Water Resources of India: Availability, Use and Conservation

1. India's water endowment: precipitation, surface water and lagoons

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• Water is a cyclic (renewed through the water cycle) and abiotic (non-living) resource. It covers about 71% of the earth's surface, but only about 3% of it is freshwater (Class 12).
• Water resources of India (NCERT, based on older CWC estimates): India has 2.45% of the world's area, 4% of its water and more than 17% of its people (now about 18%). Rain and snow bring about 4,000 cubic km a year. Surface water plus replenishable groundwater is 1,869 cubic km. Only about 60% of this, or 1,122 cubic km, can be used: 690 cubic km of surface water and 432 of groundwater. CWC's 2019 reassessment puts average yearly availability at about 1,999 cubic km (verify current).
• Surface water resources are rivers, lakes, ponds and tanks. About 10,360 rivers longer than 1.6 km carry about 1,869 cubic km a year. Only about 690 cubic km (32%) can be used, because of relief and because most rain falls in the monsoon months.
• The Ganga, Brahmaputra and Barak basins cover about one-third of India's area but hold 60% of its surface water. The Godavari, Krishna and Kaveri are already heavily tapped. The Ganga and Brahmaputra are not.
• Lagoons and backwaters form along cut-up (indented) coasts: Vembanad and Ashtamudi in Kerala, Chilika in Odisha, the lagoons of West Bengal, and Pulicat on the Andhra Pradesh-Tamil Nadu border. Their water is brackish (slightly salty) but is used for fishing and for growing some paddy varieties and coconut.
• Census of water bodies (first edition, Jal Shakti Ministry, 2023): it counted about 24.2 lakh ponds, tanks, lakes and reservoirs. Most are rural ponds, West Bengal has the most, and some are encroached on or no longer used (verify current).

2. Groundwater: the resource and how it is assessed

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• Groundwater is water stored underground in soil pores and in rock layers called aquifers. Rain, rivers, canals and tanks recharge (refill) it. NCERT puts India's replenishable groundwater at about 432 cubic km. India is the world's largest user: groundwater supplies over 60% of irrigation and about 85% of rural drinking water (verify current).
• Use by state (Class 12):

Level of use	States
Very high	Punjab, Haryana, Rajasthan, Tamil Nadu (highest in the south)
Moderate	Gujarat, Uttar Pradesh, Bihar, Tripura, Maharashtra
Low	Chhattisgarh, Odisha, Kerala

• Aquifer geography: the Indo-Gangetic-Brahmaputra plains have thick, productive alluvial aquifers. About two-thirds of India sits on hard rock (basalt, granite-gneiss) that holds little water and runs dry fast under pumping (Deccan, Karnataka, Telangana).
• Dynamic Ground Water Resource Assessment: the CGWB and the states assess every block each year. Stage of extraction = yearly extraction ÷ yearly extractable recharge × 100. In 2024 the national stage was about 60% (verify current).
• Over-exploited groundwater block: a unit where the stage is above 100%. The four classes are safe (up to 70%), semi-critical (70-90%), critical (90-100%) and over-exploited (above 100%). Over-exploited units cluster in Punjab, Haryana, Rajasthan and Delhi.
• National Aquifer Mapping and Management Programme (NAQUIM; CGWB, from 2012): it maps the extent, yield and quality of aquifers at 1:50,000 scale over about 25 lakh sq km, so that management plans can be drawn up with the states.
• Law: a landowner may still pump freely, because groundwater rights go with land ownership. The Model Groundwater Bills (2005, 2011, 2016) propose treating it as a public trust (a shared resource the state holds for everyone) (verify current).

3. Water scarcity: causes and measures

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• Water scarcity means usable water is short of what people need. Class 10 says it is caused less by low rainfall than by over-exploitation, excessive use and unequal access among social groups.
• Main causes:
• A large, growing population needs water at home and to grow food.
• Dry-season irrigation from private wells and tubewells uses the most water.
• Industry uses a lot of water and also needs hydropower.

• In cities, housing societies pump their own groundwater.

• Scarcity can also be about quality. Water may be plentiful but unusable because it is polluted. So a high-rainfall region can still be water-scarce if it has a large population or dirty water (Class 10 exercise).

• Per capita water availability (water per person per year) falls as population grows. CWC and MoJS figures: about 5,177 cubic metres in 1951, 1,816 in 2001, 1,545 in 2011 and about 1,486 in 2021, with about 1,367 projected for 2031 (verify current).
• Falkenmark indicator (Malin Falkenmark, 1989): below 1,700 cubic metres per person a year is water stress, below 1,000 is scarcity and below 500 is absolute scarcity. India as a whole is water-stressed. The Sabarmati, Pennar, Cauvery and the Kutch-Saurashtra rivers are already scarce.
• Day Zero is the day a city's taps run dry because its reservoirs fall below usable levels. Cape Town just avoided it in 2018. Chennai's main reservoirs dried up in June 2019. Bengaluru's borewells failed in 2024.

4. Water demand: sectoral use, irrigation need and efficient irrigation

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• Sectoral water use (Class 12):

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

Industrial and domestic shares will grow as the economy develops. NCIWRD (1999) projected demand of about 1,180 cubic km by 2050, close to the usable total (verify current).

• Need for irrigation in India: rainfall varies by place and season; the north-west and the Deccan are drought-prone; winters and summers are dry; monsoon breaks hit even West Bengal and Bihar; and rice, sugarcane and jute need a lot of water. Irrigation allows several crops a year and makes HYVs (high-yielding varieties) work.
• Over 85% of net sown area is irrigated in Punjab, Haryana and western Uttar Pradesh. Wells and tubewells water 76.1% of Punjab's and 51.3% of Haryana's net irrigated area.
• Pradhan Mantri Krishi Sinchayee Yojana (PMKSY, 2015-16) aims to give every farm some protective irrigation. Its parts are the Accelerated Irrigation Benefit Programme, Har Khet Ko Pani (water to every field), Per Drop More Crop (efficient use) and a watershed component for rain-fed areas.
• Micro-irrigation (drip and sprinkler) brings water close to the roots and saves about 30-50% of water. Maharashtra, Karnataka and Andhra Pradesh lead (verify current).
• Drip irrigation: pipes and emitters drip water onto the roots. It saves 40-70% of water and fertiliser and suits orchards, sugarcane and cotton.

• Sprinkler irrigation: pressurised nozzles spray water like rain. It suits uneven land and sandy soils (Rajasthan, Haryana).

• Virtual water (Tony Allan, 1993) is the water used to make a product, so trade moves water. When India exports rice, it is in effect exporting groundwater from stressed Punjab and Haryana.

5. Groundwater depletion and contamination

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• Groundwater depletion: when more water is pumped out than is recharged, the water table falls, pumping costs rise and wells fail. Heavy tubewell use in Punjab, Haryana and western Uttar Pradesh has caused it, and intensive irrigation is making the soil saltier (Class 12).
• Punjab groundwater crisis (Class 8):
• HYV wheat and paddy from the 1960s needed more water.
• Free electricity for farms led to over-pumping.
• Pesticides and fertilisers seeped into the aquifers.

• About 80% of Punjab is classed overexploited. Across a large part of the state, water lies deeper than about 30 m (June 2022 map). The 2024 assessment put Punjab's stage of extraction at about 156%, with about three-quarters of its blocks over-exploited (verify current).

• Arsenic contamination: the arsenic is natural (geogenic). It is released from young alluvial sediments in West Bengal, Bihar, Uttar Pradesh and Assam, and heavy pumping makes it worse. Long exposure causes skin lesions and cancer. The Jal Kranti Abhiyan proposed arsenic-free wells.

• Fluoride contamination: it comes from fluoride-bearing hard rocks in dry areas. Over-withdrawal worsens it in Rajasthan and Maharashtra, and it also affects Telangana's Nalgonda, Andhra Pradesh, Gujarat and Karnataka. It causes dental and skeletal fluorosis (damage to teeth and bones). Recharging aquifers with rainwater dilutes it.
• Groundwater contamination belts: arsenic in the Ganga-Brahmaputra plains, fluoride in the dry hard-rock belt, uranium in parts of Punjab's Malwa, and seawater seeping into coastal aquifers in Saurashtra and Tamil Nadu (verify current).

6. Hydraulic heritage and traditional water harvesting

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• Ancient hydraulic structures of India (Class 10, citing CSE's Dying Wisdom, 1997): Sringaverapura near Prayagraj channelled Ganga floodwater (1st century BCE). The Mauryan period saw many dams and irrigation works. Other old works stood at Kalinga, Nagarjunakonda, Bennur and Kolhapur. Bhopal Lake dates from the 11th century, and Alauddin Khalji built the Hauz Khas tank in Delhi (13th-14th century).
• Kallanai (Grand Anicut) is a stone dam across the Kaveri near Thanjavur, built by Karikala Chola about 1,800 years ago. It still irrigates the delta and is one of the world's oldest working diversion structures.
• Traditional water harvesting systems were each designed for local rainfall and soil:

System	Region	How it works
Guls and kuls	Western Himalayas	Channels divert glacier and stream water; in Spiti a kul feeds a village tank (Kaza)
Inundation channels	Bengal floodplains	Carry floodwater and fertile silt to fields
Khadin	Jaisalmer (Paliwal Brahmins)	An earthen bank across a slope holds runoff so the soil stays moist for a crop
Johad	Rajasthan (Alwar)	Crescent-shaped earthen check dam or dug-out pond
Taanka	Bikaner, Phalodi, Barmer	Underground house tank fed from the roof; the first rain is let go; stored palar pani lasts till the next rains
Kund	Thar	Saucer-shaped catchment draining into a covered underground pit in open ground
Ahar-pyne	South Bihar	Pynes (channels) divert river water into ahars (embanked basins) for paddy
Eri	Tamil Nadu	Chained tanks that irrigate, recharge groundwater and control floods
Phad system	Tapi basin, north Maharashtra	Bandharas (weirs) and canals feed blocks of fields (phads), each growing one crop
Bamboo drip irrigation	Meghalaya (about 200 years old)	Bamboo pipes carry 18-20 litres of water down to 20-80 drops a minute at betel-leaf and pepper plants

• Decline: taankas fell out of use once the Indira Gandhi Canal brought water to western Rajasthan, though some homes keep them because they prefer the taste.

7. Multipurpose river projects: the "temples of modern India"

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• A dam is a barrier across flowing water that blocks, directs or slows it, usually creating a reservoir. Water passes over a spillway or weir. Dams are classed by structure (timber, embankment, masonry) and by height.
• A multipurpose river project combines irrigation, hydropower, water supply, flood control, navigation, recreation and fish breeding. These projects got high priority in the Five Year Plans.
• Temples of modern India: Nehru's name for big dams. He believed they would link farming and village life with industry and city growth, and help India leave its colonial past behind.
• Bhakra-Nangal project (Satluj): the Bhakra dam at Bilaspur, Himachal Pradesh (completed 1963) forms the Gobind Sagar. With the Nangal dam in Punjab, it supplies power and canal water to Punjab, Haryana and Rajasthan.
• Hirakud dam (Mahanadi, near Sambalpur, Odisha; inaugurated 1957) is among the world's longest earthen dams and combines water storage with flood control.
• Damodar Valley Corporation (7 July 1948) was India's first multipurpose river valley authority, modelled on the USA's Tennessee Valley Authority. It was set up to tame the Damodar, the "river of sorrow", through dams at Tilaiya and Maithon (Barakar), Panchet (Damodar) and Konar.
• Sardar Sarovar project (Narmada, Kevadia, Gujarat; completed 2017; 138.68 m high) serves Gujarat, Rajasthan, Madhya Pradesh and Maharashtra. It irrigates 18.45 lakh ha in 15 Gujarat districts and 2.46 lakh ha in Barmer and Jalore.
• Kaleshwaram lift irrigation project (Godavari, Telangana; 2019) is one of the world's largest multi-stage lift schemes, pumping water uphill. Piers of its Medigadda barrage sank in October 2023, which raised safety and cost concerns (verify current).

8. The large-dam debate and dam safety

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• Criticism of large dams (Class 10):
• Dams change a river's natural flow. Silt piles up in the reservoir, the river bed below turns rocky and floodplains lose fertile silt.
• Dams break rivers into pieces, so fish cannot swim upstream to breed. Reservoirs drown forests and soil.
• A reservoir full of silt holds less flood water, so dams can fail to stop floods. Reservoirs can also trigger earthquakes (Koyna, 1967) and spread water-borne diseases.

• Irrigation pushes farmers towards thirsty cash crops, which makes soil salty. Dams also displace people and destroy livelihoods.

• Movements: the Narmada Bachao Andolan (Medha Patkar, Baba Amte) fought displacement at Sardar Sarovar. In 2000 the Supreme Court allowed construction on condition that people were resettled. Tehri on the Bhagirathi, India's highest dam (about 260 m) and in a seismic zone, was opposed by Sunderlal Bahuguna.

• Dam Safety Act 2021 requires regular checks, emergency plans and upkeep of specified dams. It set up a National Committee on Dam Safety (policy) and a National Dam Safety Authority (regulator). India has about 5,700 large dams, third after China and the USA, and many are over 50 years old (verify current).
• Periyar Diversion Scheme (1895): water from the west-flowing Periyar is sent east through a tunnel into the Vaigai basin to irrigate the Madurai region of Tamil Nadu.
• Mullaperiyar dam is the 1895 masonry dam in Idukki, Kerala, behind that scheme. It is leased to Tamil Nadu (lease of 1886, 999 years), which runs it. Kerala points to its age and earthquake risk. In 2014 the Supreme Court allowed the water level to be raised to 142 ft.

9. Inter-state river disputes and river linking

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• Inter-state river water disputes: falling water supply breeds conflict between states. In Class 10's example, Karnataka and Andhra Pradesh objected when Maharashtra planned to divert more water at Koyna.
• Framework (details in polity): Article 262 lets Parliament set up a system to settle these disputes and keep courts out of them. Tribunals are formed under the Inter-State River Water Disputes Act 1956 (amended 2002 to add time limits). Examples: Krishna, Godavari, Narmada (1979), Ravi-Beas (1987; the SYL canal stalemate) and Mahadayi. Common problems are long delays, states ignoring awards, and politics.
• Kaveri water dispute (Karnataka, Tamil Nadu, Kerala, Puducherry; Class 8 shows the Mettur dam): the tribunal gave its award in 2007. The Supreme Court ruling of 16 February 2018 fixed normal-year shares at Karnataka 284.75 tmcft, Tamil Nadu 404.25, Kerala 30 and Puducherry 7, and set up the Cauvery Water Management Authority.
• Mahadayi water dispute (Goa, Karnataka, Maharashtra): the August 2018 tribunal award partly allowed Karnataka's Kalasa-Banduri plan to divert water east to the Malaprabha basin. Goa opposes it.
• River linking: NCERT's examples of moving water between basins are the Periyar diversion, the Indira Gandhi Canal and the Beas-Satluj link. The National Perspective Plan (1980) and NWDA identify 30 links: 14 Himalayan and 16 peninsular.
• Ken-Betwa link project is the first link under the plan. It moves Ken water to the Betwa in Bundelkhand (MP and UP) through the Daudhan dam. Its foundation was laid on 25 December 2024, and it will submerge part of Panna Tiger Reserve.
• Polavaram project (Godavari, Andhra Pradesh; a national project) carries Godavari water to the Krishna through its right canal. Odisha, Chhattisgarh and Telangana object to the flooding of tribal land upstream (verify current).

10. Transboundary rivers: Indus, Ganga, Teesta and Brahmaputra

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• Indus Waters Treaty (Karachi, 19 September 1960; Nehru and Ayub Khan; brokered by the World Bank):
• India got the eastern rivers (Ravi, Beas, Satluj). Pakistan got the western rivers (Indus, Jhelum, Chenab).
• India may make limited use of the western rivers, such as run-of-river hydropower.

• India put the treaty in abeyance (on hold) on 23 April 2025 after the Pahalgam attack (verify current).

• Ganga Waters Treaty (12 December 1996, India-Bangladesh): it shares the Ganga's dry-season flow (January-May) at the Farakka barrage (1975), measured in 10-day blocks. It runs for 30 years and expires in December 2026 (verify current).

• Teesta water dispute: the Teesta rises in Sikkim and flows through West Bengal into Bangladesh. West Bengal's objection blocked a 2011 interim deal. China has offered Bangladesh a Teesta project (verify current).
• Medog hydropower project: China began this project of about 60 GW on the lower Yarlung Tsangpo near the Great Bend in Tibet, close to Arunachal Pradesh, in July 2025. India fears changes to the Brahmaputra's flow, sediment and flood timing. In response it plans the Siang Upper Multipurpose Project, which local Adi communities oppose (verify current).
• Big picture: India is upstream of Pakistan and Bangladesh but downstream of China. This shapes its stand on how shared rivers should be governed (diplomacy in india-neighbours).

11. Rainwater harvesting and watershed management

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• Rainwater harvesting means catching and storing rain for use, or guiding it into pits, wells and borewells to recharge groundwater. It is cheap and eco-friendly. It raises water tables, dilutes fluoride and nitrates, reduces erosion and flooding, stops seawater seeping into coastal aquifers and saves pumping energy (Class 12).
• Rooftop rainwater harvesting: roof rain flows through pipes and a sand-brick filter into a sump, and the extra water recharges wells. In Gendathur (Mysuru), about 200 homes collect about 50,000 litres each a year from 1,000 mm of rain (Class 10).
• Shillong rooftop rainwater harvesting: Cherrapunji and Mawsynram, about 55 km away, get the world's highest rainfall, yet Shillong is short of water. Nearly every home harvests roof rain for 15-25% of its needs.
• Tamil Nadu rainwater harvesting mandate: Tamil Nadu was the first state to make rooftop harvesting compulsory for all buildings (2001-03), with penalties for defaulters.
• Watershed management means conserving surface water and groundwater by stopping runoff and recharging aquifers. In the broad sense, it means caring for all land, water, plants, animals and people in a watershed. It works only with community participation.
• Check dam: a small barrier across a stream that slows water, traps silt and recharges groundwater.

• Percolation tank: a pond that holds runoff so it seeps down and refills wells.

• Haryali (2003) is a central watershed project run by gram panchayats. It helps villagers conserve water for drinking, irrigation, fisheries and afforestation. Neeru-Meeru ("Water and You") is Andhra Pradesh's programme.

• Ralegan Siddhi (Ahmednagar, Maharashtra): from 1975, Anna Hazare led villagers in voluntary labour. They repaired a percolation tank, which refilled seven wells, and banned open grazing, tree felling, liquor and sugarcane.
• Arvary Pani Sansad (Alwar, Rajasthan): johads built with Tarun Bharat Sangh revived the Arvari river. In 1999 the villages formed this "water parliament" to make rules on water use.

12. Conservation, policy and the water missions

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• Water conservation and management (Class 12): water-saving technology, pollution control, watershed development, rainwater harvesting, recycling, conjunctive use (using surface water and groundwater together), linking basins and, above all, pricing water. CPCB checks water quality at 507 stations, and the Yamuna between Delhi and Etawah is the most polluted stretch.
• Recycling and reuse of water: treated wastewater can cool industries and fight fires, and bath or kitchen water can water gardens. This saves clean water for drinking.
• Desalination removes salt from seawater, mostly by reverse osmosis. Chennai's Minjur and Nemmeli plants are India's largest, but the process uses a lot of energy and leaves salty brine behind.
• National Water Policy 2012 (earlier policies 1987 and 2002) calls for:
• a national water framework law;
• treating water as an economic good once drinking water, sanitation, food security and ecosystem needs are met;
• climate adaptation, water footprints and water audits;

• smaller gaps between urban and rural supply norms, and community participation. The Ministry of Jal Shakti was formed in May 2019.

• Jal Kranti Abhiyan (2015-16) proposed a 'Jal Gram' (a water-stressed model village) in each of 672 districts, model command areas of about 1,000 ha, arsenic-free wells and mass awareness.

• Jal Jeevan Mission (15 August 2019) aims to give every rural home a working tap supplying 55 litres per person per day. Its deadline was extended to 2028 (verify current).
• Atal Bhujal Yojana (December 2019) runs in 8,220 gram panchayats in 80 districts of 7 states: Gujarat, Haryana, Karnataka, MP, Maharashtra, Rajasthan and UP. It seeks a shift "from consumption to conservation".
• Jal Shakti Abhiyan: Catch the Rain (2019, and every year since 2021): "Catch the Rain, where it falls, when it falls".
• Mission Amrit Sarovar (April 2022): at least 75 ponds of about one acre in each district.

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Exam angles

Prelims — high-yield facts and traps

• NCERT numbers: India has 4% of the world's water and over 17% of its people. Precipitation is 4,000 cubic km a year; 1,869 cubic km is available and 1,122 is usable (690 surface + 432 groundwater). The Ganga-Brahmaputra-Barak basins hold 60% of surface water on about one-third of the area.
• Agriculture uses 89% of surface water and 92% of groundwater. Wells and tubewells water 76.1% of Punjab's and 51.3% of Haryana's net irrigated area. Tamil Nadu is the south's highest groundwater user.
• Groundwater stages: safe up to 70%, semi-critical 70-90%, critical 90-100%, over-exploited above 100%. Falkenmark thresholds: 1,700 (stress), 1,000 (scarcity), 500 (absolute scarcity) cubic metres per person a year.
• Traditional systems and their regions: khadin (Jaisalmer), taanka (Bikaner, Phalodi, Barmer), kul (Spiti), ahar-pyne (south Bihar), eri (Tamil Nadu), phad (Tapi basin), bamboo drip (Meghalaya), Zabo (Nagaland), Kallanai (Kaveri).
• Dam, river and state: Bhakra (Satluj, HP), Hirakud (Mahanadi, Odisha), Sardar Sarovar (Narmada, Gujarat), Nagarjuna Sagar (Krishna), Tilaiya and Maithon (Barakar), Tehri (Bhagirathi), Kaleshwaram (Godavari, Telangana), Mullaperiyar (Periyar, in Kerala, run by Tamil Nadu).
• Indus 1960: the eastern rivers go to India. Ganga 1996: Farakka, expires December 2026. Teesta: no treaty.
• Schemes: Atal Bhujal covers 7 states; JJM targets 55 lpcd; Amrit Sarovar builds 75 ponds per district; gram panchayats run Haryali; the Dam Safety Act set up the NCDS and NDSA.
• Kaveri 2018 shares: Tamil Nadu 404.25 tmcft and Karnataka 284.75 tmcft. Ken-Betwa is the first river link. Tamil Nadu was the first state to mandate rooftop harvesting.
• Traps: "Water scarcity happens only in low-rainfall areas" is FALSE (Shillong, Chennai). "Arsenic in groundwater is mainly industrial" is FALSE (it is natural, from alluvium). "Dams always reduce floods" is FALSE (silting reduces their capacity). "Rooftop harvesting grew in western Rajasthan after the Indira Gandhi Canal" is FALSE (it declined).

Mains — GS-I and GS-III themes

1. "Water scarcity in India is more a problem of management than of availability." Discuss with examples.
2. Groundwater depletion in north-west India: causes (HYVs, free power, paddy), effects on food security, and remedies (pricing, power reform, crop diversification, Atal Bhujal).
3. Multipurpose projects: temples of modern India or tombs of rivers? Weigh their benefits against their ecological and social costs.
4. Inter-state water disputes: why do tribunals fail, and what reforms are needed?
5. India as both an upstream and a downstream state: what the Indus treaty's abeyance and China's Medog project mean.
6. Can traditional harvesting and community watershed management be scaled up? Use Ralegan Siddhi and Alwar.
7. Judge the Jal Jeevan Mission and Atal Bhujal Yojana on whether both the water source and the service will last.

Current-affairs hooks

• CGWB's yearly groundwater assessments and Punjab-Haryana extraction figures.
• Indus treaty abeyance and new Indian projects on the western rivers; Ganga treaty renewal in December 2026; Teesta talks.
• Medog construction, the Siang Upper project and Brahmaputra flood-data sharing.
• Kaveri sharing in distress years; Mahadayi diversion; Mullaperiyar safety; Polavaram height and submergence.
• Ken-Betwa and other links (Par-Tapi-Narmada, Parbati-Kalisindh-Chambal-ERCP).
• JJM coverage and functionality audits; Day Zero warnings in Bengaluru, Chennai and Delhi.
• NDSA reports on dam incidents; reservoir levels in heatwave and drought years.