By Nirmal P. Acharya

This century, China has undertaken two remarkable projects in the Himalayas: the hydropower project on the lower reaches of the Yarlung Zangbo River and the China-Nepal Railway. On July 19 this year, China announced the official commencement of the hydropower project on the lower reaches of the Yarlung Zangbo River. Chinese Premier Li Qiang attended the commencement ceremony at the construction site in Tibet. 

The official start of construction of the water conservancy project in the lower reaches of the Yarlung Zangbo River (usually referring to the Metog Great Bend area) is indeed a major milestone in the history of water conservancy projects in China and even the world. This project is expected to achieve or challenge multiple breakthroughs in the history of water conservancy, mainly reflected in the following aspects:

1. Unprecedented scale and difficulty:

- The world's largest single hydropower station (planned installed capacity): The theoretical reserve of hydropower resources in this area is extremely rich. It is estimated that the total installed capacity of the planned Metog Hydropower Station (or developed in multiple stages) may reach the level of 40 million to 60 million kilowatts, far exceeding the current world's largest Three Gorges Hydropower Station (22.5 million kilowatts) and Brazil's Itaipu Hydropower Station (14 million kilowatts). This will be the largest single hydropower station ever built by humans.

- Super engineering cluster: The project not only includes a giant hydropower station, but also involves ultra-long deep-buried water diversion tunnels, ultra-high dams (possibly over 300 meters), super-large underground workshops, etc., forming an extremely complex super engineering cluster.

- Challenges from extreme geographical environment: The project is located on the edge of the Qinghai-Tibet Plateau and in one of the world's most complex geological structures and most intense seismic activity areas (the Himalayan seismic zone). High altitude, large drop, deep canyons, steep slopes, complex geology (such as high ground stress, rock bursts, water gushing, fault fracture zones), etc., make the survey, design, and construction difficulty unparalleled in the world.

2. Ultra-long deep-buried water diversion tunnels:

- To utilize the huge natural drop (about 2000-3000 meters) at the Great Bend, it is likely necessary to build deep-buried water diversion tunnels with a length of more than 50 kilometers or even 100 kilometers.

- The burial depth of these tunnels will reach more than 2000 meters, or even deeper. Building ultra-long tunnels under such conditions of deep burial, high ground stress, high water pressure, and extremely complex geology is an unprecedented challenge in the history of human engineering, which will greatly promote the survey, design, construction (such as TBM technology), safety monitoring, and disaster prevention and control technologies of deep-buried and long tunnels.

3. Ultra-high dam construction technology:

- According to possible development plans, it may be necessary to build 300-meter-level or even higher extra-high dams (such as arch dams or rockfill dams). Building such high dams in areas with such high-intensity earthquakes and complex geological conditions puts unprecedented demands on dam seismic design, foundation treatment, material performance, and construction technology.

4. Giant underground cavern groups:

- Due to the extremely limited ground space and complex geological conditions, the main powerhouses, transformer rooms, water diversion surge chambers, etc., will be largely arranged underground, forming one of the world's largest underground cavern groups in scale. The control of excavation span, height, and stability is extremely difficult.

5. Revolutionary improvement in clean energy supply:

- After the full completion of the project, its annual power generation is expected to reach twice or more that of the Three Gorges Hydropower Station (the Three Gorges has an annual power generation of about 100 billion kilowatt-hours). This will be a key support for China to achieve its "dual carbon" goals (carbon peak and carbon neutrality), providing the country with a huge amount of stable, renewable, zero-carbon emission clean energy, and having epoch-making significance for optimizing the national energy structure and ensuring energy security.

6. Comprehensive guarantee for ultra-large-scale projects in plateau extreme environments:

- Carrying out such a large-scale project construction on the edge of the Qinghai-Tibet Plateau with thousands of meters above sea level, extremely inconvenient transportation, and a sensitive ecological environment, the complexity and difficulty of material transportation, personnel guarantee, medical security, environmental protection, and construction organization management are unprecedented. This in itself is a huge systematic breakthrough.

7. A benchmark for ecological protection and transnational river coordination (potential breakthroughs and challenges):

- The project is located in the ecologically extremely sensitive Qinghai-Tibet Plateau and the upper reaches of the transnational river (Brahmaputra), and its environmental impact assessment and ecological protection measures have attracted international attention. How China implements world-leading ecological protection measures (such as ensuring the ecological flow of water release, fish protection, soil and water conservation, biodiversity protection) while developing huge energy, and conducts effective hydrological data sharing and coordination with downstream countries (mainly India and Bangladesh), will be a major test of its global environmental governance responsibilities and capabilities. If it can successfully balance development and protection and coordinate international concerns, it will become a world-class benchmark.

In summary, the main breakthrough points of the Yarlung Zangbo River lower reaches water conservancy project are as follows:

- The largest in scale: The planned installed capacity is the largest in the world.

- The highest in difficulty: Building a super project in an environment with extremely complex geology, earthquakes, and geography.

- Challenges to technical limits: Breakthroughs and applications of key technologies such as ultra-long deep-buried tunnels, ultra-high dams, and giant underground cavern groups.

- Contribution to clean energy: Providing an unprecedented amount of zero-carbon electricity.

- Plateau engineering guarantee system: The comprehensive ability to implement ultra-large-scale projects in extreme environments.

- Ecology and international coordination (both challenges and opportunities): How to balance development and protection in sensitive areas and handle transnational river relations.

This project is not only a culmination and peak challenge of China's water conservancy and hydropower technology, but also a landmark event in the history of human conquest of nature and utilization of clean energy. Its construction process will surely promote leapfrog development in multiple fields such as related science and technology, engineering management, and environmental protection.

If we were to compare the construction difficulties of the China-Nepal Railway and the water conservancy project in the lower reaches of the Yarlung Zangbo River, the construction difficulty of the China-Nepal Railway may actually be greater.

The China-Nepal Railway is not only the construction of a physical corridor but also a challenge to the engineering limits of the Earth's Third Pole. Its construction difficulty far exceeds that of conventional water conservancy projects, requiring the integration of multidisciplinary innovations in geology, climate, and humanities. If successfully completed, it will become a pinnacle project of the "Belt and Road Initiative", but every step forward will need to face the natural power of the Himalayas. The game between human engineering wisdom and the mountains has reached an unprecedented intensity here.

However, China has long been known as the "Infrastructure Maniac," and one day it may suddenly announce the official start of construction on the Tibet section of the China-Nepal Railway.