South Asia’s Riverine Landscape: Challenges and Opportunities

Few regions on Earth depend on rivers as completely as South Asia. The Himalayas feed a vast network of waterways that nourish farmland, power cities, and sustain nearly two billion people across multiple countries. Yet these same rivers rarely respect political borders. The Indus, the Ganga, and the Brahmaputra all begin in one country and flow through several others before reaching the sea. This simple geographic fact creates a web of dependence, cooperation, and tension that shapes the politics of the entire region. Understanding South Asia’s riverine landscape means understanding how water can be both a shared blessing and a source of conflict.

What makes South Asia a riverine neighbourhood 🔗

South Asia is usually understood to include eight countries: Afghanistan, Pakistan, India, Bangladesh, Nepal, Bhutan, Sri Lanka, and the Maldives. Together they form a distinct geopolitical region with the largest population in the world, much of it concentrated along river plains. The defining feature of this neighbourhood is that its great rivers are transboundary, meaning they cross one or more international borders during their journey.

Most of these rivers originate in the high Himalayan ranges and the Tibetan Plateau. They are fed by a combination of glacial melt, snowmelt, and monsoon rainfall, which gives them their perennial character. Because the mountains sit at the top of the system and the densely farmed plains lie below, the countries upstream hold a natural advantage over those downstream. This relationship between upper riparian states (those closer to the source) and lower riparian states (those further down) lies at the heart of nearly every water dispute in the region.

The three great river systems 🔗

South Asia’s water story revolves around two major international river systems. The Indus basin is shared by Afghanistan, China, India, and Pakistan, while the Ganges-Brahmaputra system is shared by Bangladesh, Bhutan, China, India, and Nepal.

The Indus originates near Lake Manasarovar on the Tibetan Plateau, flows through the Ladakh region of India, and then becomes the lifeline of Pakistan before emptying into the Arabian Sea. The Ganga rises in the Himalayas, flows across the north Indian plains, runs briefly along the India-Nepal border, and finally enters Bangladesh. The Brahmaputra has the most complicated path of all. It originates in Tibet as the Yarlung Tsangpo, enters India through Arunachal Pradesh, and flows into Bangladesh, where it is known as the Jamuna.

Why these rivers matter so much 🔗

The rivers of South Asia are not just geographic features. They are the foundation of food security, energy, and daily survival for hundreds of millions of people. Agriculture across the Indo-Gangetic plain depends almost entirely on river water for irrigation. Cities draw their drinking water from these flows. Hydroelectric projects in the mountains generate power for growing economies.

The dependence is especially stark for downstream nations. Bangladesh offers the clearest example. Nearly 60 percent of its agricultural economy depends on a consistent water supply from India. When too little water arrives, farmers face drought; when too much is released, fields and homes are flooded. This vulnerability explains why water-sharing is treated as a matter of national survival rather than mere resource management.

These rivers also carry deep cultural and spiritual meaning. They have shaped civilisations, defined borders, and been worshipped by people of many faiths for centuries. This blend of economic necessity and cultural reverence raises the stakes of any disagreement over how the water is divided.

How shared rivers become political flashpoints 🔗

The core difficulty is that there is no single regional body managing these waters. No regional organisation oversees these resources; instead, water is shared through a patchwork of bilateral agreements. This means each pair of neighbours negotiates separately, often leaving out other countries that share the same basin. The result is a fragmented system that struggles to address the river as a whole.

The Indus Waters Treaty 🔗

The most famous of these agreements is the Indus Waters Treaty. Signed on 19 September 1960 and brokered by the World Bank, it assigned the western rivers (Indus, Jhelum, and Chenab) to Pakistan and the eastern rivers (Ravi, Beas, and Sutlej) to India. For more than six decades, this treaty was celebrated as one of the world’s most resilient water agreements, surviving multiple wars and prolonged hostility between the two nations.

That stability was shaken in 2025. Following a deadly terror attack on civilians in Kashmir in April 2025, India announced that it would hold the treaty in abeyance, marking the first time tensions had disrupted the agreement. India has stated that the suspension will continue until Pakistan takes verifiable action against cross-border terrorism, while Pakistan has rejected the move. India has reiterated that the treaty will remain in abeyance and has pointed to its earlier attempt to discuss treaty modifications in light of changing technology and environment, which it says Pakistan rejected. The episode shows how even the most durable water arrangements can become hostage to wider security disputes.

The Ganges Water Treaty and the Farakka question 🔗

The other landmark agreement is the Ganges Water Sharing Treaty between India and Bangladesh. The dispute it sought to resolve dates back to the Farakka Barrage, completed in the 1970s. The barrage was built to divert water into the Hooghly River to maintain the navigability of the Kolkata port, but it sharply reduced the dry-season flow reaching Bangladesh.

After years of negotiation, India and Bangladesh signed a comprehensive treaty on 12 December 1996 that established a 30-year water-sharing arrangement and recognised Bangladesh’s rights as a lower riparian state. The treaty governs how the dry-season flow at Farakka is divided between the two countries. With the agreement approaching the end of its term, the two governments have begun discussing its renewal.

Yet the treaty is far from perfect. Critics point out that it divides water at a single point without taking a whole-of-basin approach, and that it does not even include Nepal, the uppermost riparian where much of the Ganges water originates. This narrow scope means the treaty addresses a symptom rather than the full complexity of the shared river.

The unresolved Teesta dispute 🔗

Not every dispute has found a settlement. The Teesta River remains a long-standing sticking point between India and Bangladesh. Bangladesh wants 50 percent of the river’s water during the dry months from December to May, while India has sought a larger share. A complicating factor is that water is a subject involving India’s state governments, and the West Bengal government has resisted any deal it views as harmful to its own farmers. The Teesta shows how domestic politics within one country can stall agreements between nations.

Climate change raises the pressure 🔗

Layered on top of these political disputes is a growing environmental crisis. The Himalayan rivers depend heavily on glaciers and snowmelt, and these are now under threat. The region is under immense stress as global warming melts glaciers and changes rainfall patterns, with reduced flow in the dry season and sudden releases during the monsoon intensifying both scarcity and flooding.

This double threat is especially dangerous for densely populated, low-lying downstream areas. When glaciers retreat, the long-term volume of water becomes uncertain. When rainfall patterns shift, the timing of floods and droughts becomes harder to predict. Fixed water-sharing formulas written decades ago were not designed for a climate this volatile, which is one reason older treaties are increasingly difficult to apply fairly.

The Brahmaputra and the dam race 🔗

Nowhere is the combination of climate stress and geopolitics clearer than on the Brahmaputra. Unlike the Indus and the Ganga, no comprehensive treaty governs the Brahmaputra’s waters, even though it is shared by China, India, and Bangladesh. China sits at the very top of this system as the upper riparian, which gives it considerable influence.

That influence has grown with China’s plans for an enormous hydropower project. China has announced plans to build the world’s largest hydroelectric project at a remote river gorge in Tibet, alarming India, which fears that China could hold back or even weaponise water it depends on. India has responded with its own large hydropower ambitions in the northeast. In mid-2025, India launched a major hydropower initiative to build more than 200 dams in its northeast, especially in Arunachal Pradesh, mirroring China’s project on the Yarlung Tsangpo and signalling an escalating rivalry.

These mega-dams carry serious ecological risks. Large infrastructure in the seismically active Himalayas increases the likelihood of landslides and earthquakes, and altered flows could affect agriculture, fisheries, and sediment movement downstream. Caught at the bottom of this contest, Bangladesh faces the greatest uncertainty of all.

The case for cooperation 🔗

The shared nature of these rivers means that no country can solve its water problems alone. A dam built in Tibet affects Assam; a barrage in West Bengal affects Bangladesh; a diversion in one basin reshapes life hundreds of kilometres away. The existing bilateral treaties, while valuable, were never designed to manage entire river basins or to cope with the speed of climate change.

Many experts argue that the long-term answer lies in moving from narrow, country-to-country deals towards basin-wide cooperation that includes every riparian state and accounts for environmental change. The example of the Mekong River Commission in Southeast Asia, where several nations coordinate over a shared river, is often cited as a possible model. Building such cooperation in South Asia is difficult given the region’s rivalries, but the alternative is a future where water becomes an ever-sharper instrument of conflict.

South Asia’s rivers connect its people in ways that borders cannot easily separate. The same waters that have nourished civilisations for thousands of years now test whether neighbours can manage a shared inheritance wisely. The challenges are real, but so are the opportunities for the region to turn a source of tension into a foundation for lasting stability.

What do you think? Should South Asian countries move away from bilateral water treaties towards a single basin-wide framework that includes all riparian nations? And as climate change makes river flows less predictable, how should old agreements like the Indus Waters Treaty and the Ganges Water Treaty be redesigned for an uncertain future?

References

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