Hugely controversial, for almost 90 years from its inception to its opening, the Three Gorges Dam is a wonder of modern technology and engineering. The big concrete structure has converted the dangerous Yangtze River situated in Chongqing municipality, into a navigable trade route from Shanghai to Chongqing.
Location: Sandouping Village, Yichang County, Hubei Province.
Project Dimensions: 2.31 km in length, with the crest elevation at 185 m and a maximum height of 181 m.
Project Completed: 2009
A monumental engineering achievement – bridging two centuries at the cost of irreversible impact on nature and society.
From an early design, Sun Yat-sen, the founding father of modern China, saw the dam as a part of his economic development plan for China in 1919. For a country eager to cement its place as a world leader, the three gorges dam is a tool to boost energy security while simultaneously reducing coal-based carbon emission to be viewed as a developed nation. Yat-sen envisioned to use the vast hydropower resources of the river to produce electricity to build factories that make artificial fertilizer, which would make China achieve the leap in agricultural productivity to accommodate their growing population’s needs.
The site chosen for construction can accommodate the lake upstream of the dam and The granite with 100 MPa of compressive quality, frames a decent establishment bed for the dam. Additionally, there are no major troublesome geologic structures in the region around the site, while the local seismic activities are little in power, low in recurrence. Also, the existence of the small islet of Zhongbao near the side bank of the river was favorable for the diversion project. At last in 1992, with Pan Jiazheng as the ‘chief architect’ the construction for the 60-story high concrete gravity dam, began in 1994.
It has two power plants, navigation facilities, and a dam with three sections: the spillway dam – to release some pressure off the foundation, the intake dam, and the non-overflow dam. Additionally, 22 sluiceways each 8 meters wide with sputtering tips are constructed. The water is first directed into the dams and then down the concrete tubes into the 33 enormous turbines to spin and activate the 34 generators thus generating electricity. Fun Fact: When the dam is running at its full capacity it produces over 4 times the energy of the most powerful nuclear power station in the world yet only generates 1.25% of China’s power supply.
Construction Timeline
1993-1997: A rotation system was implemented, therefore the right side of the beach was closed with cofferdams, and space on the left side of the beach was arranged for the passage of vessels.
1998-2003: The dam and the powerplant were constructed on the left side of the beach. Sluiceways and Spillways were constructed in the middle of the dam. The turbine and generators were slowly added in stages and the cofferdams were dismantled with explosives to let the water reach the turbines.
2003-2009: The third and final phase was the construction of the right side of the dam and placement of all generators.
Construction Process
The main work quantities to be done in the construction for principal structures and diversion works were as follows:
Earth-and-rock excavation:
The construction pit for erecting the dam was dug to a depth of 260 ft. Numerous holes were drilled into the ground and filled with pressurized grout, to help protect the dam from being uplifted by preventing water from seeping underneath the structure.
Earth-and-rock embankment:
870,000 sq ft of concrete walls were sunk below the transverse cofferdams.
Concrete and Rebar placing:
As the dam progresses, six tower cranes specially fitted with jacking systems raise the conveyors. In addition to their lifting capacity, the tower cranes have swinging telescopic conveyors that are designed to pour concrete at the impressive rate of more than 600 cubic yards per hour.
Metalworks:
The double-way, five-step flight ship lock was carved from granite and lined with concrete, placed on the river’s left side bank.
Installation of hydro turbine generator:
Turbines and generators were installed that operate in the two hydropower stations on each bank.
Is Three Gorges Dam A Sustainable Approach Towards The Development OF China’s Economy?
The scale of the Three Gorges Dam has led to inevitable social impacts. However, its contribution to China’s industrialization and economy cannot be questioned.
- The dam’s reservoir acts as a buffer and can lessen the risk of floods, by storing waters but has blocked the migration of fish and has driven the Chinese River Dolphin to extinction, causing enormous ramification on the ecosystem. The reservoir has increased water availability for irrigation, industrial use, and human consumption, and the hydropower it generates aids in China’s electricity consumption.
- The dam destroyed religious and archeological sites, farmland, and homes and contaminated the water as all the infrastructure was submerged underwater. The relocation of 1.3 million people and upward migration of farmers also led to deforestation that led to soil erosion.
- It has helped in the reduction of greenhouse gases that contribute to global warming but has contributed severely to weather changes around the region like a decrease in the rainfall around the region and the temperature on the mountains, increasing the frequency of landslides and the reservoir has triggered earthquakes all over the world. Fun Fact: The Three Gorges Dam sits on two major earthquake fault lines.
- The dam has accumulated 10 million tons of rubbish over the years which can cause the turbines to stop working once it reaches them and it could cause huge structural damage. Hence, the Chinese government developed a Garbage-lapping “tongue”, a device that can consume 300 cubic meters of rubbish per hour. Fun Fact: China will spend about 40 billion yuan to build at least 150 sewage treatment plants and 170 urban garbage disposal plants due to the dam.
When the dam filled up its reservoir it held 10 trillion gallons of water it moved the earth’s mass further from the axis hence, slowing down the earth’s rotation, which makes one day now 60 nanoseconds longer. The dam has moved the north and south pole by 0.8 inches each and is said to have triggered multiple earthquakes over the years to move the earth’s mass closer to the axis. Fun fact: Which weighs 83.4 trillion pounds a small portion of the 13 septillion pounds earth weighs but is enough shifting mass to affect.
On July 19th, 2020, China issued a Yellow Alert for rainstorms, evacuating 40,000 locals as the dam could be at risk of collapsing. Although Chinese authorities claim the dam is structurally strong, a hydrologist Wang Wei Lau – says the dam is constructed of materials which are below standards and hence, can’t provide flood protection. Shortly after filling up the reservoir 80 hairline cracks appeared on the structure despite all 163,000 concrete units passing quality control tests. In 1998 after a flood, the quality control of the building was assessed and it was concluded that the steel bar welding of the dam didn’t meet the standards.
In 2009, the dam was a straight line but in 2018, it had a slight curve – Estate experts revealed the dam had moved a few millimeters but within the normal safety range. Wang said the dam has moved due to its flawed design. He claimed the dam is composed of dozens of independent concrete blocks that are not connected to the bedrock below and hence could collapse, killing 400 million as the Yangtze River flows through big cities like Shanghai and Wuhan. Fun fact: First claims were made that the dam could withhold the worst floods for 10,000 years which was later changed to 1,000 years and 100 years a year after.
Three Gorges Dam – a cosmic sublimity inspired by the possibility of planetary destruction. Looking down through the still surface of the lake to the submerged world below gives us a premonition of that future. Would the dam turn out to be a magnificent human achievement that brought clean energy to China or a bloated ecological disaster that caused great hardships to millions over the years is still unknown!
