GeographyCBSE Class 12 · Water Resources

Surface Water, Groundwater, Lagoons and Water Demand in India (Class 12 Geography, India: People and Economy, Chapter 4)

Updated 16 October 2026 · Fact-checked

India has about 4 per cent of the world's water resources against more than 17 per cent of its population. Of 1,869 cubic km of surface water and replenishable groundwater, only 1,122 cubic km is utilisable. Agriculture takes 89 per cent of surface water and 92 per cent of groundwater used, so irrigation dominates demand.

Follow the funnel: only 60% of the 1,869 km³ available is usable, and the 1,122 km³ is surface 690 plus groundwater 432.

Illustration drawn for QuestionBuddy.

Understand Surface Water, Groundwater and Water Demand

Why this topic matters. Every number in this section (4,000, 1,869, 1,122, 690, 432) and the sector shares (89, 92, 2, 5, 9) can be tested as data questions. Learn them as a funnel from rainfall to usable water.

1. India's position. About 2.45 per cent of the world's surface area, 4 per cent of its water resources, more than 17 per cent of its population. Water scarcity may be the greatest challenge of the future: demand rises while supply shrinks through over-utilisation and pollution. Freshwater is only about 3 per cent of the world's water.

2. The funnel of numbers.

Precipitation in a year: about 4,000 cubic km.
Availability from surface water and replenishable groundwater: 1,869 cubic km.
Only 60 per cent can be put to beneficial use: utilisable resource = 1,122 cubic km.
Surface water: NCERT says that because of topographical, hydrological and other constraints, "only about 690 cubic km (32 per cent) of the available surface water can be utilised". Replenishable groundwater: about 432 cubic km. The two add up to the utilisable total: 690 + 432 = 1,122.

3. Surface water.

Four sources: rivers, lakes, ponds and tanks. About 10,360 rivers and tributaries are longer than 1.6 km; mean annual flow is 1,869 cubic km.
Utilisation is limited by topography, hydrology and other constraints.
Flow depends on catchment area and rainfall in it. The Ganga, Brahmaputra and Barak basins cover about one-third of the area but hold 60 per cent of surface water.
Much of the flow of the Godavari, Krishna and Kaveri is already harnessed; the Brahmaputra and Ganga basins are yet to be.

4. Groundwater.

Total replenishable: about 432 cubic km.
Utilisation high in the north-western river basins and parts of south India: Punjab, Haryana, Rajasthan, Tamil Nadu.
Moderate: Gujarat, Uttar Pradesh, Bihar, Tripura, Maharashtra. Small proportion used: Chhattisgarh, Odisha, Kerala.
If present trends continue, demand will outstrip supply, harming development and risking social upheaval.

5. Lagoons and backwaters. India has a long, indented coast, so many lagoons and lakes formed; Kerala, Odisha and West Bengal have vast resources. Water is generally brackish, but is used for fishing and for irrigating certain varieties of paddy and coconut.

6. Water demand and utilisation.

About two-thirds of the population depends on agriculture, so irrigation development had very high priority in Five Year Plans (Bhakra-Nangal, Hirakud, Damodar Valley, Nagarjuna Sagar, Indira Gandhi Canal).
Agriculture: 89 per cent of surface water and 92 per cent of groundwater utilisation. Industry: 2 per cent of surface and 5 per cent of groundwater. Domestic: 9 per cent of surface water, higher than its share of groundwater. Industrial and domestic shares are likely to rise with development.
Irrigation is needed because of spatio-temporal variability of rainfall: much of India is deficient in rainfall and drought-prone (north-western India and the Deccan plateau); winter and summer are mostly dry; monsoon breaks cause dry spells even in West Bengal and Bihar. Rice, sugarcane and jute need much water. Irrigation allows multiple cropping, higher productivity and success of HYVs.
In Punjab, Haryana and western Uttar Pradesh more than 85 per cent of net sown area is irrigated; 76.1 per cent (Punjab) and 51.3 per cent (Haryana) of net irrigated area is by wells and tubewells, so the water table is falling. Over-withdrawal raised fluoride in parts of Rajasthan and Maharashtra and arsenic in parts of West Bengal and Bihar.

7. Pradhan Mantri Krishi Sinchayee Yojana (2015-16). Aims at protective irrigation for every farm (Har khet ko pani), more crop per drop, integration of source, distribution and efficient use, sustainable conservation and integrated development of rainfed areas.

Graph checklist. Draw a funnel: 4,000 -> 1,869 -> 1,122 cubic km, and a bar for sector shares of surface and groundwater.

Key quotations

Short lines worth knowing by heart: who says them, when, and why they matter.

Agriculture accounts for most of the surface and groundwater utilisation, it accounts for 89 per cent of the surface water and 92 per cent of the groundwater utilisation.
NCERT, India: People and Economy, Chapter 4: Section 'Water Demand and Utilisation'.
The two numbers behind nearly every sector-share question.

Surface Water, Groundwater and Water Demand: key facts

Utilisable water funnel: Precipitation 4,000 cubic km
Available 1,869
Utilisable 1,122 (60%); Utilisable = 690 surface + 432 groundwater.
Sector shares of utilisation: $S u r f a ce : a g r i c u l t u r e 89$; NCERT gives the domestic share of groundwater only as lower than 9 per cent.
Groundwater use by state: Very high Punjab, Haryana, Rajasthan, Tamil Nadu
Moderate Gujarat, UP, Bihar, Tripura, Maharashtra
Low Chhattisgarh, Odisha, Kerala; Utilisation as a proportion of potential.
Wells and tubewells in net irrigated area: $P u nj ab 76.1$; Link to groundwater depletion.

Very high	Punjab, Haryana, Rajasthan, Tamil Nadu
Moderate	Gujarat, UP, Bihar, Tripura, Maharashtra
Low	Chhattisgarh, Odisha, Kerala

How to answer Surface Water, Groundwater and Water Demand questions

Data questions on this section need exact figures and a one-line reason. Practise moving from rainfall to utilisable water, and from sector share to cause.

1Write the funnel in order: 4,000, 1,869, 1,122 cubic km, with 60 per cent as the link.
2For a sector share question, state agriculture's 89 and 92 per cent first, then the smaller shares.
3For state-wise groundwater questions, sort states into high, moderate and low use before giving reasons.
4Give the reason for irrigation: spatio-temporal variability of rainfall and water-hungry crops.
5For depletion answers, add one quality problem: fluoride or arsenic.

Surface Water, Groundwater and Water Demand in real life

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

Rainfall to usable water

Suppose a household's roof receives enough rain in a year to fill 4,000 buckets. Gutters spill some, the storage tank holds part, and a tank's cover lets you draw only a fraction for drinking.

Which NCERT figures does this match for the country, and what is the lesson?

Try it first, then show the solutionSolution

Annual precipitation is about 4,000 cubic km.
Available surface water and replenishable groundwater is 1,869 cubic km; only 60 per cent is put to beneficial use.
The utilisable resource is 1,122 cubic km.

Answer: 4,000 cubic km of rain gives 1,869 available and just 1,122 utilisable, so the usable share is much smaller than the rain received.

Memory hook: Rain is not the same as usable water.

Brackish backwater

Suppose a fisher family in coastal Kerala catches fish in a lagoon every morning, and their neighbour irrigates coconut palms with its water.

What kind of water body is this, and what does NCERT say about its water?

Try it first, then show the solutionSolution

Lagoons and lakes formed along the indented coast; Kerala, Odisha and West Bengal have vast resources.
The water is generally brackish, but is used for fishing and for irrigating certain paddy varieties and coconut.

Answer: It is a lagoon or backwater; its brackish water supports fishing and the irrigation of some paddy varieties and coconut.

Memory hook: Salty, but not useless.

Tricks to remember Surface Water, Groundwater and Water Demand

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

4, 17, 2.45
4% of the world's water, more than 17% of its people, 2.45% of its area.
Use it when: India's resource-population gap.
Funnel 4000-1869-1122
Rain, then available, then usable (60%).
Use it when: Water availability sums.
89 and 92
Agriculture takes 89% of surface and 92% of groundwater used.
Use it when: Sector shares.
690 + 432
Surface plus groundwater makes the 1,122.
Use it when: Breakup of utilisable water.

Surface Water, Groundwater and Water Demand: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Domestic share of surface water · 1 mark · MCQBoard level

Which sector's share is 9 per cent of India's surface water utilisation, according to NCERT?
(A) Agriculture
(B) Industry
(C) Domestic
(D) Power generation

Try it first, then show the solutionSolution

NCERT: industry has 2 per cent; the share of the domestic sector is higher (9 per cent) in surface water than in groundwater (1 mark).

Answer: (C) Domestic

Example 2: Lagoons and backwaters: the incorrect statement · 1 mark · MCQHarder board level

Which one of the following statements about lagoons and backwaters in India is NOT correct?
(A) Kerala, Odisha and West Bengal have vast resources in lagoons and lakes.
(B) The water is generally brackish.
(C) The water is used for fishing and for irrigating certain varieties of paddy and coconut.
(D) Their fresh water is the main source of drinking water for north-western states.

Try it first, then show the solutionSolution

(A), (B) and (C) are NCERT statements.
(D) is not: the water is generally brackish and the text links these bodies to the coastal states, not the north-west (1 mark).

Answer: (D)

Example 3: Assertion and reason on utilisable water · 1 mark · Assertion-reasonHarder board level

Assertion (A): The total utilisable water resource of India is much smaller than the water received as annual precipitation.
Reason (R): Of the 1,869 cubic km available from surface water and replenishable groundwater, only 60 per cent can be put to beneficial uses.
(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.

Try it first, then show the solutionSolution

Precipitation is about 4,000 cubic km; utilisable water is 1,122 cubic km.
NCERT says only 60 per cent of the 1,869 cubic km can be put to beneficial use, which explains the small figure (1 mark).

Answer: (A) Both (A) and (R) are true and (R) is the correct explanation of (A).

Example 4: Source-based: who uses the water? · 3 marks · Source-basedHarder board level

Read the data: Agriculture accounts for 89 per cent of surface water and 92 per cent of groundwater utilisation. The share of the industrial sector is 2 per cent of surface water and 5 per cent of groundwater. The share of the domestic sector is 9 per cent of surface water, higher than its share in groundwater.
(i) Of 200 units of groundwater used, how many go to agriculture? (1)
(A) 89 (B) 92 (C) 178 (D) 184
(ii) Which statement is correct about industry? (1)
(A) Industry uses a larger share of groundwater than of surface water
(B) Industry uses a larger share of surface water than of groundwater
(C) Industry has the largest share of both
(D) Industry uses no surface water
(iii) Which sector's share of surface water is higher than its share of groundwater? (1)
(A) Industrial (B) Domestic (C) Agriculture (D) None

Try it first, then show the solutionSolution

(i) 92/100 x 200 = 184, so (D) (1 mark).
(ii) 5 per cent of groundwater against 2 per cent of surface water, so (A) (1 mark).
(iii) Domestic: 9 per cent of surface water, lower share in groundwater, so (B) (1 mark).

Answer: (i) D; (ii) A; (iii) B

Example 5: Why three basins hold most of the surface water · 3 marks · Short answerBoard level

The Ganga, Brahmaputra and Barak basins cover only about one-third of India's area but hold about 60 per cent of its surface water resources. Explain this using NCERT's rule for river flow, and state how far the flow of these basins has been harnessed compared with south Indian rivers. (3 marks)

Try it first, then show the solutionSolution

Water flow in a river depends on the size of its catchment area (river basin) and the rainfall within that catchment (1 mark).
Precipitation is relatively high in the catchment areas of the Ganga, Brahmaputra and Barak, so these basins carry a share of the surface water far larger than their share of area (1 mark).
Much of the annual flow of the Godavari, Krishna and Kaveri has been harnessed, but this is yet to be done in the Brahmaputra and Ganga basins (1 mark).

Answer: River flow depends on the size of the catchment and the rainfall in it. The Ganga, Brahmaputra and Barak catchments receive relatively high precipitation, so with about one-third of the area they hold about 60 per cent of the surface water. Much of the flow of the Godavari, Krishna and Kaveri is already harnessed, while the Brahmaputra and Ganga basins are yet to be harnessed.

Example 6: HOTS: groundwater planning for three kinds of state · 5 marks · Long answerHOTS / competency

NCERT groups states by groundwater use: very high (Punjab, Haryana, Rajasthan, Tamil Nadu), moderate (Gujarat, Uttar Pradesh, Bihar, Tripura, Maharashtra) and small proportion of potential (Chhattisgarh, Odisha, Kerala). Suggest, with reasons from the chapter, what planners should do in each group, and what may happen if the present trend continues. (5 marks)

Try it first, then show the solutionSolution

High-use states: limit withdrawal, recharge groundwater, since over-use lowers the water table and raises fluoride or arsenic problems elsewhere (1 mark).
Moderate-use states: monitor and keep withdrawal within potential (1 mark).
Low-use states: scope to develop more groundwater, as they use only a small proportion of potential (1 mark).
If present trends continue, demand will outrun supply (1 mark).
This would be detrimental to development and could cause social upheaval and disruption (1 mark).

Answer: In Punjab, Haryana, Rajasthan and Tamil Nadu groundwater use is already very high. Planners should limit withdrawal and recharge aquifers; in Punjab and Haryana more than 85 per cent of net sown area is irrigated and large shares come from wells and tubewells, which has depleted the water table, and over-withdrawal has been linked to fluoride in parts of Rajasthan and Maharashtra.

Gujarat, Uttar Pradesh, Bihar, Tripura and Maharashtra use groundwater at a moderate rate, so they should keep use within the replenishable potential, while Chhattisgarh, Odisha and Kerala use only a small proportion of potential and have scope for further careful development.

If the present trend continues, the demand for water will outstrip supplies. NCERT warns that this will be detrimental to development and can cause social upheaval and disruptions.

Where students lose marks in Surface Water, Groundwater and Water Demand

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

Mistake: Writing 1,869 cubic km as the utilisable water
It appears beside 1,122 in the same paragraph.
Wrong working
India's utilisable water is 1,869 cubic km.
Right working
1,869 cubic km is available; only 60 per cent, 1,122 cubic km, is utilisable.
Do this: Say 'available' for 1,869 and 'utilisable' for 1,122.
Usually costs: 1 mark.
Mistake: Swapping surface and groundwater shares
Both involve agriculture, industry and domestic sectors.
Wrong working
Agriculture uses 92 per cent of surface water and 89 per cent of groundwater.
Right working
89 per cent of surface water and 92 per cent of groundwater.
Do this: S89, G92: 'surface 89, ground 92'.
Usually costs: 1 mark.
Mistake: Listing a low-use state as a high-use one
Southern states look alike.
Wrong working
Kerala has very high groundwater utilisation.
Right working
Tamil Nadu is very high; Kerala uses only a small proportion of its potential.
Do this: Use the three-group list.
Usually costs: 1 mark.
Mistake: Calling lagoon water fresh
Backwaters are often described as lakes.
Wrong working
Lagoons give fresh water for drinking.
Right working
The water is generally brackish; it is used for fishing and for irrigating certain paddy varieties and coconut.
Do this: Write 'brackish' with the two uses.
Usually costs: 1 mark.

Exam tips

Write numbers with units: cubic km, per cent. Many marks are lost for a bare figure.
Present the water-availability answer as a funnel with the 60 per cent link; it looks complete in three lines.
For irrigation demand questions, always give the reason (rainfall variability) and an example (Punjab, Haryana, western Uttar Pradesh).
Write the surface-water figure exactly as NCERT prints it: "only about 690 cubic km (32 per cent) of the available surface water can be utilised". Do not replace the 32 per cent with a percentage of your own.
The questions on this page are our own and are checked by meaning against the chapter page; they are not copies of past board items.

Practice questions on Surface Water, Groundwater and Water Demand

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

Q1 · 1 mark · MCQBoard level
NCERT estimates the mean annual flow in all the river basins of India at about:
(A) 4,000 cubic km
(B) 1,869 cubic km
(C) 1,122 cubic km
(D) 690 cubic km
Hint
Precipitation is the largest figure; utilisable figures are smaller.
Answer
(B) 1,869 cubic km.
Q2 · 2 marks · Very short answerHarder board level
India's utilisable water is 1,122 cubic km. If the replenishable groundwater is 432 cubic km, how much is the utilisable surface water, and what is the NCERT figure for it? (2 marks)
Hint
Subtract.
Answer
1,122 - 432 = 690 cubic km, which matches NCERT's figure of about 690 cubic km of utilisable surface water.
Q3 · 1 mark · MCQBoard level
India has about what share of the world's water resources?
(A) 2.45 per cent
(B) 4 per cent
(C) 17 per cent
(D) 3 per cent
Hint
Compare with area and population shares.
Answer
(B) 4 per cent.
Q4 · 3 marks · Short answerHarder board level
Annual precipitation is about 4,000 cubic km, but the utilisable resource is only 1,122 cubic km. Give three reasons from the chapter why much of the water cannot be used. (3 marks)
Hint
Only 60 per cent of 1,869; constraints; rainfall pattern.
Answer
(i) Of the 1,869 cubic km available from surface water and replenishable groundwater, only 60 per cent can be put to beneficial uses. (ii) Because of topographical, hydrological and other constraints, only about 690 cubic km of surface water can be utilised. (iii) Precipitation has very high spatial variation and is mainly concentrated in the monsoon season.
Q5 · 3 marks · Short answerHOTS / competency
Kerala has vast lagoons and backwaters and uses only a small proportion of its groundwater potential. A proposal says Kerala should irrigate all its crops with lagoon water. Evaluate the proposal using NCERT. (3 marks)
Hint
What kind of water is in lagoons, and what is it used for?
Answer
NCERT says lagoon and backwater water is generally brackish; it is used for fishing and for irrigating certain varieties of paddy crops and coconut. NCERT does not present it as a source for other crops, so it cannot be relied on to irrigate all crops. At the same time, NCERT places Kerala among states that use only a small proportion of their groundwater potential, so carefully planned groundwater use is a more suitable source for other crops. The proposal should be limited to the crops NCERT names, with fishing kept as a use of the lagoons.
Q6 · 3 marks · Short answerHOTS / competency
In a river basin, surface water use is 89 units for agriculture, 9 for domestic and 2 for industry. Suppose industry's use doubles to 4 units and the other two stay the same. Find the new percentage share of each sector and say what the change shows about NCERT's remark on future shares. (3 marks)
Hint
New total is 102 units.
Answer
New total = 89 + 9 + 4 = 102 units. Agriculture = 89/102 x 100 = about 87.3 per cent; domestic = 9/102 x 100 = about 8.8 per cent; industry = 4/102 x 100 = about 3.9 per cent. Agriculture's share falls while industry's share rises even though agriculture's actual use is unchanged, which agrees with NCERT's remark that with development the shares of industrial and domestic sectors are likely to increase.

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.What share of the world's surface area does India have?Show answer
About 2.45 per cent.
2.How much of the utilisable resource is groundwater, according to the text's breakup?Show answer
About 432 cubic km (utilisable surface water about 690 cubic km).
3.How many rivers and tributaries in India are longer than 1.6 km each?Show answer
About 10,360.
4.In which year was the Pradhan Mantri Krishi Sinchayee Yojana launched?Show answer
2015-16.
5.Which two states have the highest use of wells and tubewells in net irrigated area among those quoted?Show answer
Punjab (76.1 per cent) and Haryana (51.3 per cent).

Surface Water, Groundwater and Water Demand: frequently asked questions

What is the difference between available and utilisable water?

Available water is 1,869 cubic km from surface water and replenishable groundwater; utilisable water is the 60 per cent that can be put to beneficial uses, 1,122 cubic km.

Why is lagoon water used for irrigation of only some crops?

NCERT says lagoon and backwater water is generally brackish, yet it is used for fishing and for irrigating certain varieties of paddy crops and coconut. That its brackishness limits irrigation to such crops is our inference, not an NCERT sentence.

Which sector uses the most water in India?

Agriculture, at 89 per cent of surface water and 92 per cent of groundwater utilisation.

Are lagoons and backwaters in the 2026-27 syllabus?

Yes. The syllabus lists surface water and groundwater resources, lagoons and backwaters, and water demand and utilisation under Chapter 4.