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Aging dams in India, the United States and other nations pose a growing threat: UN report | India News


NEW YORK: More than 1,000 large dams in India will be roughly 50 years old by 2025, and those aging structures around the world pose a growing threat, according to a UN report noting that by 2050, the majority of people on Earth will be living downstream of dozens. of thousands of dams built in the 20th century.
The report, titled ‘Aging Water Infrastructure: An Emerging Global Risk’ and compiled by the Canadian Institute of Water, Environment and Health at the United Nations University, says that most of the 58,700 large dams across the world world were built between 1930 and 1970 with a useful life of 50 to 100 years.
He said that at age 50, a large concrete dam “would probably begin to show signs of aging.”
Signs of aging include increasing cases of dam failures, rising costs of dam repair and maintenance, increased reservoir sedimentation, and loss of functionality and effectiveness of a dam – “strongly interconnected” manifestations, according to the report.
“By 2050, most people on Earth will be living downstream of tens of thousands of large dams built in the 20th century, many of which are already operating in their design life or beyond,” according to the analysis of the UN University.
The analysis includes case studies of dam decommissioning or aging from the US, France, Canada, India, Japan, Zambia and Zimbabwe.
According to the report, the world is unlikely to witness another great dam-building revolution like the mid-20th century, but the dams built then will inevitably show their age.
The report said 32,716 large dams (55 percent of the world total) are in just four Asian countries: China, India, Japan and South Korea, most of which will hit the 50-year threshold relatively soon.
The same is true of many large dams in Africa, South America and Eastern Europe, he said.
In India, there are more than 1,115 large dams that will be approximately 50 years old in 2025, more than 4,250 large dams in the country will be more than 50 years old in 2050 and 64 large dams will be more than 150 years old in 2050, he said.
The report says that approximately 3.5 million people are at risk if India’s Mullaperiyar Dam in Kerala, built more than 100 years ago, “fails.”
“The dam, in a seismically active area, shows significant structural faults and its management is a contentious issue between the states of Kerala and Tamil Nadu,” he said.
The report added that dams that are well designed, built and maintained can “easily” reach 100 years of service, but predicts an increase in “decommissioning”, a phenomenon that is picking up pace in the US and Europe. since economic and practical limitations prevent aging dams from being upgraded or if their original use is already obsolete.
In the United States, the average age of 90,580 dams is 56 years. More than 85 percent of US dams in 2020 were operating at or beyond their life expectancy and 75 percent of US dam failures occurred after 50 years of age. The estimated cost to renovate America’s dams is approximately $ 64 billion. About 1,275 dams were removed in 21 states in the United States in the last 30 years; 80 eliminated in 2017 alone, he said.
Worldwide, the enormous volume of water stored behind large dams is estimated at 7,000 to 8,300 cubic kilometers, enough to cover about 80 percent of Canada’s land mass under one meter of water.
Report co-author Vladimir Smakhtin, director of UNU-INWEH, said the report aims to draw global attention to the progressive problem of aging water storage infrastructure and stimulate international efforts to address this emerging and growing risk. of the water.
“It underlines the fact that the increasing frequency and severity of flooding and other extreme environmental events can exceed the design limits of a dam and accelerate the aging process of a dam. Therefore, decommissioning decisions must be taken in the context of a changing climate. ” Smakhtin said.
UNU-INWEH lead author and lead researcher Duminda Perera said that the problem of aging large dams today faces a relatively small number of countries: 93 percent of all large dams in the world are located in just 25 nations. .
“The construction of large dams emerged in the mid-20th century and peaked in the 1960s, especially in Asia, Europe and North America, while in Africa the peak occurred in the 1980s. The number of large dams Newly built dams thereafter continuously and progressively declined, ”he said.
The rate of construction of large dams has decreased dramatically in the last four decades and continues to decline in part because “the best locations for such dams around the world have been steadily declining, as nearly 50% of the world’s volume of rivers is already fragmented or regulated by dams, “says the report.
There is also great concern regarding the environmental and social impacts of dams, and large dams in particular, as well as emerging ideas and practices on alternative types of water storage, nature-based solutions and types of energy production beyond hydropower, he said. .
Public safety, increased maintenance costs, reservoir sedimentation, and restoration of a natural river ecosystem are among the reasons driving the dismantling of the dam, according to the report, adding that, in general, dismantling of the dam should be considered as important as the construction of the dam in the overall planning process in water storage infrastructure developments.

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