Nepal floods show the risk; China’s mega-dam raises bigger questions for India | India News
The rain came down relentlessly, turning quiet mountain streams into raging torrents and narrow roads into muddy rivers. Across Nepal, floodwaters and debris swept through homes, roads and hydropower facilities, leaving behind broken bridges, stranded communities and villages cut off from the outside world.In the mountains, where steep slopes already make life precarious, swollen rivers, landslides and collapsing rock can quickly turn a natural hazard into a cascading disaster.For communities living along narrow Himalayan valleys, a sudden rush of water, ice and debris can leave little time to escape.The recent flash floods in Nepal have brought these vulnerabilities sharply into focus. Search teams have battled heavy rain and thick layers of debris while looking for people believed to be trapped in tunnels, hydropower projects and underground power facilities along the Bhotekoshi River.But the devastation has also raised a larger question: what happens when the already fragile Himalayan environment is combined with increasingly large infrastructure projects, including dams, tunnels, highways and hydropower facilities?That question has particular significance for India because the Himalayas are not confined by political boundaries. Rivers, glaciers, mountain systems and geological faults cut across China, Nepal, Bhutan and India. A disaster originating in the high mountains can therefore have consequences far beyond the point where it begins.It is against this backdrop that China’s massive hydropower project on the Yarlung Tsangpo, known downstream as the Brahmaputra, has come under renewed scrutiny.The project, being built in Tibet’s Medog County at the dramatic Great Bend of the river, is expected to become the world’s largest hydropower project.Its location, however, adds another layer of concern. The project sits in one of the world’s most geologically challenging regions, marked by steep Himalayan terrain, active faults, earthquakes, landslides, glaciers and extreme weather.These natural risks make the dam not just a massive engineering undertaking, but also a strategically sensitive project located upstream of one of India’s most important rivers.
Why the Brahmaputra is so important
China formally began construction of the Yarlung Tsangpo River Lower Reaches Hydropower Project in July last year. The mega-dam is being built in Medog County, near the river’s Great Bend, where the Yarlung Tsangpo makes a dramatic U-turn before entering India.China calls the Brahmaputra the Yarlung Tsangpo. After crossing into Arunachal Pradesh, the river is known as the Siang or Dihang before flowing through Assam and eventually entering Bangladesh, where it is known as the Jamuna.The project is located in one of the world’s deepest river gorges. Over a stretch of about 50 kilometres, the river drops nearly 2,000 metres, creating enormous potential for hydropower generation.The project is expected to comprise five cascade hydropower stations and generate more than 300 billion kilowatt-hours of electricity annually, more than three times the annual generation of China’s Three Gorges Dam, according to reports cited in the material.With an estimated cost of around 1.2 trillion yuan, or about $167.8 billion, it is set to rank among the world’s most expensive infrastructure projects. Chinese Premier Li Qiang has described it as the “project of the century”.But the significance of the project extends far beyond its size or power-generation capacity.The Brahmaputra is far more than a river. It is an economic, ecological and strategic lifeline for millions of people across the eastern Himalayas and South Asia.Originating on the Tibetan Plateau, the river flows through China, India and Bangladesh before emptying into the Bay of Bengal. It stretches for roughly 2,900 kilometres and drains a basin of about 580,000 square kilometres shared by China, India, Bhutan and Bangladesh.One of the world’s largest rivers by discharge, the Brahmaputra is also known for its vast braided channels. Its waters support agriculture, irrigation, fisheries, transport, hydropower and ecosystems across the region.For India, the river becomes particularly important after entering Arunachal Pradesh and Assam. The Brahmaputra and its tributaries sustain communities, farmland and ecosystems across the Northeast, while also bringing the region some of its most destructive floods.That is what makes China’s position upstream so significant for India. Beijing cannot simply stop the Brahmaputra from flowing into India. By the time the river reaches Arunachal Pradesh, it has already begun receiving substantial water from rainfall and tributaries, with flows rising sharply during the monsoon.The concern is therefore less about China being able to permanently cut off the river and more about whether a large upstream hydropower system could influence the timing and volume of flows.The operation of reservoirs, tunnels, power stations and other infrastructure could potentially affect seasonal water releases.For India, this raises questions not only about water security, but also about access to reliable hydrological information and the ability to prepare for sudden changes in river flows, particularly during periods of heavy rainfall or extreme weather.
What did experts find
The study, published in the Chinese-language journal Sedimentary Geology and Tethyan Geology and supervised by the state-owned China Geological Survey, examined the Paizhen Fault in Tibet.According to the researchers, the fault has remained highly active since the Pleistocene epoch, or Ice Age, and continues to show evidence of geological activity. Geological dating of ancient lake sediments suggests that movement along the fault occurred as recently as about 9,500 years ago.The researchers warned that repeated movement along the fault had fractured and weakened surrounding rock formations. This could make major engineering structures in the area more vulnerable to geological hazards.“The Paizhen area is located within the reservoir area of the Yarlung Tsangpo downstream hydropower station,” the paper said.The researchers said the fault could have a significant impact on the structural stability and construction of nearby infrastructure, including dams, roads, bridges and tunnels, as well as the reservoir area.They also cited the magnitude 6.9 earthquake that struck the Milin area of Tibet in 2017 as evidence that the region remains seismically active.“Under regional seismic action, landslides and collapses can easily be induced, threatening the safety of engineering facilities and personnel,” they said.The scientists recommended reinforcing vulnerable slopes and installing retaining structures to reduce the risk of landslides and collapses during construction and after the project becomes operational.The research was conducted by scientists from the Chengdu University of Technology, the Civil-Military Integration Centre of the China Geological Survey, and the Middle Yarlung Zangbo River Natural Resources Observation and Research Station.The findings are significant because they come from Chinese researchers working within China’s own geological and scientific institutions.They do not establish that the project is unsafe or that a disaster will occur. But they underline the difficulty of constructing and operating a mega-project in a region where geological instability is an inherent feature of the landscape.
Is China capable of ‘stopping’ the Brahmaputra?
The idea that China could simply stop the Brahmaputra from reaching India is often overstated. Srijan Pal Singh, author, former Advisor for Policy and Technology to former President APJ Abdul Kalam, CEO of Homi Lab and founder of Kalam Centre, said the more realistic concern was China’s ability to influence the timing of flows and the lack of transparency surrounding the management of the river.“The real concern, therefore, is less about China cutting off the Brahmaputra and more about transparency, reliable data-sharing, and India’s ability to anticipate and manage sudden changes in flow,” Singh told TOI.He said that while a significant share of the Brahmaputra’s annual flow is generated within India through monsoon rainfall and tributaries, the lean-season flow originating in Tibet remains strategically important.Singh also cautioned against viewing the project solely through the lens of water diversion. “Any large dam on an international river has both economic and strategic implications,” he said.He added that control over upstream infrastructure could itself create strategic influence even without physically restricting the river.“It is not necessary to stop the flow of water for leverage to exist. The ability to regulate flows, collect hydrological data, or alter the timing of water releases can shape the decisions of downstream countries, particularly during periods of tension or extreme weather,” he said.The distinction matters because the principal challenge for India is not simply the quantity of water but the predictability of that water.During the monsoon, India needs accurate information about upstream river conditions to prepare for floods. During the dry season, information about river flows becomes equally important for agriculture, water management and ecosystems.
What India is concerned
India’s concerns over the Medog project go beyond water security. The Yarlung Tsangpo flows from Tibet into Arunachal Pradesh. A mega infrastructure project on the river, close to the disputed border, therefore has an inevitable strategic dimension.The biggest concern may ultimately be geological. The project lies in the eastern Himalayas, along the collision zone of the Indian and Eurasian tectonic plates.The region is marked by active faults, steep slopes, fractured rock, earthquakes and frequent landslides, all of which pose challenges for a mega-dam and the infrastructure needed to support it.The 1950 Assam-Tibet earthquake, estimated at magnitude 8.7, remains a stark reminder of the region’s seismic potential. It caused widespread destruction across Tibet and Assam and killed thousands of people.The Chinese geological study has added to concerns over the site. Researchers found that repeated fault activity had weakened rock formations and recommended measures such as reinforcing vulnerable slopes and constructing retaining structures to reduce landslide risks.Writing in Project Syndicate, Brahma Chellaney, professor emeritus of strategic studies at the New Delhi-based Centre for Policy Research, said the warning from Chinese scientists was particularly significant.“The geologists conclude that the terrain has a ‘loose structure and weak cohesion’ and warn that fault movement or an earthquake could easily trigger large-scale instability, threatening both the reservoir and surrounding infrastructure,” Chellaney wrote.“Ironically, the latest evidence suggests that China’s scientific establishment understands the dangers of building the unprecedented super-dam more clearly than its political leadership appears willing to acknowledge. Now that China’s own geologists have raised the alarm, Beijing must embrace transparency and accept transboundary responsibilities before a potential water bomb is fully assembled upstream,” Chellaney wrote on X.There are also concerns about the possibility of reservoir-triggered seismicity, in which the weight of water stored behind a large dam can affect pressure and stress along existing faults. China’s 2008 Wenchuan earthquake has often been cited in this debate.Scientists have differed over the extent of the Zipingpu reservoir’s role, but some studies have suggested that the reservoir may have contributed to triggering or advancing seismic activity.The concern, therefore, is not only whether an earthquake could damage the dam. A major earthquake could also trigger landslides, rockfalls and failures across the surrounding infrastructure.Singh said advances in engineering have significantly improved dam safety but cannot completely remove geological risks.“Modern engineering can design dams to withstand very strong earthquakes. Advanced materials, flexible structural designs and continuous monitoring systems have greatly improved dam safety. However, no engineer can completely eliminate geological risk,” he said.The region has also witnessed glacier collapses and landslides. Sayanangshu Modak, a researcher at the University of Arizona, cited the massive 2021 glacier collapse near the Great Bend, which temporarily blocked the river and sharply raised water levels, SCMP reported.Long-term safety, he added, would depend on continuous monitoring, regular assessments and the ability of the project to withstand not only earthquakes but also landslides, rockfalls and extreme weather events.
What does Nepal’s recent disaster show?
The August 26 disaster in Nepal offers a stark example of how Himalayan hazards can interact. The evidence available so far points to a glacier-rock collapse and massive debris avalanche rather than a conventional monsoon flood.The collapse triggered an ice-rock avalanche that temporarily blocked the Bhotekoshi River, sending a huge volume of ice, rock, mud and water downstream and causing widespread destruction.The avalanche reportedly travelled at around 50 metres per second. Such events demonstrate the cascading nature of Himalayan disasters.A glacier collapse or earthquake can trigger a landslide; a landslide can block a river; and the sudden failure of that blockage can send a destructive surge of water and debris downstream.Infrastructure located along the river corridor, including roads, bridges, hydropower stations and settlements, can then become part of the disaster chain.The 2015 Nepal earthquake provided another warning. Research following the quake found that earthquake-triggered landslides were a major cause of damage to hydropower infrastructure and estimated that about a quarter of existing, constructed and planned Himalayan hydropower projects faced a high probability of moderate-to-severe earthquake damage.
How climate change is adding to the risk
Climate change is adding another layer of uncertainty to an already fragile landscape. Glaciers across the Hindu Kush Himalaya are losing ice, while permafrost degradation can destabilise high-altitude slopes. Glacial lakes are expanding in some areas, while changing rainfall patterns are increasing the risk of extreme precipitation.Nepal has thousands of glacial lakes, some of which can potentially produce catastrophic Glacial Lake Outburst Floods, or GLOFs.Climate change does not cause every landslide, avalanche or flood. But it can alter the conditions that make such events more likely and make their timing and scale harder to predict.That creates a particular challenge for hydropower development in the Himalayas.As Himanshu Thakkar, coordinator of the South Asia Network on Dams, Rivers and People, has argued, environmental, social and disaster-risk assessments need to account for the specific characteristics and historical hazards of individual valleys.
The ecological concerns
The Medog project is being built in an exceptionally sensitive landscape. The Great Bend of the Yarlung Tsangpo is marked by steep slopes, glaciers, high rainfall, unstable rock formations and active tectonic structures.Geologist Fan Xiao has described the Yarlung Tsangpo Grand Canyon as a rare biodiversity hotspot in a geologically unstable region.He has warned that multiple hydropower stations, high dams, reservoirs and extensive tunnels could increase landslide risks and cause long-term environmental damage.The impact of such a project is also unlikely to be limited to the dam itself. Roads, tunnels, bridges, transmission lines, worker settlements and other supporting infrastructure will be needed to build and operate the project.Each intervention can alter slopes, drainage patterns and river corridors, creating additional pressure on an already fragile ecosystem.The ecological consequences are particularly difficult to predict over decades, especially as climate change continues to reshape the Himalayan environment.The project’s location also raises questions about its strategic implications for India. The concern is not simply that the dam could alter river flows. The infrastructure required to build and operate such a massive project could itself have strategic value.“Such a large project requires roads, tunnels, bridges, power infrastructure and communication networks. These assets can improve access to remote border areas and support logistics in peacetime as well as during a crisis,” Singh said.He added that while the project alone would not alter the military balance along the Line of Actual Control, it could increase China’s long-term presence near the border and improve its understanding of the terrain and river system.“The strategic balance in the eastern sector will continue to depend primarily on military capability, border infrastructure, surveillance and operational readiness on both sides,” he said.Singh also noted that India has accelerated hydropower development downstream as part of its effort to strengthen water utilisation.Some analysts, however, see the project as giving Beijing additional diplomatic leverage because of its upstream position. Shanghai-based security analyst Ni Lexiong told SCMP that the dam could “effectively create geopolitical leverage vis-a-vis India diplomatically”.Others take a more cautious view. Liu Zongyi, a senior fellow at the Shanghai Institutes for International Studies, argued that concerns about China’s ability to manipulate river flows are overstated and that the project would not fundamentally change India-China relations.For India, therefore, the challenge is broader than the question of whether China can control the Brahmaputra.It is about managing the combined risks of upstream infrastructure, uncertain hydrological flows, seismic hazards, climate change and the project’s proximity to a sensitive border.
Dam can affect Earth’s rotation
Earth’s rotation is not perfectly constant. Natural forces such as earthquakes, the Moon’s gravitational pull, melting ice and the movement of water can subtly change how quickly the planet spins. Even human-made structures can have a measurable, though extremely tiny, effect.China’s Three Gorges Dam provides one striking example. When its vast reservoir is filled, the enormous volume of stored water redistributes mass on Earth. This increases the planet’s moment of inertia, causing it to rotate very slightly more slowly.Nasa scientist Dr Benjamin Fong Chao calculated that the full reservoir could lengthen the day by about 0.06 microseconds, or 60 billionths of a second, while shifting the position of the poles by roughly two centimetres, BBC reported.The change is far too small to have any noticeable effect on everyday life. But it demonstrates how moving billions of tonnes of water can produce a measurable change in the planet’s physical dynamics.
China calls Brahmaputra project safe
Beijing has repeatedly sought to reassure downstream countries about the safety of the Medog project. An official statement issued in December 2024 said the project was safe and prioritised ecological protection.“Through extensive geological explorations and technical advancements, a solid foundation has been laid for the science-based, secure, and high-quality development of the project,” it said.Chinese officials have also maintained that the project follows the highest industry standards and would not negatively affect downstream countries.A Chinese foreign ministry spokesperson said China was highly responsible in developing cross-border rivers and had extensive experience in hydropower construction. Beijing has also said it would maintain communication with downstream countries and cooperate on disaster prevention and mitigation.The recent geological study does not necessarily contradict those assurances in the sense of proving that the dam is unsafe. But it does demonstrate that the geological challenges identified by outside observers are also being studied by Chinese scientists themselves.
The problem of hydrological data
For India, one of the most important lessons from the past is the importance of reliable river-flow information. China suspended the sharing of hydrological information on the Brahmaputra and Sutlej during the 2017 flood season.In a written reply in the Rajya Sabha on February 8, 2018, the Ministry of External Affairs said China had not provided hydrological information on the Brahmaputra and Sutlej despite existing bilateral agreements. Beijing attributed the interruption to “technical reasons”.The suspension occurred during the 73-day Doklam standoff between India and China, although Beijing maintained that the interruption was related to the upgrading of hydrological monitoring stations.China resumed Brahmaputra hydrological data sharing in May 2018. The original agreement on sharing hydrological information for the Brahmaputra was signed in 2002 and subsequently renewed.
Why is transparency important?
For India and Bangladesh, the challenge is therefore broader than whether China can control the Brahmaputra. It involves the combined risks of upstream infrastructure, seismic hazards, climate change, ecological damage and uncertainty over future water flows.The sheer scale of what China has called the “project of the century” has also increased calls for greater transparency about the dam’s design, geological assessments, reservoir operations and possible downstream impacts.International principles governing transboundary rivers generally require countries to exchange relevant information, avoid significant cross-border harm and consult on projects that could affect other states.Chellaney has argued that China’s limited disclosure about the project is particularly concerning given its potential consequences for downstream countries.Singh said India’s immediate priority should be stronger mechanisms for information-sharing.“India’s first priority should be to strengthen institutional mechanisms for the regular exchange of hydrological data, especially during the monsoon season,” he said.Chellaney argued that the warnings raised by Chinese researchers should prompt greater international scrutiny.“When scientists working under a communist regime issue such warnings, the international community must pay attention,” he wrote.For India, the Medog project is therefore not just a question of water. It is a question of how to manage a combination of geological, environmental and strategic risks on a river that crosses national borders and supports millions of people downstream.
A Himalayan warning for India
The recent disaster in Nepal has shown how quickly the Himalayas can turn from a source of water and energy into a source of extraordinary danger.A glacier can collapse. Rock can fall into a river. A temporary blockage can form. The blockage can breach. A wall of water and debris can then travel through a narrow valley at enormous speed.When roads, bridges, tunnels, hydropower plants and settlements occupy that same valley, the consequences multiply. This is the central challenge facing Himalayan development.The issue is not whether Nepal, India or China should develop their mountain regions. Millions of people depend on infrastructure, electricity, connectivity and economic development.The question is whether that development is being planned according to the realities of a young, unstable and rapidly warming mountain system.For India, the question becomes even more consequential because the country’s major rivers originate or flow through these mountains before reaching the plains.China’s Yarlung Tsangpo project therefore represents more than a massive power-generation scheme. It raises questions about seismic safety, river-flow management, ecological change, data sharing and strategic influence.The Himalayas are already under pressure from climate change, earthquakes, landslides, glacier retreat and intense rainfall. Adding more infrastructure without accounting for cumulative risk could create new vulnerabilities even while addressing existing strategic concerns.The immediate cause of Nepal’s August 26 disaster may have been a glacier-rock collapse. But the larger warning is unmistakable: the Himalayas are becoming an increasingly dangerous place to ignore geological and climatic limits.As Nepal Prime Minister Balendra Shah said in his September 2 address to the House of Representatives, “climate change is the world’s shared responsibility, and that Nepal must forcefully campaign for climate justice and international financial compensation rather than simple post-disaster aid”.He linked the recent catastrophic flash floods in Rasuwa to a warming climate and described the disaster as a warning for the wider Himalayan region and the world.That warning extends beyond Nepal.The Brahmaputra does not recognise borders. Neither do earthquakes, glaciers, landslides or extreme weather. As China moves ahead with the Medog mega-project and India expands its own hydropower infrastructure, the real test will be whether development can keep pace with the risks of a rapidly changing Himalayas.
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As construction of the Medog project advances, the questions will become increasingly difficult to avoid: Can the world’s largest hydropower project remain safe in one of the world’s most geologically active landscapes? Can downstream countries receive timely and reliable information about changes in river flows?And can infrastructure development in the Himalayas be pursued without turning natural hazards into human-made disasters?For now, there are no easy answers. But the floods in Nepal have made one thing clear. In the Himalayas, the consequences of getting the balance between development and nature wrong can travel far beyond the valley where the decision was made.
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