Chapter 13 · 16 min read

Water Resources of India

India's water resources — surface water basins, groundwater crisis (world's largest user), 89 Ramsar wetlands, major lakes, glaciers, traditional harvesting systems, and Ken–Betwa interlinking project.

Overview

India is a water-rich country on average — receiving ~4,000 billion cubic metres (BCM) of precipitation annually. Yet it faces acute water stress because:

  • Rainfall is highly seasonal (75–80% in just 4 months of SW Monsoon).
  • Rainfall is spatially uneven (Meghalaya ~11,000 mm vs Jaisalmer ~100 mm).
  • Population density is among the world's highest in water-stressed basins.
  • Groundwater is being extracted far faster than it recharges.

India's Water Budget (Annual)

CategoryVolume
Total precipitation~4,000 BCM
Utilizable surface water~690 BCM
Replenishable groundwater~433 BCM
Total utilizable water~1,123 BCM
Current annual use (2024)~800–850 BCM
Irrigation share of use~80%
Domestic + industrial~20%

India has 4% of the world's freshwater resources but supports 18% of the world's population.


Surface Water Resources

River Basins

India has 12 major river basins (each >20,000 km²) and numerous minor basins. Surface water potential is concentrated in a few large basins:

River BasinBasin Area (km²)Annual Potential (BCM)
Ganga–Brahmaputra–Meghna11.0 lakh~525 (largest)
Godavari3.13 lakh~110
Krishna2.58 lakh~78
Indus (India's portion)3.21 lakh~73
Mahanadi1.41 lakh~66
Cauvery0.81 lakh~21
Narmada0.98 lakh~45

Key fact: The Ganga–Brahmaputra–Meghna system alone carries ~46% of India's total river flow.

Inter-State Water Disputes

Water sharing between states is a major source of conflict. Key disputes:

DisputeRiversStates InvolvedStatus (2024)
CauveryCauveryTamil Nadu vs KarnatakaCWDT award (2007); SC modified (2018); disputes continue
KrishnaKrishnaMaharashtra, Karnataka, AP, TelanganaBrijesh Kumar Tribunal-II ongoing
Mahadayi (Mandovi)MahadayiGoa vs Karnataka, MaharashtraTribunal award 2023: 13.42 TMC to Karnataka
Sutlej–Yamuna Link (SYL)Ravi-Beas watersPunjab vs HaryanaSC case; canal incomplete since 1990
VamsadharaVamsadharaAP vs OdishaTribunal constituted

Major Dams and Reservoirs

India has ~5,745 large dams — the third highest in the world (after China and USA).

DamRiverStateKey Feature
Tehri DamBhagirathi (Ganga)UttarakhandIndia's tallest dam (260.5 m); rock-and-earth fill
Bhakra-NangalSutlejHP/PunjabIndia's highest concrete gravity dam (226 m); Gobind Sagar reservoir
HirakudMahanadiOdishaWorld's longest earthen dam (25.8 km)
Nagarjuna SagarKrishnaTelangana/APOne of the world's largest masonry dams
Sardar SarovarNarmadaGujaratIndia's largest concrete gravity dam by volume; height 138.68 m
Indira SagarNarmadaMPIndia's largest reservoir by storage capacity (12.22 BCM)
KoynaKoynaMaharashtraLargest hydropower project in Maharashtra
Farakka BarrageGangaWest BengalDiverts Ganga water into Hooghly; Bangladesh disputes

Trap: Bhakra is India's highest concrete gravity dam; Tehri is India's tallest dam (a different category — rockfill/earthfill). Indira Sagar has the largest reservoir but Sardar Sarovar is the largest concrete gravity dam.


Groundwater Resources

Importance and Extent

  • India is the world's largest user of groundwater — extracting ~250 BCM/year (~25% of global groundwater extraction).
  • Groundwater irrigates ~65% of India's net irrigated area.
  • ~80% of rural drinking water comes from groundwater.
  • Total replenishable (dynamic) groundwater: ~433 BCM/year.

Groundwater Stress — CGWB 2024

CategoryDefinitionBlocks
Over-exploitedExtraction > 100% of recharge~1,114 blocks
Critical90–100% of recharge~314 blocks
Semi-critical70–90% of recharge~1,145 blocks
Safe<70% of recharge~3,863 blocks

Most over-exploited states: Punjab (~76% blocks over-exploited), Haryana, Rajasthan, Delhi, Tamil Nadu (Tamil Nadu's hard rock aquifers recharge slowly).

UPSC Mains 2024 (direct question): "Examine the causes of groundwater depletion in India. What measures have been taken to address this?"

Causes of Groundwater Depletion

  1. Free/highly subsidised electricity for irrigation pumps — farmers pump without cost signal; Punjab paddy cultivation requires 1,200–1,400 mm water but gets only 400–500 mm rain.
  2. Green Revolution emphasis on water-intensive crops — paddy in Punjab, sugarcane in Maharashtra — far exceed local water balance.
  3. Rapid urbanisation — impermeable surfaces reduce recharge; overextraction for cities.
  4. Weak regulation — no licensing for borewells in most states; anyone can drill.
  5. Climate change — erratic monsoon → farmers over-pump during dry spells.

Government Initiatives

SchemeKey Feature
Atal Bhujal Yojana (2020)₹6,000 cr scheme; community-led groundwater management in 7 states (Gujarat, Maharashtra, Rajasthan, UP, MP, Karnataka, Haryana)
Jal Shakti Abhiyan: Catch the RainRainwater harvesting; check dams; rejuvenation of traditional water bodies
PM Krishi Sinchai Yojana (PMKSY)"Har Khet Ko Pani, More Crop Per Drop"; micro-irrigation; convergence of water schemes
National Aquifer Mapping (NAQUIM)CGWB mapping aquifer systems; basis for regulation
Draft National Water Policy 2020Shift to basin-level management; pricing reform; groundwater regulation bill

Lakes of India

Types of Lakes

TypeFormationExamples
Glacial lakesGlacial scouring or moraine dammingDal, Wular (J&K), Gurudongmar (Sikkim)
Tectonic lakesFaulting and subsidenceWular (J&K), Loktak (Manipur)
Oxbow lakesRiver meander cut-offsKanwar Jheel (Bihar), Dal (Assam)
Lagoons (coastal)Sand bars blocking sea inletsChilika (Odisha), Pulicat (AP/TN), Vembanad (Kerala)
Crater lakesVolcanic cratersLonar (Maharashtra)
Saline lakes (playa)Inland drainage basinsSambhar (Rajasthan), Didwana
Man-made reservoirsDam constructionGobind Sagar, Indira Sagar

Major Lakes

LakeStateTypeKey Facts
Chilika LakeOdishaCoastal lagoonIndia's largest coastal lagoon; Asia's largest; ~1,100 km²; Ramsar site 1981; Irrawaddy dolphins
Wular LakeJ&KTectonic/glacialLargest freshwater lake in India; ~189 km² (seasonal variation: 24–260 km²); Ramsar site
Dal LakeJ&KGlacialFamous houseboat tourism; floating gardens (Rad); under environmental threat
Loktak LakeManipurTectonicLargest freshwater lake in NE India; famous for phumdis (floating biomass islands); Keibul Lamjao NP (only floating NP) floats on it
Vembanad LakeKeralaCoastal lagoonLongest lake in India (~96 km); Ramsar site; Kuttanad below sea level farming area
Sambhar LakeRajasthanSaline/playaLargest saline lake in India; Ramsar site 1990
Lonar LakeMaharashtraCrater lakeOnly saline soda crater lake in the world; 52,000 years old; Ramsar site 2020
Kolleru LakeAndhra PradeshFreshwaterBetween Krishna and Godavari deltas; Ramsar site
Bhoj WetlandMadhya PradeshMan-madeTwo lakes in Bhopal; Ramsar site 2002

Trap: "Chilika is the largest lake in India" → Chilika is the largest coastal lagoon; Wular is the largest freshwater lake. Different categories.


Wetlands and Ramsar Sites

What is a Ramsar Site?

The Ramsar Convention on Wetlands (1971, Ramsar, Iran) is an international treaty for conservation of wetlands. India signed it in 1982.

  • A Ramsar Site = wetland of international importance designated under the Convention.
  • India has 89 Ramsar Sites (as of April 2026) — largest number in Asia and among the top globally.
  • Total area: ~13.5 lakh hectares.

India's Ramsar expansion timeline:

  • 1981: 1 site (Chilika)
  • 2021: India added 14 new sites in one year (largest single-year addition)
  • 2022: 28 new sites added — another record
  • 2026: 89 total

Important Ramsar Sites (UPSC Frequently Asked)

Ramsar SiteStateKey Feature
Chilika LakeOdishaFirst Indian Ramsar site (1981); Asia's largest coastal lagoon
Keoladeo Ghana NPRajasthanBharatpur Bird Sanctuary; migratory waterfowl; UNESCO WHS
Wular LakeJ&KLargest freshwater lake in India
Loktak LakeManipurPhumdis (floating islands); Keibul Lamjao floating NP
Sambhar LakeRajasthanLargest saline lake; flamingos
Vembanad-KolKeralaKuttanad — farming below sea level; Nehru Trophy boat race
Kolleru LakeAndhra PradeshBetween Godavari–Krishna deltas
Harike WetlandPunjabConfluence of Beas and Sutlej; Indira Gandhi Canal headwork
Deepor BeelAssamLarge floodplain lake west of Guwahati; Ramsar site
Renuka WetlandHimachal PradeshSmallest Ramsar site in India
Lonar LakeMaharashtraSaline soda crater lake; Ramsar 2020
Sultanpur NPHaryanaBird sanctuary near Delhi
Thol LakeGujaratFlamingo habitat
Wadhvana WetlandGujaratMigratory birds from Central Asia

States with most Ramsar sites (2026): Tamil Nadu (16) > Uttar Pradesh (10) > Gujarat (6).

Montreux Record

The Montreux Record is a list of Ramsar sites where ecology has deteriorated due to human activity or natural change:

  • India's current Montreux Record sites: Keoladeo Ghana (Rajasthan), Loktak Lake (Manipur).
  • Chilika Lake was removed from Montreux Record in 2002 after successful ecological restoration.

Glaciers and Freshwater Stored as Ice

Himalayan Water Tower

The Himalayas contain the largest concentration of glaciers outside the polar regions — often called the "Third Pole" or "Water Tower of Asia".

FeatureValue
Number of Himalayan glaciers~9,575 (Geological Survey of India)
Total glaciated area (India)~37,000 km²
Freshwater stored~3,735 BCM (estimate)
Key rivers fed by glaciersIndus, Ganga (Bhagirathi, Alaknanda), Brahmaputra

Glacier retreat (IPCC AR6 + GSI data):

  • ~70% of Himalayan glaciers are retreating.
  • Gangotri glacier: retreating at ~22 m/year average (2000–2023).
  • Zemu glacier (Sikkim): retreat accelerating; contributed to 2023 GLOF.
  • Siachen glacier: some advance due to increased snowfall from WDs — but overall mass balance negative.
  • Impact on rivers: Short-term increase in river flow (glacial melt); long-term risk of reduced dry-season flows as glaciers shrink (called "peak water" followed by decline).

Trans-Himalayan River Sources

RiverGlacial Source
GangaGangotri glacier (Bhagirathi); Satopanth, Bhagirath Kharak (Alaknanda)
YamunaYamunotri glacier
IndusSengge Khabab spring (Tibet); Siachen glacier area
ChenabBara Lacha La area glaciers
Brahmaputra (Tsangpo)Angsi glacier (Tibet)

Water Conservation Methods — Traditional and Modern

Traditional Methods (UPSC Frequently Asked)

MethodRegionDescription
JohadRajasthanEarthen check dam impounding rainwater; community-managed
Kund / TankaRajasthanUnderground cylindrical cistern for household rainwater
KhadinJaisalmerAgricultural embankment to trap runoff for crops
Bawdi / BaoliRajasthan, GujaratOrnate stepwell; community water access
Karez / KarizLadakhUnderground horizontal tunnel (qanat) tapping subsurface water
Zabo / RuzaNagalandHilltop rainwater harvesting integrated with forest conservation
PhadMaharashtra (Nashik, Jalgaon)Community irrigation system using river diversions
Ahar-PyneBiharAhar = catchment reservoir; Pyne = channels feeding ahars
JackwellsGoaNatural springs tapped via stone-lined wells
VavGujaratOrnate stepwells (Rani ki Vav, Patan — UNESCO WHS)
SurangamKeralaHorizontal tunnel for groundwater extraction without a well
EriTamil NaduCommunity irrigation tank system
OoranisTamil NaduSmall drinking-water ponds
Bamboo Drip IrrigationMeghalayaTraditional drip irrigation using bamboo pipes (Khasi and Jaintia communities)

Meghalaya bamboo drip irrigation is listed by FAO as a Globally Important Agricultural Heritage System (GIAHS).

Modern Approaches

  • Micro-irrigation (drip and sprinkler): Covered under PMKSY; India has ~7.3 million ha under micro-irrigation (2024).
  • Aquifer recharge: Artificial recharge wells; check dams; percolation tanks.
  • Treated wastewater reuse: ~60% of India's wastewater is untreated; recycling is nascent.
  • Desalination: Small plants in Chennai, Lakshadweep; expensive for large-scale inland use.

Interlinking of Rivers (ILR)

National River Linking Project (NRLP)

Concept: Transfer water from surplus basins (peninsular rivers and Brahmaputra/Ganga with excess flow) to deficit basins (peninsular interior, Rajasthan, Gujarat).

ComponentLinksEstimated Cost
Himalayan Component14 links; Ganga–Brahmaputra–Meghna systemPart of ₹5.5 lakh cr total
Peninsular Component16 links; surplus south peninsular rivers to deficit areas
Total30 river links₹5.5–8.4 lakh cr (various estimates)

Ken–Betwa Link (first to be implemented):

  • Links Ken River (MP, surplus) to Betwa River (UP, deficit).
  • Approved: 2021; construction underway.
  • Daudhan Dam to be constructed; will submerge part of Panna Tiger Reserve — major controversy.
  • Estimated benefit: Irrigation to 8.11 lakh ha in Bundelkhand region.
  • Estimated cost: ~₹44,605 cr.

Arguments For ILR:

  • Solves water deficit in dry regions (Bundelkhand, Marathwada, Rajasthan).
  • Reduces flood damage in surplus basins.
  • Increases irrigated area and food security.

Arguments Against ILR:

  • Submergence of forests, farmland, wildlife habitat (Panna TR).
  • Disrupts river ecology, fish migration, downstream flow regimes.
  • Bangladesh and Nepal concerns about Himalayan component (diverting Ganga tributaries).
  • Climate change will alter surplus/deficit classifications — the premise may be wrong.
  • High cost, long gestation period.
  • Supreme Court (2012) directed fast-tracking; implementation still slow.

Water Scarcity and Stress

India's Water Stress Ranking

  • NITI Aayog Composite Water Management Index (CWMI) 2019: India is one of the world's worst water-stressed nations.
  • 21 Indian cities (including Delhi, Bengaluru, Chennai, Hyderabad) face "Day Zero" risk (near-total groundwater depletion) by 2030 — NITI Aayog report.
  • India's per capita water availability has fallen from ~5,177 m³/year (1951) to ~~1,450 m³/year (2021) — approaching "water stressed" threshold of 1,700 m³/year/person.

Day Zero Events in India

CityYearCrisis Type
Chennai2019Reservoirs hit zero; city nearly shut; tanker water for weeks
Shimla2018Severe shortage; tourist influx + dry winter
Bengaluru2024Worst water crisis in decades; 6,000+ tanker trips/day; groundwater depletion

Jal Jeevan Mission

  • Goal: Tap water connection (Functional Household Tap Connection — FHTC) to every rural household by 2024.
  • Progress (April 2026): ~78.9% of rural households have FHTC (15.31 cr of 19.39 cr households).
  • Previous baseline: Only 3.23 cr households (16.6%) had piped water in 2019.

UPSC Corner

High-Frequency Prelims Topics

  • India's Ramsar sites: 89 (as of 2026); largest in Asia. First site = Chilika (1981).
  • Largest coastal lagoon: Chilika (Odisha) | Largest freshwater lake: Wular (J&K).
  • Largest saline lake: Sambhar (Rajasthan) | Largest lake in NE India: Loktak (Manipur).
  • Montreux Record India: Keoladeo Ghana + Loktak (Chilika removed in 2002).
  • Lonar Lake: Only saline soda crater lake in the world; Maharashtra.
  • Phumdis: Floating biomass islands on Loktak Lake; Keibul Lamjao NP floats on them.
  • India = world's largest groundwater user: ~25% of global extraction.
  • Tehri Dam = tallest dam in India (260.5 m); Bhakra = highest concrete gravity dam.
  • Hirakud = world's longest earthen dam (25.8 km); Mahanadi, Odisha.
  • Bamboo drip irrigation (Meghalaya) = GIAHS (FAO recognized).
  • Harike Barrage = confluence of Beas + Sutlej; source of Indira Gandhi Canal.
  • Ken–Betwa link: First ILR project; Daudhan Dam; Panna Tiger Reserve controversy.

UPSC Mains GS1 Angles

  1. "India has abundant water resources yet faces acute water scarcity. Explain the paradox."
  2. "Examine the significance of Ramsar wetlands in India. Why have many been placed on the Montreux Record?"
  3. "Discuss the regional distribution of water resources in India and its implications for inter-state water disputes."
  4. "Traditional water harvesting systems of India are more appropriate than large dams. Critically examine."
  5. "Himalayan glaciers are the water towers of Asia. How is their rapid retreat threatening freshwater security?"

GS3 Angles

  1. "Critically examine the National River Linking Project — is it a solution to India's water crisis or an ecological disaster?"
  2. "Groundwater depletion is India's most serious long-term water challenge. Discuss causes and suggest policy responses." [UPSC Mains 2024]
  3. "Jal Jeevan Mission aims to provide tap water to every rural household by 2024. Evaluate its progress and challenges."

MCQ Trap Awareness

  • Trap: "Wular is a glacial lake" → Wular is tectonic in origin (though glacial processes contributed); officially classified tectonic.
  • Trap: "Chilika is the largest lake" → Chilika is the largest coastal lagoon; Wular = largest freshwater lake; separate categories.
  • Trap: "Loktak is in Assam" → Manipur (Deepor Beel is in Assam).
  • Trap: "Tehri Dam is on the Ganga" → Tehri is on the Bhagirathi (a source tributary); not the main Ganga stream.
  • Trap: "Ken–Betwa link will help Rajasthan" → Ken–Betwa helps Bundelkhand (MP and UP), not Rajasthan.
  • Trap: "Sardar Sarovar is India's tallest dam" → Tehri is India's tallest (260.5 m); Sardar Sarovar is the largest concrete gravity dam by volume.

Key Facts at a Glance

  • Total utilizable water: ~1,123 BCM/year
  • India = world's largest groundwater user (~250 BCM/year)
  • Ramsar Sites (2026): 89 — largest in Asia; first = Chilika (1981)
  • Largest coastal lagoon: Chilika, Odisha (~1,100 km²)
  • Largest freshwater lake: Wular, J&K (~24–260 km² seasonal)
  • Largest saline lake: Sambhar, Rajasthan (Ramsar 1990)
  • India's tallest dam: Tehri (260.5 m) — Bhagirathi, Uttarakhand
  • Longest earthen dam: Hirakud (25.8 km) — Mahanadi, Odisha
  • Largest reservoir by storage: Indira Sagar (12.22 BCM) — Narmada, MP
  • Montreux Record sites: Keoladeo Ghana (Rajasthan) + Loktak (Manipur)
  • Ken–Betwa Link: First ILR project; Bundelkhand; Daudhan Dam; Panna TR controversy
  • Per capita water availability (2021): ~1,450 m³/year (near "water stressed" threshold)
  • Jal Jeevan Mission coverage (April 2026): ~78.9% rural households
Key Facts(18 of 18)

Bhakra Dam on the Sutlej River (226 m) is India's highest concrete gravity dam; its reservoir is called Gobind Sagar. Sardar Sarovar on the Narmada (138.68 m) is the largest concrete gravity dam by volume.

India receives ~4,000 BCM of precipitation annually but has only ~1,123 BCM of utilizable water (690 BCM surface + 433 BCM groundwater). Irrigation accounts for ~80% of all water use.

India holds 4% of the world's freshwater resources but supports 18% of the world's population, making per-capita water availability critically low at ~1,450 m³/year (2021) — near the 'water stressed' threshold of 1,700 m³/year.

India is the world's largest user of groundwater, extracting ~250 BCM/year — about 25% of global groundwater extraction. Groundwater irrigates ~65% of India's net irrigated area and supplies ~80% of rural drinking water.

The CGWB 2024 assessment classifies ~1,114 blocks as 'over-exploited' (extraction >100% of recharge). Punjab has ~76% of its blocks over-exploited, making it the most groundwater-stressed major state in India.

India has ~5,745 large dams — the third highest in the world after China and USA. Tehri Dam (260.5 m, Bhagirathi River, Uttarakhand) is India's tallest dam; it is a rock-and-earth fill type, not a concrete gravity dam.

Hirakud Dam on the Mahanadi River (Odisha) is the world's longest earthen dam at 25.8 km. Indira Sagar Dam on the Narmada (MP) has India's largest reservoir by storage capacity at 12.22 BCM.

India has 89 Ramsar Sites (as of April 2026) — the largest number in Asia. Chilika Lake (Odisha) was India's first Ramsar site, designated in 1981. Tamil Nadu (16 sites) has the most Ramsar sites among Indian states.

Chilika Lake (Odisha, ~1,100 km²) is India's largest coastal lagoon and Asia's largest brackish water lagoon. Wular Lake (J&K) is India's largest freshwater lake, with a seasonal range of 24–260 km². Sambhar Lake (Rajasthan) is India's largest saline lake.

Loktak Lake (Manipur) is the largest freshwater lake in northeastern India, famous for 'phumdis' (floating biomass islands). Keibul Lamjao National Park, the world's only floating national park, floats on phumdis in Loktak Lake.

Lonar Lake (Maharashtra) is the only saline soda crater lake in the world, approximately 52,000 years old. It was designated a Ramsar site in 2020.

The Montreux Record lists Ramsar sites where ecology has deteriorated. India currently has two sites on the Montreux Record: Keoladeo Ghana (Rajasthan) and Loktak Lake (Manipur). Chilika Lake was successfully removed from the Record in 2002 after ecological restoration.

The Himalayas contain the largest concentration of glaciers outside the polar regions — called the 'Third Pole' or 'Water Tower of Asia'. India has ~9,575 Himalayan glaciers covering ~37,000 km², storing ~3,735 BCM of freshwater. About 70% are retreating.

The Atal Bhujal Yojana (2020) is a ₹6,000 crore scheme for community-led groundwater management in 7 states: Gujarat, Maharashtra, Rajasthan, UP, MP, Karnataka, and Haryana.

Bamboo drip irrigation practised by the Khasi and Jaintia communities of Meghalaya is recognized by the FAO as a Globally Important Agricultural Heritage System (GIAHS). It is a traditional method channelling spring water to terraced fields via bamboo pipes.

The Ken–Betwa River Link, India's first river interlinking project under the National River Linking Project, received Cabinet approval in December 2021. The Daudhan Dam on Ken River (MP) will submerge ~9,000 ha of Panna Tiger Reserve, at an estimated cost of ₹44,605 crore.

NITI Aayog's Composite Water Management Index (2019) warned that 21 Indian cities including Delhi, Bengaluru, Chennai, and Hyderabad face 'Day Zero' (near-total groundwater depletion) risk by 2030. Bengaluru faced its worst water crisis in decades in 2024.

Jal Jeevan Mission aims to provide Functional Household Tap Connections (FHTC) to every rural household. As of April 2026, ~78.9% of rural households (15.31 crore of 19.39 crore) have FHTC, up from just 16.6% in 2019.

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