In China everything seems to be bigger.
Cities, highways, and of course: Megaprojects.
And one project, in particular, stands
out: the largest and most powerful dam in the world. With a reservoir so massive
it even slows down the Earth’s rotation, the sheer scale of this structure is unlike
anything the world has ever seen before.
It is an inspiring but dangerous structure at
the same time. While it generates electricity for millions of people, it is also
repeatedly criticized for being at risk of collapse. But what lies behind it,
is the dam really in danger? In this video, we’ll explore one of the biggest megaprojects
in the entire world — the Three Gorges Dam.
At 2.3 kilometers along its longest point, and
towering at more than 180 meters, the Three Gorges Dam in Hubei is massive. It sits across the mighty
Yangtze River and holds back a gigantic reservoir more than 600 kilometers across. This reservoir
alone spans over an area larger than the entire island nation of Singapore. But the structure
itself isn't the most impressive feature.
With a total installed capacity of 22.5 gigawatts,
it is also the world’s largest power station of any kind. By comparison, the Grand Coulee Dam,
America’s most powerful, is only a quarter of the Three Gorges’ capacity. And even nuclear
power plants cannot compete with its capacity.
Operating at its theoretical limit, the entire
facility is capable of providing power to more than 4.5 million people all year round.
But aside from generating a constant supply of clean and renewable energy
to millions of people, there was another crucial reason why it was built:
Villages and cities surrounding the Yangtze river have repeatedly fallen victim to heavy
flooding. Minor floods happen almost every year during the rainy season. The biggest
problem, however, are major and long-lasting floods that are difficult to predict.
It is estimated that around 90 years ago, the deadliest among them claimed
between 3.7 and 4 million lives (2). So something needed to be done.
Therefore, the concept for an enormous dam that could control the
flow of the Yangtze was developed.
Today, with more than 400 million
people living around the area (3), this structure potentially saves many lives.
The Three Gorges has the capability of preventing catastrophic flooding further downstream in
cities such as Wuhan and Shanghai. This is made possible by storing huge volumes of water
inside the reservoir during rainy seasons and controlling the amount of water that flows out.
However this system isn’t flawless. During heavy rains in 2010 for example, they were
forced to release water to keep the reservoir at a manageable level. This led
to flooding, landslides and, unfortunately, the deaths of several hundred people downstream.
Overall it is estimated that the frequency of major flooding can be reduced from once
every decade, to just once every century.
So how was it built?
Building on this scale and across a massive river is no easy feat and it took 17 years. So
in order to even begin construction, engineers had to overcome two challenges. They needed to
block the Yangtze's flow upstream and at the same time they had to make sure that enough water could
still pass through. Since the river's continuous flow is vital for the cities downstream.
So, during construction, stone enclosures were placed upstream. This enabled workers
to lay the first part of the foundations on dry land. To create a perfect balance,
engineers made use of cofferdams and directed the Yangtze's flow around them.
Once the concrete structure was completed, they started installing the first turbines. After
that the cofferdams were blown up and the water reached the dam’s turbines for the first time.
In total the dam cost over $30 billion dollars.
Other than power generation and flood control,
another benefit of this megaproject is that it’s easier now to navigate the Yangtze upstream.
With its winding turns and unpredictable water levels, the river is known to be a
dangerous waterway to traverse (4). So, the creation of the Three Gorges Dam helps
to increase water levels upstream allowing for the safe passage of even larger ships.
To get massive ships across the dam, they use a series of ship locks and a very special feature:
The largest ship lift in the world.
This machine is capable of carrying
vessels weighing as much as 3000 tonnes over an elevation of 110
meters (16). Compared to the locks which normally take up to four hours, the
lift does the trick in only 30 minutes.
The construction of such a project requires a high
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with the biggest ship lift in the world.
Ever since the construction of these passageways,
the freight capacity of the Yangtze has increased by as much as six times. Meanwhile, the cost
of shipping has continued to decrease proving the project’s importance as a catalyst
for economic growth in the region.
Just recently, it was also announced that
more than 23,000 individual vessels passed through the Three Gorges just in the first
half of 2023. This marks a 10% increase from the same period last year (17).
Because it holds so many records, another side effect is that the structure
became a tourist attraction. As much as 10 million tourists over the past five
years (8). It even has its own viewing deck and exhibition hall where
tourists can get a brief glimpse of the project’s construction (9). So far, all this sounds great. But of course
there are many challenges and problems when it comes to building a structure of this
size and with such a large impact.
So what are these problems?
Even before construction began, it was already estimated by the developers that
thousands of cities, towns, and villages would either be partially or completely submerged
by the reservoir. Because of this, around 1.4 million people were forced to relocate to higher
ground. (13) Although the government provided compensation and assistance for relocation,
there were reports of poor-quality housing, lack of essential amenities, and inadequate
infrastructure in the new resettlement areas.
People had to leave behind their homes,
farmlands and their communities.
Another point to pay attention to is its
tremendous and permanent effect on the environment and wildlife surrounding the Yangtze
River. For example, ever since its construction, landslides have become a common occurrence
within the area. These landslides have already cost millions of dollars in damages (10) (11).
Also, the Yangtze River is known for its richness in species and biodiversity. But some of these
plants and animal species are now endangered. For example, the dam could be responsible
for the extinction of the Chinese river dolphin and the Chinese paddlefish, though
shipping certainly also plays a role here.
Critics have also questioned the capabilities
of the Three Gorges in preventing major floods with the most recent 2020 monsoon rainfalls.
The Yangtze saw some of the highest average precipitation in almost 60 years as the
heavy rains caused the river to overflow. More than 150 people were reported
to have died or gone missing during this event prompting a closer look
at the efficacy of the project in preventing such disasters (13).
And then there’s one more thing:
At first sight this looks like a calm lake in
a beautiful landscape. However, something sets this reservoir apart from any ordinary lake – its
existence is owed solely to the colossal dam.
Should the unthinkable happen, and the
dam were to break, the massive amounts of water would roar downstream, sweeping away
everything in their path. The consequences would be unimaginable – communities devastated,
lives lost, and a landscape forever changed.
Such an event would put the lives of more
than 400 million people living around the Yangtze River in danger. It would also threaten
the very existence of major cities downstream such as Wuhan and Shanghai and would prove
catastrophic for the Chinese economy.
Of course, the engineers are aware of this and the
dam is regularly inspected, but there still was concern when these satellite images showed up.
They show a slightly ‘distorted’ shape of the Three Gorges dam, which is why concerns
over its structural integrity were put into question. One German-Chinese hydrologist was
even quoted in the media stating that “cracks and substandard concrete” were discovered.
However, Chinese media were quick to dismiss the rumors saying that the viral images
were the result of algorithm errors in Google Maps (22). They also explained that the
structure does in fact deform slightly but not as much as the images have shown (22).
The situation is not simple. Nevertheless, it should be expected that its safety is a
top priority, especially for the developers.
To sum it up, it becomes evident that
the role of this dam extends far beyond its engineering brilliance. It has
to hold back the forces of nature as long as the reservoir behind it exists.
So what does the future hold for this project?
Although the theoretical maximum capacity of
the Power Plant is 22.5 GW, in reality, only 45% of this is actually generated by the facility.
Because of the Yangtze’s seasonal changes, the force of water flowing through the Three Gorges’
turbines can vary depending on the time of year.
By comparison, the Itaipu Dam located on
the border between Brazil and Paraguay, sometimes actually outperforms the Three
Gorges. The site of the plant used to be home to the world’s largest waterfall by
volume (20), which was subsequently submerged following the construction of the reservoir.
Because of this, the flow of water across the Itaipu is much more consistent and stronger.
To further increase the Three Gorges’ efficiency, there have been studies conducted on the
potential use of artificial intelligence to optimize the facility’s energy generation
capabilities (18) (19). Using historical data on the Yangtze’s flow, researchers
have been able to make use of algorithms to predict the power generation of the dam in
any given season (19). They have concluded that these models can be used by its operators
to increase efficiency in the long term.
Another future plan to improve the Three
Gorges is the construction of portage railways on both sides of the river (21). Through
this system, cargo from ships would be transferred onto awaiting trains as they are carried to the
other side of the dam and loaded onto another vessel. In addition to the site’s existing ship
locks and lift, this future railway would make the transit of cargo across the dam even easier.
With all these additions, the Three Gorges Dam continues to stand as a symbol of human
engineering. But what do you think about it? Do you think its benefits can outweigh
its negative consequences? Let us know down below. As always, thank you for watching,
and we will see you in the next video!
