catchment area and rainfall within it. Precipitation varies greatly over space and is concentrated in the monsoon.
• The Ganga, Brahmaputra and Barak have high catchment rainfall: though about one-third of the country's area, they hold 60 per cent of surface water.
• Much of the flow of south Indian rivers (Godavari, Krishna, Kaveri) has been harnessed; this is yet to be done in the Brahmaputra and Ganga basins.

Worked example

Why do the Ganga, Brahmaputra and Barak basins have the largest surface water resources? (3 marks)

Try it first, then show the solutionSolution

1. River flow depends on the size of the catchment area and rainfall within it.
2. These rivers have huge catchments with relatively high precipitation.
3. So although they cover only about one-third of India's area, they hold about 60 per cent of its surface water.

Answer: Large catchments with high rainfall give them 60 per cent of surface water.

Groundwater, lagoons and backwaters

NCERT section Groundwater Resources; Lagoons and Backwaters

Groundwater: total replenishable groundwater is about 432 cubic km.

• Utilisation is high in river basins of the north-west and parts of the south: very high in Punjab, Haryana, Rajasthan and Tamil Nadu.
• Low utilisation: Chhattisgarh, Odisha, Kerala use only a small share of potential.
• Moderate: Gujarat, Uttar Pradesh, Bihar, Tripura, Maharashtra.
• If trends continue, demand will need more supply than available, harming development and possibly causing social upheaval.

Lagoons and backwaters: India's vast, indented coastline has many lagoons and lakes; Kerala, Odisha and West Bengal have large surface water in them. Though usually brackish, the water is used for fishing and irrigating certain varieties of paddy and coconut.

Worked example

Which states have very high groundwater utilisation and why? (3 marks)

Try it first, then show the solutionSolution

1. Punjab, Haryana, Rajasthan and Tamil Nadu have very high groundwater utilisation.
2. In Punjab and Haryana, intensive irrigated farming of wheat and rice relies heavily on wells and tubewells (76.1 per cent and 51.3 per cent of net irrigated area).
3. Low rainfall or seasonal dryness and the needs of water-intensive crops push farmers to draw groundwater, leading to depletion.

Answer: Punjab, Haryana, Rajasthan, Tamil Nadu: intensive irrigation and well-based water use.

Water demand and utilisation

NCERT section Water Demand and Utilisation

India has been an agrarian economy with about two-thirds of people dependent on agriculture, so irrigation got high priority in the Five Year Plans, with multipurpose projects like Bhakra-Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar and the Indira Gandhi Canal. Water demand is dominated by irrigation.

Shares of utilisation:

Sector	Surface water	Groundwater
Agriculture	89%	92%
Industry	2%	5%
Domestic	9%	lower than in surface water

In future, with development, the shares of industrial and domestic sectors are likely to increase.

Worked example

Why is the share of agriculture in total water use expected to decline in future? (3 marks)

Try it first, then show the solutionSolution

1. Agriculture currently uses 89 per cent of surface water and 92 per cent of groundwater.
2. With development, industries and urban households will need much more water.
3. So the shares of industrial and domestic sectors are likely to rise, reducing agriculture's relative share.

Answer: Because growing industrial and domestic demand will take a larger share.

Demand of water for irrigation

NCERT section Demand of Water for Irrigation

Why irrigation is needed:

• Spatio-temporal variability of rainfall; large tracts (north-western India, Deccan plateau) are rain-deficient and drought-prone.
• Winter and summer are largely dry in most of the country.
• Even in rainy West Bengal and Bihar, monsoon breaks or failure create dry spells.
• Crops like rice, sugarcane and jute need a lot of water.
• Irrigation makes multiple cropping possible; irrigated land is more productive; HYVs need regular moisture: hence the Green Revolution succeeded in Punjab, Haryana and western UP.

Over-use:

• In Punjab, Haryana and western UP, over 85 per cent of net sown area is irrigated; wells and tubewells irrigate 76.1% (Punjab) and 51.3% (Haryana) of net irrigated area, causing groundwater depletion and a falling water table.
• Over-withdrawal has raised fluoride in groundwater in Rajasthan and Maharashtra and arsenic in parts of West Bengal and Bihar.
• Intensive irrigation increases soil salinity.

PMKSY (2015-16): Pradhan Mantri Krishi Sinchayee Yojana: protective irrigation for all farms. Objectives: 'Har khet ko pani' (more area under assured irrigation); integrate water source, distribution and efficient use; improve on-farm efficiency, 'Per drop more crop'; sustainable conservation; integrated development of rainfed areas through the watershed approach.

Worked example

What factors are responsible for the highest groundwater development in Punjab, Haryana and Tamil Nadu? (3 marks)

Try it first, then show the solutionSolution

1. Agriculture in these states depends on assured irrigation for water-intensive crops like rice and wheat and for HYVs that need regular moisture.
2. Wells and tubewells irrigate a large share of the net irrigated area (76.1 per cent in Punjab, 51.3 per cent in Haryana).
3. Rainfall is limited or seasonal, so farmers rely heavily on groundwater, leading to over-use and a falling water table.

Answer: Intensive irrigated farming of water-hungry crops through wells and tubewells.

Emerging water problems: deteriorating quality

NCERT section Emerging Water Problems; Deterioration of Water Quality

Per capita water availability is dwindling as population grows, and water is being polluted by industrial, agricultural and domestic effluents, further limiting usable water.

Water quality means purity of water, free of unwanted foreign substances. Water is polluted by micro-organisms, chemicals, industrial and other wastes, making it unfit for use. Toxic substances entering lakes, streams, rivers and oceans dissolve or remain suspended, degrading quality and aquatic systems; pollutants can seep down into groundwater.

Effects on people (exercise): drinking contaminated water can spread disease and harm health (e.g. fluoride and arsenic contamination noted in the chapter).

Worked example

Discuss the factors responsible for depletion of water resources in India. (3 marks)

Try it first, then show the solutionSolution

1. Population growth increases demand and reduces per capita availability.
2. Over-use of groundwater for irrigation in states like Punjab and Haryana lowers the water table.
3. Pollution by industrial, agricultural and domestic effluents makes water unusable, further reducing availability.

Answer: Rising demand, over-extraction and pollution.

Prevention of water pollution and recycling

NCERT section Water Conservation and Management; Prevention of Water Pollution; Recycle and Reuse of Water

Need for conservation: freshwater is declining and demand rising; desalinisation is costly, so sea water is negligible as a source. India needs policies, laws, water-saving technologies, pollution prevention, watershed development, rainwater harvesting, recycling and reuse, and conjunctive use of water.

Prevention of water pollution:

• Rivers keep better quality in less populated upper hilly stretches; in the plains they are used intensively, and drains bring agricultural (fertilisers, insecticides), domestic and industrial effluents. Pollution is highest in summer when flow is low.
• The Central Pollution Control Board (CPCB) with State Boards monitors water quality at 507 stations: organic and bacterial contamination is the main source of river pollution.
• Most polluted: the Yamuna between Delhi and Etawah. Others: Sabarmati at Ahmedabad, Gomti at Lucknow, Kali, Adyar, Cooum (entire stretches), Vaigai at Madurai, Musi at Hyderabad, and the Ganga at Kanpur and Varanasi.
• Groundwater is polluted by heavy/toxic metals, fluoride and nitrates.
• Laws such as the Environment Protection Act 1986 and the Water (Prevention and Control of Pollution) Act 1974 were poorly implemented (in 1997, 251 polluting industries were along rivers and lakes); the Water Cess Act 1977 had marginal impact. Public awareness is needed.

Recycle and reuse:

• Industries can use reclaimed wastewater for cooling and fire-fighting, cutting costs.
• In cities, water from bathing and washing utensils or vehicles can be used for gardening, saving better water for drinking.
• Recycling is limited at present, with enormous scope.

Worked example

Why is river water pollution high in the plains and in summer? Name two severely polluted rivers. (3 marks)

Try it first, then show the solutionSolution

1. In the plains, river water is used intensively, and drains carrying fertilisers, insecticides, domestic waste and industrial effluents join the rivers.
2. In summer the flow is low, so pollutants become highly concentrated.
3. Severely polluted: the Yamuna between Delhi and Etawah (most polluted), the Sabarmati at Ahmedabad, the Gomti at Lucknow, the Ganga at Kanpur and Varanasi (any two).

Answer: Intensive use and effluents in plains, low summer flow; e.g. Yamuna and Sabarmati.

Watershed management and rainwater harvesting

NCERT section Watershed Management; Rainwater Harvesting

Watershed management: efficient management and conservation of surface and groundwater: preventing runoff, storing water and recharging groundwater (percolation tanks, recharge wells). Broadly, it includes conservation, regeneration and judicious use of all natural and human resources in a watershed, balancing nature and society. Success depends on community participation.

• Haryali: Central Government watershed project helping rural people conserve water for drinking, irrigation, fisheries and afforestation, executed by Gram Panchayats with people's participation.
• Atal Bhujal Yojana (Atal Jal): in 8,220 water-stressed Gram Panchayats of 229 blocks in 80 districts of seven states (Gujarat, Haryana, Karnataka, MP, Maharashtra, Rajasthan, UP), which hold about 37 per cent of India's water-stressed blocks; aims at behavioural change from consumption to conservation.
• Neeru-Meeru (Water and You) in Andhra Pradesh and Arvary Pani Sansad in Alwar, Rajasthan built percolation tanks, johads, check dams with people's participation. Tamil Nadu made rainwater harvesting structures compulsory in houses.
• Only a few success stories; many programmes are nascent, needing awareness.

Case study: Ralegan Siddhi (Ahmadnagar, Maharashtra): in 1975 the village was poor with illicit liquor trade. A retired army man led watershed development, persuading villagers on family planning, voluntary labour, no open grazing, no tree felling, and prohibition. Repairing a leaking percolation tank filled seven wells in summer. A youth group (Tarun Mandal) fought dowry, caste discrimination and untouchability; stall-feeding; ban on sugarcane (water-intensive) in favour of low-water crops; consensus elections; Nyay Panchayats; a Rs 22 lakh school built with village resources. Water is now adequate and farming flourishes (though fertiliser and pesticide use is high).

Rainwater harvesting: capturing and storing rain for use and to recharge aquifers; low-cost and eco-friendly. Benefits: more water, checks falling water table, dilutes contaminants like fluoride and nitrates, prevents soil erosion and flooding, arrests salt-water intrusion in coastal areas. Traditional methods: lakes, ponds, tanks; in Rajasthan, kund or tanka (covered underground tank). Rooftop harvesting reduces dependence on groundwater and saves pumping energy; especially useful in cities.

Other remedies: desalinisation in coastal areas, inter-linking of rivers, and above all pricing of water.

Worked example

What is watershed management? Can it play an important role in sustainable development? (5 marks)

Try it first, then show the solutionSolution

1. Watershed management is the efficient management and conservation of surface and groundwater: preventing runoff, storing water and recharging groundwater through percolation tanks and recharge wells.
2. Broadly it conserves, regenerates and judiciously uses all natural and human resources in a watershed, balancing nature and society.
3. Its success depends on community participation, as in Haryali (Gram Panchayats), Neeru-Meeru (Andhra Pradesh) and Arvary Pani Sansad (Alwar).
4. Ralegan Siddhi shows how voluntary labour, a percolation tank, banning water-intensive crops and social reform brought adequate water and prosperity.
5. So yes: by conserving water for future generations while supporting livelihoods, it promotes sustainable development, though awareness must spread as success stories are still few.

Answer: Community-based conservation of water and land in a watershed; it is key to sustainable development.

National policies and campaigns

NCERT section National Water Policy 2012; Jal Kranti Abhiyan

National Water Policy 2012: assesses the situation and proposes a unified national action framework. Highlights:

• Need for a national water framework law and legislation for inter-State rivers.
• After pre-emptive needs (safe drinking water and sanitation, food security, poor farmers' livelihoods, minimum eco-system needs), water to be treated as an economic good to promote conservation and efficiency.
• Climate change adaptation in designing water structures.
• Benchmarks (water footprints) and water auditing for efficient use.
• Removing the large urban-rural disparity in water supply norms.
• Community participation in water projects.

Jal Kranti Abhiyan (2015-16): aims at water security through per capita availability, involving local bodies, NGOs and citizens. Activities:
1. One water-stressed village in each of 672 districts to become a 'Jal Gram'.
2. Model command areas of about 1,000 ha in different regions.
3. Pollution abatement: conservation and artificial recharge, reducing groundwater pollution, arsenic-free wells.
4. Mass awareness through media and school competitions.
It seeks livelihood and food security through water security.

Worked example

State any three highlights of the National Water Policy 2012. (3 marks)

Try it first, then show the solutionSolution

1. Need for a national water framework law and legislation for inter-State rivers.
2. After meeting needs like drinking water, sanitation and food security, water should be treated as an economic good to promote conservation and efficient use.
3. Water footprints and auditing, climate change adaptation, reducing urban-rural disparity and community participation (any).

Answer: Framework law, water as an economic good after basic needs, and water auditing and community participation.

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

• Surface Water, Groundwater and Water Demand
• Deterioration of Water Quality and Its Prevention
• Water Conservation, Rainwater Harvesting and Watershed Management

Water Resources: key facts

India's share

2.45% of world area; 4% of water; >17% of population

Freshwater ~3% of earth's water.

India's water budget

Precipitation ~4,000 cu km; surface + groundwater 1,869 cu km; usable 1,122 cu km (60%)

Surface usable 690 cu km (32%).

Surface water

10,360 rivers > 1.6 km; Ganga-Brahmaputra-Barak: 1/3 area, 60% surface water

South Indian rivers largely harnessed.

Groundwater

432 cu km replenishable; very high use: Punjab, Haryana, Rajasthan, Tamil Nadu; low: Chhattisgarh, Odisha, Kerala

Moderate: Gujarat, UP, Bihar, Tripura, Maharashtra.

Utilisation shares

$Agriculture89$

Industry and domestic shares to rise.

Irrigation facts

>85% NSA irrigated in Punjab, Haryana, W UP; wells/tubewells 76.1% (Punjab), 51.3% (Haryana)

Fluoride: Rajasthan, Maharashtra; arsenic: WB, Bihar.

PMKSY (2015-16)

Har khet ko pani; Per drop more crop; watershed approach for rainfed areas

Protective irrigation for all farms.

Pollution

CPCB 507 stations; organic and bacterial contamination main; Yamuna (Delhi-Etawah) most polluted

Acts: 1974 Water, 1977 Cess, 1986 Environment.

Watershed programmes

Haryali (Gram Panchayats); Atal Jal (8,220 GPs, 7 states); Neeru-Meeru (AP); Arvary Pani Sansad (Alwar)

Ralegan Siddhi case study.

Rainwater harvesting

Store rain + recharge aquifers; benefits: supply, water table, dilution of fluoride/nitrates, erosion and flood control, stops salt intrusion

Kund/tanka in Rajasthan; compulsory in Tamil Nadu houses.

Policies

National Water Policy 2012; Jal Kranti Abhiyan 2015-16 (Jal Gram in 672 districts)

Pricing of water matters most for users.

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.

• Water budget

  "4000 rain, 1869 available, 1122 usable".

  Use it when: Availability numbers.

• Use shares

  "89-2-9 surface; 92-5 ground".

  Use it when: Sector shares.

• Pollution Acts

  "74 Water, 77 Cess, 86 Environment".

  Use it when: Laws.

• Watershed programmes

  "HANA": Haryali, Atal Jal, Neeru-Meeru, Arvary.

  Use it when: Programmes.

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 3-mark question split into 1 + 1 + 1 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: Mixing up the 1,869, 1,122 and 690 figures

  Several numbers.

  ✓Do this: 1,869: available (surface + groundwater) and also mean river flow; 1,122: total usable; 690: usable surface water.

  Usually costs: 1 mark.

• ✗Mistake: Saying Kerala uses much groundwater

  Southern state confusion.

  ✓Do this: Tamil Nadu is very high; Kerala, Odisha, Chhattisgarh are low.

  Usually costs: 1 mark.

• ✗Mistake: Defining watershed management only as water storage

  Narrow view.

  ✓Do this: Broadly it covers all natural and human resources in a watershed, with community participation.

  Usually costs: 1 mark.

• ✗Mistake: Ignoring legislation when discussing pollution

  Students list only sources.

  ✓Do this: Mention the 1974, 1977 and 1986 Acts and their weak implementation.

  Usually costs: 1 mark in 5-mark answers.

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.

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

   The highest proportion of total water used in India is in:
   (a) Irrigation
   (b) Industries
   (c) Domestic use
   (d) None of these

   Hint

   89% and 92%.

   Answer

   (a).

2. Q2 · 1 mark · MCQBoard level

   What share of India's surface water can be utilised?
   (a) About 60 per cent
   (b) About 32 per cent
   (c) About 17 per cent
   (d) About 89 per cent

   Hint

   690 of 1,869 cubic km.

   Answer

   (b).

3. Q3 · 1 mark · Assertion-reasonHarder board level

   Assertion (A): Groundwater has become contaminated with fluoride in Rajasthan and Maharashtra.
   Reason (R): Over-withdrawal of groundwater has increased fluoride concentration.
   Choose (a)-(d).

   Hint

   Over-use.

   Answer

   (a) Both are true and R explains A.

4. Q4 · 1 mark · MCQHarder board level

   Match:
   i. Neeru-Meeru a. Alwar, Rajasthan
   ii. Arvary Pani Sansad b. Andhra Pradesh
   iii. Atal Jal c. Seven water-stressed states
   iv. Haryali d. Executed by Gram Panchayats
   (a) i-b, ii-a, iii-c, iv-d
   (b) i-a, ii-b, iii-c, iv-d
   (c) i-b, ii-c, iii-a, iv-d
   (d) i-d, ii-a, iii-c, iv-b

   Hint

   Programmes.

   Answer

   (a).

5. Q5 · 3 marks · Short answerBoard level

   What are the benefits of rainwater harvesting? (3 marks)

   Hint

   Six benefits.

   Answer

   It increases water availability, checks the declining groundwater table, improves groundwater quality by diluting fluoride and nitrates, reduces flooding and soil erosion, and, when used to recharge aquifers, stops sea water from entering coastal groundwater. It also reduces dependence on groundwater and saves energy used for pumping.

6. Q6 · 3 marks · Short answerHOTS / competency

   Suppose a village's wells dry up every summer because farmers grow sugarcane with tubewells and rainwater runs off the hills. Using the chapter, suggest a plan to restore water. (3 marks)

   Hint

   Ralegan Siddhi model.

   Answer

   Adopt watershed management with community participation: build percolation tanks, check dams and johads to stop runoff and recharge groundwater; replace water-intensive sugarcane with low-water crops like pulses and oilseeds; stop open grazing and tree felling; use voluntary labour as in Ralegan Siddhi; and use efficient irrigation ('per drop more crop') under PMKSY.

7. Q7 · 3 marks · Short answerHarder board level

   What can be the possible impacts of consuming contaminated water? (3 marks)

   Hint

   Health.

   Answer

   Contaminated water carries micro-organisms, chemicals and wastes that make it unfit for human use; drinking it can cause disease and harm health. The chapter notes groundwater contamination with toxic metals, fluoride, nitrates and arsenic (West Bengal, Bihar), which are harmful to people. Organic and bacterial contamination is the main source of river pollution.

8. Q8 · 5 marks · Long answerHOTS / competency

   Explain the measures for prevention of water pollution in India and why they have had limited success. (5 marks)

   Hint

   Acts, CPCB, awareness.

   Answer

   The CPCB with State Boards monitors water quality at 507 stations, finding organic and bacterial contamination the main problem; the Yamuna (Delhi-Etawah), Sabarmati, Gomti, Kali, Adyar, Cooum, Vaigai, Musi and Ganga at Kanpur and Varanasi are badly polluted. Laws include the Water (Prevention and Control of Pollution) Act 1974, Water Cess Act 1977 and Environment Protection Act 1986. But they were not implemented effectively (251 polluting industries along rivers and lakes in 1997), and the Cess Act had marginal impact. Effluents from agriculture, homes and industry still enter rivers, especially in the plains. Public awareness and action, recycling, and treating water as an economic good can help reduce pollution.

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.What share of the earth's water is freshwater?Show answer

   About 3 per cent.

2. 2.How many rivers in India are longer than 1.6 km?Show answer

   About 10,360 rivers and tributaries.

3. 3.What is the total replenishable groundwater in India?Show answer

   About 432 cubic km.

4. 4.At how many stations does the CPCB monitor water quality?Show answer

   507.

5. 5.What is a kund or tanka?Show answer

   A covered underground tank for storing harvested rainwater in Rajasthan.

6. 6.When was the Jal Kranti Abhiyan launched?Show answer

   In 2015-16.

Quick revision checklist

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

• ☐Can you give India's share of world water and population?
• ☐Can you state total, available and usable water figures?
• ☐Can you explain why the Ganga-Brahmaputra-Barak hold 60% of surface water?
• ☐Can you classify states by groundwater use?
• ☐Can you give sectoral water-use shares?
• ☐Can you explain why irrigation is needed and its side effects?
• ☐Can you name the most polluted rivers and pollution laws?
• ☐Can you explain recycling and reuse?
• ☐Can you describe watershed programmes and Ralegan Siddhi?
• ☐Can you list the benefits of rainwater harvesting?

Water Resources: frequently asked questions