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6park.comChina's Three Gorges Dam is one of the largest ever created. Was it worth it? 6park.comThe Three Gorges Dam was designed to tame China's longest river. But this summer's record rains reveal its limited ability to control floods. 6park.com 6park.comWritten by:Nectar Gan, CNN
Published 1st August 2020
6park.comThree Gorges Dam is the largest hydropower project ever built. 6park.comWhen construction began in 1994, it was designed not only to generate electricity to propel China's breakneck economic growth, but also to tame China's longest river, shield millions of people from fatal floods and, as a symbol of technological prowess, become a searing point of national pride. 6park.comBut it hasn't quite worked out that way. 6park.comFor a start, the whole project cost 200 billion yuan ($28.6 billion), took nearly two decades to build, and required uprooting more than a million people along the Yangtze River. And while the government promised the dam would be able to protect communities around its immediate downstream against a "once in a century flood," its efficacy has frequently been questioned. 6park.comThose doubts recently resurfaced, as the Yangtze basin saw its heaviest average rainfall in nearly 60 years since June, causing the river and its many tributaries to overflow. 6park.comMore than 158 people have died or gone missing, 3.67 million residents have been displaced and 54.8 million people have been affected, causing a devastating 144 billion yuan ($20.5 billion) in economic losses. 6park.comDespite the havoc, Chinese authorities claim the Three Gorges Dam has succeeded in playing a "crucial role" in intercepting floodwaters. The dam's operator, China Three Gorges Corporation, told China's state news agency Xinhua that the dam has intercepted 18.2 billion cubic meters of potential floodwater. A water resources ministry official told state-run newspaper China Youth Daily that the dam "effectively reduced the speed and extent of water level rises" on the middle and lower reaches of the Yangtze. 6park.comBut with multiple gauging stations monitoring river flows in the Yangtze basin seeing record-high water levels this summer, some geologists say the limited role of the Three Gorges Dam in flood control has been laid bare. 6park.com 6park.comFootage of the Three Gorges Dam shot in July 2020. Credit: Reuters 6park.com'A tea cup for a big tub of water'
6park.comThe Three Gorges Dam is an awe-inspiring structure. 6park.comFirstly, it is one of the few man-made structures on Earth that's visible to the naked eye from space, according to NASA. Completed in 2006, the body of the dam is immense. It is 181 meters (607 feet) tall and spans 2,335 meters (1.45 miles) across the Yangtze just before the deep, narrow valley gives way to plains. 6park.comThen there's its accompanying hydropower plant, which was completed in 2012 and has a generating capacity of 22,500 megawatts, or more than three times the capacity of the Grand Coulee Dam, the largest in the United States. 6park.comBut according to the Chinese government's 1992 proposal, the top reason for building the dam wasn't power generation, but to prevent flooding. 6park.com6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com 6park.com1/22 6park.comWorkers hold up a layout plan of the Three Gorges Dam project by the Yangtze river in Hubei province in September 1995. Scroll through the gallery for images of the Three Gorges Dam, through the years. Credit: Chip HIRES/Gamma-Rapho/Getty Images 6park.comHere's how it works: the enormous dam is situated on an upstream section of the Yangtze and helps prevent flooding downstream by trapping rainwater in a huge reservoir, and then controlling the release of that water through its sluice gates. The 660 kilometer (410 mile) reservoir winds upstream through the narrow valleys of the Three Gorges -- a series of steep canyons known for their imposing beauty and once treacherous currents -- to Chongqing, a sprawling municipality of 30.5 million people in western China. 6park.comDuring the dry season, October to May, the reservoir's water level is kept at a maximum of 175 meters (574 feet) to optimize electricity generation at the adjoining hydropower plant. Before the summer rains arrive in June, it's gradually lowered to 145 meters (475 feet) to make room for the incoming floodwaters. 6park.comThe lowering of water levels creates 22 billion cubic meters of storage space -- enough to contain nearly 9 million Olympic-size swimming pools of water. But that's nothing compared with the sheer volume of floodwater that can flow into the dam during bad years, said Fan Xiao, a Chinese geologist and long-time critic of the dam. 6park.comDuring a "once-a-century flood" more than 244 billion cubic meters of water -- or about twice the volume of the Dead Sea -- can pass through the Three Gorges in two months, according to Fan's calculations. 6park.comThe storage capacity of the dam's reservoir can handle only about 9% of that amount, he added. 6park.com"It's like using a small cup to deal with a big tub of water. In terms of flood control, the cost of the dam has surely outweighed the gain." 6park.comBesides, the dam can only hold back the water for so long, as it has to make room for new rains -- and in flood season torrential downpours can come in quick succession. 6park.comLast month, three flood waves have already hit the Three Gorges. The dam has opened its sluice gates multiple times since late June to release water from its reservoir, drawing criticism on Chinese social media that this exacerbated the floods downstream. 6park.comThe company running the dam denied this, telling state-run tabloid the Global Times that it had helped to delay and stagger the floodwaters reaching downstream. 6park.comBut Poyang Lake, in Jiangxi province, still swelled to its highest level in history -- surpassing the previous record set by catastrophic floods in 1998, which killed more than 3,000 people. Other places downstream also broke historical records.
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