From the Hoover Dam in Arizona to the Inguri Dam in Georgia, many of the world’s most famous dams are in danger of collapsing, a disturbing new report warns.
Most of the 58,700 largest dams in the world have been built between the 1930s and 1970s, making them between the ages of 50 and 90.
However, most were only designed to last 50 to 100 years, meaning they are now reaching the end of their useful life.
Worryingly, if these dams were to collapse, they would release up to 8,300 cubic miles of water – enough to fill the Grand Canyon twice.
The researchers hope the findings will help policymakers make decisions about aging dams.
A new report warns that most of the 58,700 largest dams worldwide were built during this period and are at risk of collapse. Pictured is the Kariba Dam on the Zambezi River
THE GREATEST DAMS IN THE WORLD
1. Kariba Dam, Zimbabwe – 185 billion cubic meters
2. Bratsk Dam, Russia – 169.27 billion cubic meters
3. Akosombo Dam, Ghana – 144 billion cubic meters
4. Daniel Johnson Dam, Canada – 139.8 billion cubic meters
5. Guri Dam, Venezuela – 135 billion cubic meters
6. Aswan High Dam, Egypt – 132 billion cubic meters
7. WAC Bennett Dam, Canada – 74 billion cubic meters
8. Krasnoyarsk Dam, Russia – 73.3 billion cubic meters
9. Zeya Dam, Russia – 68.42 billion cubic meters
10. Robert Bourassa Dam, Canada – 61.7 billion cubic meters
In the study, researchers from the UN University Institute for Water, Environment and Health (UNU-INWEH) looked at the age and condition of the largest dams in the world.
They found that most of the 58,700 major dams worldwide were built between 1930 and 1870, with a lifespan of 50 to 100 years.
After this point, these dams would “likely start to show signs of aging,” the researchers said.
Duminda Perera, a senior researcher at UNU-INWEH, and lead author of the study, said: “ This problem of large dams aging is faced by a relatively small number of countries today – 93% of all major dams in the world are located in just 25 countries. .
Construction of large dams boomed in the mid-20th century, reaching a peak in the 1960s and 1970s, especially in Asia, Europe and North America, while the peak in Africa occurred in the 1980s. The number of newly constructed large dams subsequently decreased continuously and gradually. ‘
Worldwide, an estimated 7,000 to 8,300 cubic kilometers of water is stored behind large dams.
To put that in context, at the top of that estimate, it’s enough water to fill the Grand Canyon twice.
The team is alarmingly of the view that climate change can also accelerate the aging process.
Vladimir Smakhtin, director of UNU-INWEH and co-author of the study, said: “ This report aims to draw global attention to the insidious problem of aging water storage infrastructure and to spur international efforts to cope to this emerging, increasing water risk.
The problem of aging large dams is faced by a relatively small number of countries today – 93% of all major dams in the world are located in just 25 countries led by China and the US.
It is underlined that the increasing frequency and severity of floods and other extreme environmental factors can exceed the design limits of a dam and accelerate a dam’s aging process.
Decisions about decommissioning must therefore be taken in the context of a changing climate.
While thousands of dams were built between the 1930s and 1970s, dam construction has slowed in recent years as’ the best locations for such dams worldwide are gradually declining, as nearly 50% of the global river volume is already fragmented or regulated through drafts, “the report says.
The Hoover Dam in Arizona was built between 1931 and 1936 during the Great Depression
However, removing a dam is no easy task.
Most of the dams removed to date have been small, with only a few known cases of large dams being removed in the past decade.
Professor R. Allen Curry, associate professor of UNU-INWEH and co-author of the study, said: ‘Some case studies of aging and decommissioned large dams illustrate the complexity and length of the process often required to safely orchestrate dam removal. .
Even the removal of a small dam requires years (often decades) of continuous involvement from experts and the public, and lengthy regulatory overhauls. With the massive aging of dams well underway, it is important to develop a framework of protocols that guide and accelerate the process of dam removal. ‘
Overall, the researchers hope their findings will help policymakers decide what to do with aging dams.
The report added: ‘It is not an easy process, so learning lessons and sharing experiences of dam dismantling should be a common global goal.
“Lack of such knowledge and lack of reflection in relevant regional / national policies / practices can have a progressive and negative impact on the ability to manage water storage infrastructure properly as it ages.”