5,000 years of dam history: From ancient engineering to Himalayan hydropower

China has commenced construction of the world’s largest hydropower project by installed capacity on the Tsangpo River near Arunachal Pradesh. This development has raised concerns in India regarding potential downstream impacts, such as altered water flow that could result in frequent droughts or floods. According to limited information released by China, the 38 GW hydropower project is expected to generate 300 TWh of electricity annually, making it three times larger than the Three Gorges Dam on the Yangtze River, currently the world’s largest in terms of installed capacity and reservoir size. While the reservoir capacity of the 60 GW Tsangpo project will be smaller compared to other major global projects, its substantial power generation capability is attributed to an elevation difference of 2.7 km between the dam site and the power plants. Such megastructures are the fallout of the dam building revolutions that started as early as human civilization.

For over 5,000 years, dams have been a cornerstone of human civilization, enabling the rise of agriculture, the growth of cities, and the harnessing of nature's power. These structures represent humanity's enduring quest to manage water—a resource essential for survival and prosperity. From the simple earth embankments of antiquity to the colossal concrete giants of the modern era, the evolution of dams mirrors our technological progress and growing ambition. This article traces the remarkable global journey of dam engineering, with a special focus on India's significant role in this ongoing narrative.

Ancient foundations: The first engineers (3000 BC – 500 AD)

Remnants of Jawa Dam in Jordan (3000 BC)
The earliest dams were feats of communal ingenuity, built to survive millennia. The Jawa Dam in Jordan in 3000 BC, the world’s oldest known dam, was a 9-meter-high stone wall creating a vital reservoir in an arid landscape.

Around 2600 BC, the Sadd-el-Kafara Dam in Egypt was a massive 14-meter-high masonry structure, intended for flood control. Remarkably, it was destroyed by a flood during its construction, serving as an early lesson in hydrological planning.

Concurrently, the Indus Valley Civilization developed sophisticated water management. The city of Dholavira in modern-day Gujarat featured a complex system of 16 dams and reservoirs to channel seasonal water across the desert of Kutch, showcasing an advanced understanding of hydrology.

One of the true wonders of the ancient world was the Great Dam of Marib in Yemen in 1750 BC. This 580-meter-long earthen structure was so critical to the Sabaean kingdom's agriculture that it was successively heightened over 1,500 years, eventually irrigating 100 sq km of desert and supporting a population of 50,000. Its eventual collapse in the 6th century AD is cited as a major factor in the region's decline.

Kallanai Dam (Grand Anicut), India in 100 BC-100 AD, built by the Chola dynasty across the Kaveri River, the unhewn stone structure is the oldest functional water regulator in the world. It brilliantly diverts water to the delta for irrigation, a system that expanded from 280 sq km to over 4,000 sq km by the 20th century.

Rather than a simple barrier, Dujiangyan Irrigation System, China in 256 BC is a masterpiece of system engineering. Using bamboo cages filled with stones, it tamed the Min River by dividing its flow and sediment, providing irrigation for over 5,300 sq km. It remains in use today, a UNESCO World Heritage Site.

Roman innovation and the medieval era: Arches, Mortar, and Hydropower
Roman engineers revolutionized dam design with the introduction of waterproof hydraulic mortar and the arch structure, which allowed for taller, stronger dams.
The Subiaco Dams in Italy in 1st century AD, the tallest of which stood at a staggering 50 meters until the 14th century.

The Glanum Dam in France in 1st century BC is considered the first true arch dam, while the Band-e-Kaisar in Iran in 3rd century AD was a combined dam-bridge that featured the world's first known integration of hydropower, using waterwheels to power water-lifting devices for irrigation.

The scientific revolution in dam engineering (17th – 19th century)
The Industrial Revolution brought new materials and scientific rigor. The invention of Portland cement in 1824 was a pivotal moment, leading to the widespread use of concrete.
Hunt's Creek Dam, Australia in 1856 recognized as the first dam designed using mathematical stress analysis.

The Birth of Hydroelectricity: The first hydroelectric plant began operation in Northumberland, England, in 1878. This was rapidly followed by the Vulcan Street Plant in Wisconsin, USA (1882), the world's first commercial hydroelectric station. By 1889, the U.S. had over 200 such plants, sparking a global energy revolution.

The era of megastructures (20th century – present)
The 20th century ushered in the age of the megadam, symbols of national pride and engineering might.

2080 MW Hoover Dam USA built in 1936

Hoover Dam, USA (1936): A 221-meter-tall arch-gravity colossus, it was the tallest dam in the world for decades and a monument to American ambition during the Great Depression.

Itaipu Dam, Brazil/Paraguay (1984): For decades, Itaipu was the world's largest power producer by output. In 2016, it set a world record by generating 103.1 TWh of electricity, enough to power a country like Paraguay for over a decade.

22500MW Three Gorges Dam on the Yangtze River built in 2008 in China

Three Gorges Dam, China (2008): The current titan, with a capacity of 22,500 MW, is the world's largest power station. After the extensive monsoon rainfalls of 2020, the dam produced nearly 112?TWh in a year, breaking the previous world record of ~103?TWh set by the Itaipu Dam?in 2016. Its 39.3 billion cubic meter reservoir is so massive that NASA calculated it?slows the Earth's rotation by 0.06 microseconds.

Global distribution of large dams: A strategic overview

Today, total number of dams globally (including small, large, and hydropower dams) is estimated to be well over 1 million, though only a fraction is formally registered or monitored. There are over?58,000 large dams worldwide (defined as over 15 meters high or storing more than 3 million cubic meters of water). Their distribution highlights regional priorities:

China (23,000 dams): The global leader, focused on hydropower and flood control, with massive projects like the South-North Water Diversion Project.

United States (9,200 dams): A pioneer in multipurpose dams, many built in the mid-20th century, now facing challenges of aging infrastructure.

India (5,700 dams): Home to the world's third-largest number of dams, crucial for irrigation in its monsoon-driven climate. Key projects include the?Bhakra Nangal?and?Sardar Sarovar?dams.

Other Key Players: Brazil, Canada, Russia, Japan, and Turkey all have extensive dam networks tailored to their geographical and economic needs.

India’s dam legacy: From Kallanai to Tehri dam

India’s relationship with dams is both ancient and transformative. The enduring Kallanai Dam, built around 100 BC by the Chola dynasty across the Kaveri River in Tamil Nadu, stands as one of the oldest water-regulation structures still in use today. This stone masonry marvel was designed to divert river water for irrigation, and its legacy continues to shape agricultural prosperity in the delta region.

South India has long been a cradle of hydraulic engineering. During the colonial era, the Mullaperiyar Dam, constructed between 1887–1895 in Kerala became a landmark gravity dam, built to divert water eastward to Tamil Nadu. Similarly, Karnataka saw the construction of the Krishnaraja Sagar Dam in 1911 and the Mettur Dam in Tamil Nadu in 1925, both pivotal in transforming irrigation and power generation in the region. These projects laid the foundation for modern dam-building in peninsular India, where water management was essential for monsoon-dependent agriculture.

Post-independence, dam construction became a cornerstone of national development. Bhakra-Nangal Dam in Himachal Pradesh, commissioned in 1963, is the second tallest dam in Asia. The 226 meters high and 518.25 meters long dam created the 90 km long reservoir known as "Gobind Sagar" stores up to 9.34 billion cubic metres of water. In terms of storage of water, it is the third largest reservoir in India, the first being Indira Sagar dam (2005) in Madhya Pradesh with capacity of 12.22 billion cubic meters and the second being Nagarjuna Sagar Dam (1967) in Telangana with 11.472 billion cubic metres.

The most iconic dam in Gujarat is the Sardar Sarovar Dam on the Narmada River, one of the largest concrete gravity dams in the world.  Conceived in 1946 and formally initiated in 1961 by Prime Minister Nehru, the project faced decades of environmental and social challenges before its inauguration in 2017 by Prime Minister Narendra Modi. The dam is 138.68 meters high, with a reservoir capacity of 9.497 billion cubic meters, and supplies water and electricity to Gujarat, Madhya Pradesh, Maharashtra, and Rajasthan.

The Koyna Hydroelectric Project, completed in 1964 in Maharashtra, is the second largest hydroelectric power plant in India, with a total installed capacity of 1,960 MW. The Koyna River provides significant electricity generating capacity for the region. The dam is 103.2 meters high and 807.2 meters long, and its reservoir holds 2.981 billion cubic meters of water.

1000 MW Tehri Dam on the Bhagirathi River built in 2006 in India

The Tehri Dam in Uttarakhand, commissioned in 2006, exemplifies the modern ambitions of power and water management. Standing at 260.5 meters, it is India’s tallest dam and a rock-and-earth-fill embankment structure. Tehri Hydropower Complex with installed capacity of 2,400 MW with components Tehri Dam (1000 MW), Tehri Pumped Storage Plant (1,000 MW) and Koteshwar Dam (400 MW) is the largest hydro complex in India. Designed for multipurpose use, it provides irrigation and drinking water to millions. It generates approximately 3 TWh of electricity annually, playing a vital role in North India’s energy grid.

India’s push towards harnessing its hydropower potential is especially pronounced in the northeastern region, with Arunachal Pradesh rapidly establishing itself as a central player in this sector. Arunachal Pradesh alone has hydropower potential of 50328 MW, 40% of the country’s potential whereas only 1115 MW (2.21%) is operational.

A flagship example of this momentum is the Dibang Multipurpose Project on Dibang River, which has been under construction since 2024. Set to become the tallest dam in India at 278 meters, the Dibang Dam epitomises the scale and ambition of the country’s hydropower ambitions. The project is designed with an installed capacity of 2,880 MW, significantly bolstering the regional and the national electricity supply with green, renewable energy. Upon completion, it is expected to generate approximately 11.223 terawatt-hours (TWh) of electricity each year, thereby playing a crucial role in strengthening the national energy grid with sustainable power. Beyond power generation, the Dibang Multipurpose Project serves a vital function in flood management. Its strategic location and design will enable it to fully control the floods created by the Dibang River downstream, protecting communities and agricultural lands that are vulnerable to seasonal inundation. Thus, the project not only contributes to India’s energy security but also enhances resilience against natural disasters in the region.

From 2007 to 2011, the Idu Mishimi community of Dibang Valley opposed the 2880 MW Dibang Multipurpose project due to concerns over low compensation and environmental impact. After the introduction of the Right to Fair Compensation and Transparency in Land Acquisition, Rehabilitation and Resettlement Act, 2013, the community accepted the revised compensation and recognized the potential benefits of hydropower for locals and the state.

The Subansiri Lower Dam, strategically situated on the Arunachal-Assam border across the Subansiri River—a prominent tributary of the Brahmaputra—is approaching completion. This impressive concrete gravity dam stands at a height of 116 metres and is designed to generate 2,000 MW of electricity. In addition to power generation, the dam will play a crucial role in partially controlling the floods caused by the Subansiri River, thereby providing significant relief to downstream communities. Construction of the Subansiri Lower Dam commenced in 2005. However, the project encountered substantial delays owing to civic protests, which primarily centred on environmental concerns affecting downstream regions in Assam. As a result, construction was halted from 2011 to 2019. Work on the dam resumed in October 2019, following a prolonged period of engagement with stakeholders and renewed commitment to addressing environmental and social issues. Once fully operational, the Subansiri Lower Dam will contribute 7.421 terawatt-hours (TWh) of clean energy to the nation’s grid. This will not only enhance India’s renewable energy portfolio but also support the broader objective of sustainable development in the North-East region.

In 2023, the Union Cabinet approved 13 major dam projects across Arunachal Pradesh, targeting a combined capacity of 12,717 MW. These include Subansiri Upper (2,000 MW) and Subansiri Middle (1,800 MW) dams, Kalai-II Dam (1,200 MW) on the Lohit River, Etalin Dam (3,097 MW) in Dibang Valley with 4 others on its tributaries and 5 projects including Naying Dam (1000 MW0 and Tato-II Dam (700 MW) on the Siyom River in Shi Yomi district. Development of these projects will contribute towards achieving the declared Nationally Determined Contribution (NDC) target of achieving 500 GW non-fossil energy capacity of India by 2030. Hydro Power will also be an effective contributor to the objective of achieving Net Zero carbon emissions by the year 2070. These projects are also expected to create huge employment opportunities in the region and boost the local economy as well as foster skill development and technical expertise in the region.

India is moving forward with the development of the Siang Upper Dam, a significant hydropower and water management project. The proposed dam is set to have an installed capacity of 11 GW, making it a major contributor to the country's renewable energy ambitions. A defining feature of this project is its large storage reservoir, which will be able to hold up to 9.2 billion cubic metres of water. The central goal of the Siang Upper Dam initiative is to address and mitigate environmental challenges through robust water management strategies. This becomes especially crucial in the wake of China’s planned construction of a 60 GW dam upstream, scheduled for completion in 2033. By advancing the Siang Upper Dam, India seeks to strengthen its resilience to cross-border hydrological alterations and ensure the long-term security of water resources for downstream communities.

The proposed Siang Upper Dam has sparked widespread protest among the Adi community, whose ancestral lands, vibrant towns, villages, fertile agricultural fields, and rich forest areas now face the threat of submergence. The displacement of a large number of Adi people has raised serious concerns, especially as the compensation packages offered fall short of their expectations and needs. While the Land Acquisition and R&R Act of 2013, along with Arunachal Pradesh’s R&R Policy of 2008, provide a framework for fair compensation, their true potential can only be realized if the affected families receive enhanced support. Instead of offering modest houses of just 60 sqm or a mere ?2 lakh—which are inadequate for permanent resettlement—there is a pressing need for more substantial and dignified rehabilitation measures that honour the cultural and economic realities of the tribal people of Arunachal Pradesh.

These initiatives of comprehensive dam building not only aim to boost India’s renewable energy capacity and water management but also promise regional development, improved connectivity, and strategic resilience in the sensitive border state.

Conclusion

The history of dams stands as a testament to human resilience and ingenuity. From their earliest incarnations in the arid realms of ancient Yemen, where communities harnessed scarce water resources for survival, to the modern era marked by silicon-controlled power grids, dams have continually shaped both landscapes and the destinies of entire societies. Over centuries, these engineering marvels have been at the heart of civilisational progress, enabling agricultural expansion, supporting burgeoning populations, and powering economic growth.

In the contemporary world, the significance of dams has grown even more pronounced. As humanity confronts the intertwined challenges of climate change, water scarcity, and the escalating demand for clean, renewable energy, the role of dams has become increasingly complex and vital. No longer are they merely symbols of technological ambition; they are now pivotal players in the global pursuit of sustainable development.

The central challenge for the 21st century lies in harmonising the bold engineering achievements of the past with a renewed commitment to ecological sustainability and social responsibility. It is essential that the design, construction, and operation of dams incorporate the imperatives of environmental stewardship and the well-being of affected communities. Only by striking this delicate balance can these monumental structures continue to serve humanity, not just in the present, but for generations to come. (The author is a consultant in hydropower development)