Practically 100,000 dams in China

The annual floods of the Yangtze River (the Yangtze River) is among the the reason why China determined to construct the Three Gorges Dam – the biggest dam within the nation’s historical past – so as to add to the system of hundreds of dams. accessible on the mainland.

The thought right here is that by storing water and releasing it slowly, they are going to management the circulation of water and stop a catastrophe just like the historic 1931 flood that killed hundreds of thousands in cities. alongside the Yangtze River; or the floods of 1998 that left hundreds of thousands homeless.

  Nearly 100,000 dams in China - time bombs in the era of increasingly extreme climate change - Photo 1.

Three Gorges Dam – the biggest hydroelectric dam in Chinese language historical past

“The Three Gorges Dam is a software for flood management,” – Deputy Minister of Water Assets speaks after finishing this venture.

China has about 98,000 dams – most of that are small in scale and constructed earlier than 1970. In addition to flood management, these dams play an essential position in hydroelectricity and offering water for the inhabitants. . Nonetheless, in recent times, floods are occurring extra actually because unusually heavy rains are inflicting numerous concern. The query is: The right way to management almost 100,000 dams within the period of local weather change, when excessive rains are threatening the lives of surrounding communities?

  Nearly 100,000 dams in China - time bombs in the era of increasingly extreme climate change - Photo 2.

In July 2021, the Yihetan Dam – a large dam in central China’s Henan province appeared cracks and “severely broken” after torrential rains. Two different dams within the northern area of Inside Mongolia additionally ruptured and collapsed as a result of the water rose too excessive, affecting 16,000 folks. Even the Three Gorges Dam – the nation’s largest dam – is inflicting concern after heavy rains final yr, which raised water ranges at an alarming fee.

“Local weather change may very well be getting stronger than anticipated, which is what we did not take into consideration when designing this dam,” he mentioned. – Wen Wang, professor of hydrology from Ho Hai College (Nanjing) commented. Professor additionally mentioned that this must be a problem that must be prioritized by engineers, though essentially the most troublesome half lies in predicting rainfall within the close to future.

  Nearly 100,000 dams in China - time bombs in the era of increasingly extreme climate change - Photo 3.

The historic flood in Zhengzhou final July

Period of utmost local weather change

It is exhausting to say that any excessive climate occasions are tied to world warming. Nonetheless, a report from the IPCC (Intergovernmental Panel on Local weather Change) launched on August 9, the rains and floods with the depth of “10 years as soon as” are occurring an increasing number of. In East Asia, the IPCC predicts that within the coming years rain will fall extra ceaselessly, and extra closely.

Zhengzhou metropolis – the capital of Henan province is an instance. On July 20, Zhengzhou suffered a rain that poured down your entire yr’s water in simply sooner or later. That rain prompted extraordinarily extreme flooding, killing greater than 300 folks, together with many passengers trapped within the flooded subway.

  Nearly 100,000 dams in China - time bombs in the increasingly extreme climate change era - Photo 4.

Johnny Chan, a professor of meteorology from the College of Hong Kong, mentioned it was an unprecedented downpour within the metropolis’s historical past. However with the Earth warming, water evaporating sooner, it’ll quickly turn out to be commonplace.

Based on a report by the Nationwide Meteorological Heart beneath the China Meteorological Administration, the common temperature within the mainland this summer season has been above common in comparison with every other yr. In the meantime, 2020’s rainfall is the 4th most since 1951. Heavy rains trigger extreme flooding throughout southern, central and japanese China. In consequence, the quantity of water on the Tam Hiep dam rose almost 2m greater than the flood warning degree.

Controlling local weather change

The Xinfa Dam in Inside Mongolia – one of many dams to break down in 2021 – was “very effectively constructed and ready for flooding”, mentioned Mohammad Heiderzahad, an affiliate professor of civil engineering at Brunel College in London. ), additionally a hydroelectric dam engineer. He mentioned the dam collapsed too shortly regardless of having two overflow weirs and an emergency blow-off, which permit secure withdrawal of water when the dam is at risk of overflowing.

  Nearly 100,000 dams in China - slow-explosive bombs in an era of increasingly extreme climate change - Photo 5.

The trigger is claimed to be as a result of the rainfall is so horrible that it exceeds the utmost flood index PMF (Possible Most Flood) for which the dam is designed. PMF is an idea that refers back to the most flood storage capability {that a} dam can carry.

“If such rains turn out to be the ‘new regular’, the bigger the dams, the extra possible they’re to place residents in danger,” he mentioned. – Heiderzahad commented. He additionally instructed that an extra emergency blowdown line is required at present dams to mitigate the danger.

Xinfa Dam collapse

  Nearly 100,000 dams in China - slow-explosive bombs in an era of increasingly extreme climate change - Photo 7.

In reality, issues do not simply cease at theoretical dangers anymore. In 2020, Chinese language authorities have been pressured to explode a dam, earlier than the quantity of water there reached irreparable ranges.

Nonetheless, Professor Wen Wang from Ho Hai College disagrees. He would not suppose the dam’s dimension issues, however slightly a mix of reservoirs and water management strategies. When the water degree can’t be handled, the dam must launch the reservoir as quickly as potential – this relies lots on the power to foretell the climate.

As on this yr, the Three Gorges Dam has discharged 90% of the water within the lake from the start of June to welcome the start of the flood season. But when many dams must launch water, it dangers exposing areas downstream to flooding, particularly when accompanied by heavy rain.

“We have now to maintain all the things in stability, although. If the reservoirs are usually not empty sufficient to arrange for the flood season, the dam may very well be destroyed with much more dire penalties.”

Supply: QZ


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