Water as a weapon: From Farakka to the Himalayas, South Asia’s new geopolitical tool

The Padma River once defined life in large parts of Bangladesh. Elderly residents in Rajshahi still remember a river so vast that villages measured seasons by its moods. Fishermen read its currents like maps, farmers waited for its floods to renew their soil, and boats stitched together commerce across the delta. 

But now, during the dry season, large stretches of that same river resemble broken sandbanks. The transformation has become more than an environmental crisis; in Bangladesh's political imagination, it is evidence of how water can be turned into a weapon.

That anxiety has intensified as the 30-year Indo-Bangladesh Ganges Water Sharing Treaty expires in December 2026. Signed in 1996, the treaty established a formula for sharing dry-season flows of the Ganges at the Farakka Barrage in India's West Bengal before the river enters Bangladesh as the Padma. But the agreement never fully resolved the deeper issue: Bangladesh, as the lower riparian state, remains dependent on upstream decisions taken by India.

The story of Farakka began long before Bangladesh was born. In the 1950s, India feared that the Kolkata port was dying under layers of silt as the Hooghly River lost the force required to flush sediment into the Bay of Bengal. 

The solution proposed by Indian planners was enormous: a barrage across the Ganges at Farakka, roughly 16.5 kilometres from what was then East Pakistan. The barrage would divert massive quantities of water through a 40-kilometre feeder canal into the Hooghly to save Kolkata port.

Construction began in 1961 despite objections from Pakistan, which warned of devastating downstream consequences. India completed the barrage in 1971 and formally commissioned it in 1975. 

That same year, Prime Minister Indira Gandhi and Bangladeshi leader Sheikh Mujibur Rahman signed a temporary 41-day agreement for a test run of the feeder canal. After Sheikh Mujib's assassination later that year, India continued withdrawing water unilaterally, triggering a diplomatic crisis that still shapes regional politics.

For Bangladesh, Farakka became synonymous with ecological decline. Reduced dry-season flow in the Padma devastated agriculture in the country's north-western districts, accelerated salinity intrusion from the Bay of Bengal, weakened river navigation, and damaged fisheries. The Sundarbans, the world's largest mangrove forest, also began experiencing increased salinity stress.

Researchers Md Abdul Kawser and Abu Md Shamsuddoha Samad, in their study titled "Political history of Farakka Barrage and its effects on environment in Bangladesh", noted that the ecological and environmental destruction created by Farakka has led to an irreparable loss of agriculture, fishing, forestry and ecosystem of Bangladesh. 

Their research estimated Bangladesh's economic losses between 1976 and 1993 at Tk113,240 million, nearly $3 billion, excluding flood and riverbank erosion damage.

The political dimensions of the dispute are equally important. Kawser and Samad argued that the emergence of post-colonial nation-states "developed a sense of individual ownership instead of collective ownership over the common rivers". 

Bangladesh and India share 54 transboundary rivers, yet the Ganges remains the only river governed by a formal treaty. The Teesta River agreement, negotiated in principle in 2011, still remains stalled because of opposition from India's West Bengal state government. 

The Farakka dispute repeatedly exposed how water diplomacy in South Asia is inseparable from domestic politics. During the 1970s, Bangladeshi leader Maulana Abdul Hamid Khan Bhasani mobilised mass protests against India's water diversion. Threatening a "Long March" towards Farakka in 1976, Bhashani warned of "devastating desertification" in Bangladesh. 

In a letter to Indira Gandhi, he appealed to her to "personally intervene and work out a solution yourself". If not, he warned, "I shall be compelled to follow the path of struggle I have learnt from your forefathers and Mahatma Gandhi."

India defended its actions by arguing that Farakka was essential for the Kolkata port. Indira Gandhi responded sharply that "India was open to persuasion and reasoned argument, but no one should expect India to submit to threats and palpably unreasonable and unjustified demands."

The tensions never truly disappeared. Between 1988 and 1996, there was no agreement in place at all, and India continued unilateral withdrawals during dry seasons. The eventual 1996 treaty established water-sharing formulas based on 10-day cycles between January and May. 

During the dry season, we are getting less water. The river flow is decreasing, and many problems are being created. Areas around the river are gradually drying up… The barrage will help ensure water supply for farmers and people across the country.

Tarique Rahman, Prime Minister, Bangladesh

Under the arrangement, India could divert up to 40,000 cusecs when the incoming flow exceeded 75,000 cusecs. If the flow dropped below 50,000 cusecs, both sides were required to enter emergency consultations.

Yet even after the treaty, actual flows remained lower than anticipated. Researchers observed that "almost every problem in the country associated with water has been attributed to the impact of Farakka".

Now Bangladesh is responding with engineering of its own. In May 2026, Dhaka approved the first phase of the Tk34,497 crore Padma Barrage project. Officials explicitly described it as a response to Farakka. Water Resources Minister Shahiduddin Chowdhury Anee stated that one objective was to negate the negative impact of the Farakka Barrage.

The project aims to store monsoon water and release it during dry seasons to combat salinity, revive dying distributary rivers, and support irrigation. Prime Minister Tarique Rahman recently defended the initiative by saying, "During the dry season, we are getting less water. The river flow is decreasing, and many problems are being created. Areas around the river are gradually drying up."

Rahman also linked reduced river flow to ecological degradation in the south. "The barrage will help ensure water supply for farmers and people across the country," he said, while warning that salinity intrusion was damaging the Sundarbans and surrounding ecosystems.

Md Zakir Hossain Khan, associate professor at Bangladesh Army University of Engineering & Technology, described Farakka as "a curse for North Bengal". He also warned against unilateral upstream control. 

Referring to international water law, he noted, "International law generally prohibits a country from unilaterally stopping or significantly altering the flow of a transboundary river." The principle, embedded in the 1997 United Nations Convention on the Law of the Non-Navigational Uses of International Watercourses, requires equitable and reasonable use of shared rivers.

The fear of water weaponisation is no longer limited to Bangladesh. In recent years, India and Pakistan have openly invoked water as a strategic instrument.

Following militant attacks in Indian-administered Kashmir in April 2025, India suspended participation in the 1960 Indus Waters Treaty. Prime Minister Narendra Modi declared, "India's water will flow for India's benefit, it will be conserved for India's benefit, and it will be used for India's progress."

Pakistan reacted furiously, warning that any attempt to stop water flow would be treated as an "Act of War". The Indus basin supports nearly a quarter of Pakistan's economy and irrigates much of its agricultural sector. 

Although there are arguments that India currently lacks sufficient infrastructure to fully block western river flows, New Delhi has already demonstrated partial leverage. In May 2025, India reportedly reduced downstream flow through the Chenab River by up to 90% after lowering sluice gates at the Baglihar dam.

But even limited manipulation during dry seasons could destabilise Pakistan's agriculture and electricity generation. India could also withhold hydrological data during monsoon periods, raising flood risks downstream.

But the broader geopolitical concern increasingly points northwards, towards China.

China's planned mega dam on the Yarlung Tsangpo River in Tibet represents perhaps the most ambitious hydro-strategic project in modern Asia. Located near the Indian border, the project is expected to generate up to 60 gigawatts of electricity, nearly three times the capacity of the Three Gorges Dam.

Officially, Beijing presents the dam as part of its green energy transition and regional development strategy. Chinese authorities argue that the project will help achieve carbon neutrality goals, improve water management, and integrate Tibet economically.

Downstream countries see something else entirely.

The Yarlung Tsangpo becomes the Brahmaputra in India and the Jamuna in Bangladesh, sustaining hundreds of millions of people across both countries. Chinese control over Tibet's rivers has therefore become a major geopolitical concern.

Beijing could manipulate river flow during political crises. Arunachal Pradesh Chief Minister Pema Khandu warned that the dam poses "a serious threat to our tribal livelihoods". Bangladesh worries that Chinese dams could trap nutrient-rich sediment essential to sustaining the Bengal delta.

Chinese cascade dams on the Mekong have reportedly reduced downstream flows by up to 70% during critical periods. Similar interventions on the Brahmaputra could transform water into a strategic lever over India and Bangladesh.

Chinese officials insist the project will not harm downstream countries, but Beijing has not published comprehensive environmental assessments or entered binding water-sharing agreements. China also remains outside the 1997 UN Watercourses Convention.

The implications are profound. South Asia's rivers increasingly resemble geopolitical fault lines where engineering projects, climate pressures, nationalism, and strategic rivalry converge.

The irony is that every country involved sees itself simultaneously as victim and defender. Bangladesh accuses India of creating artificial drought through Farakka. India accuses Pakistan of exploiting terrorism while warning of its own water vulnerabilities against China. 

Pakistan describes India's suspension of the Indus treaty as coercive warfare. China frames its dams as sovereign development projects while downstream neighbours interpret them as hydro-hegemonic tools.

Water, once viewed primarily as a shared natural resource, is steadily being reframed as an instrument of statecraft.