08/02/21

Ageing dams are ‘ticking time bombs’

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The Mullaperiyar dam, which was built in the 20th century, is included in the UN University – Institute for Water, Environment and Health list of large dams that should be decommissioned. Copyright:马拉雅拉姆语维基百科的Bipinkdas,(SA 3.0的CC)

速度阅读

  • 印度拥有209个以上的水坝,超过了寿命
  • Over 40 per cent of the world’s large dams are in China
  • 1975年,中国的大坝倒塌夺走了200,000多人的生命

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[NEW DELHI] Perched high up in the Western Ghats, adjacent to Kerala’s famed Periyar wildlife sanctuary, is a 126-year-old dam that has dangerously outlived the 50 years of life intended for it by colonial British engineers.

N.K. Premachandran, a member of parliament from Kerala, describes the 53.6 metre-high Mullaperiyar dam on the Periyar river as “a ticking timebomb waiting to explode, not only because of its antiquity but also because it is located on an acknowledged seismic zone”.

“As Kerala’swater资源部长(从2006年到2011年),我委托有关大坝安全的研究Indian Institute of Technology (IIT)at Roorkee, which specialises in dams and irrigation, and IIT-Delhi. Both institutes had deemed Mullaperiyar fit to be decommissioned but the issue got bogged down in political wrangling and litigation in the Supreme Court,” Premachandran tellsscidev.net。

mullaperiyar大坝的横截面。图片来源:Captain(CC BY-SA 3.0).

Premachandran is happy to see Mullaperiyar listed among the world’s big dams that need to be decommissioned in areportreleased 22 January by the联合国大学 - 水,环境与健康研究所(UNU-INWEH)beplay足球体育的微博。“Let’s hope the UN study will encourage authorities, including the Supreme Court, to decide early to decommission this dam that threatens the lives of millions,” he adds.

“Dams as a means of water security are passé, as pointed out by the UN-sponsored study,”

C.P.拉金德兰(Rajendran),国家高级研究所

Duminda Perera, an author of the study and an expert on water resources and water-relateddisasters,说:“我们选择了Mullaperiyar大坝作为在结构性缺陷,政治压力和环境问题的地震活跃地区老化但仍在运转的大坝的一个很好的例子,如已出版的文献所记录的那样。”beplay足球体育的微博

Opposition to decommissioning

Decommissioning Mullaperiyar is strongly opposed by Tamil Nadu state, which inherited a租赁协议在前王子国家(现为喀拉拉邦)和英国人之间government。The lease allows Tamil Nadu to operate the dam and divert 640 million cubic metres of water annually for irrigation and18beplay generation through a tunnel bored into the Western Ghat mountains that form a wall between the two states.

But Mullaperiyar ticks all the boxes that the UNU-INWEH study identifies for decommissioning — public safety, growing maintenance costs, reservoir sedimentation andenvironmentalrestoration. Large dams, even if structurally sound, are regarded as ‘high hazard’ infrastructure because of the potential for massive loss of human lives, livelihoods and destruction in the event of failure, the study said.

佩雷拉告诉佩雷拉说:“我们的研究在全球范围内讨论了大坝衰老问题,使该主题浮出水面,并希望引起国家层面决策者的注意。”SciDev.Net。“在对大坝及其与经济和社会的联系进行仔细而深入的分析之后,应采取退役决定。”

“有许多强有力的拥护者来增加与安全有关的大坝投资。例如,世界银行在过去的几年中,印度的一项大坝康复改善计划投资了超过10亿美元,”佩雷拉说。

全球衰老的水坝

China, the US and India top the list of countries with a significant number of large dams. China alone hosts 40 per cent of the of the world’s large dams (numbering 23,841), their average age being 45 years. According to官方记录,印度有209个水坝已有100多年的历史,当时设计实践和安全远低于当前规范。

非洲的大水坝比其他大陆少得多,尽管还有一些著名的建筑物,例如加纳的阿科索博大坝,赞比亚的卡里巴大坝和津巴布韦,以及埃及的阿斯旺大坝。该研究说,尽管非洲越来越依赖水电,但非洲大坝的平均年龄不到50岁。

Aswan Dam in Egypt. Image credit:Orlova-tpe(CC BY-SA 3.0).

Latin America’s large dams are also yet to face the widespread ageing seen in other regions, although the average age in some functional categories is close to 50 years. More than half of all large dams in South America are found in Brazil, with a handful over 50 years.

该研究列出了有据可查的病例,即50至100岁之间的大坝失败。其中包括Panjshir Valley大坝(阿富汗,2018年),Ivanovo大坝(保加利亚,2012年),Situ Gintung大坝(印度尼西亚,2009年)和Kantale Dam(Sri Lanka,1986年)。

Whether from excessive seepage, cracking, overtopping, or structural flaws, dam failures are frequently the result of poor design or construction, lack of maintenance, or operational mismanagement, the study said.

印度的专家列举了古吉拉特邦的Machchu II大坝的灾难性1979年失败,该大坝被委托后20年,是管理不善的一个例子。在大雨之后,大坝填充了其容量四倍,倒塌了,导致15,000多人死亡,并破坏了下游五公里的低洼工业小镇Morbi。

Machchu II水坝倒塌的数字是世界上最严重的大坝灾难,仅次于中国1975年的Banqiao大坝故障,据估计,亨南省240,000名居民的生命。中国从未发布过伤亡或损害的官方人物。

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Unrealised risks

C.P.Rajendran, a top地质学家at India’s国家高级研究所and member of an expert committee appointed by the Kerala government to study the stability of the Mullaperiyar dam, says that the “lower bound of life-expectancy being 50 years combined with siltation problems means that most of India’s dams are reaching the end of functional life”.

Additionally, says Rajendran, India and China have fast-forwarded their dam-building activities, ignoring the ecological and seismologicalvulnerabilityof the Himalayan regions, especially in the backdrop of climate change that accentuates glacier melting and the flood situations. “Dams as a means of water security are passé, as pointed out by the UN-sponsored study.”

The dangers of building dams in ecologically sensitive areas were highlighted on Sunday (7 February) when a Himalayan glacier fell into the Dhauli Ganga river in the Uttarakhand region. It triggered huge floods, swept away a small dam and damaged a bigger one downstream leaving a trail of destruction. More than 100 people are missing and feared dead after being caught in the torrent, including more than 50 workers of the smaller dam.

For the Mullaperiyar, IIT- Roorkee estimated in its report to Premachandran that it would fail if an earthquake of 6.5 magnitude occurs in a radius of 16 kilometres when the water level in the dam is at 41 meters. According to the UN study, such an event would endanger the lives of 3.5 million people in Kerala.

“By 2050, most people on Earth will live downstream of tens of thousands of large dams built in the 20th century, many of them already operating at or beyond their design life,” the study said.

This piece was produced by SciDev.Net’s Asia & Pacific desk.