By 2050, more than half the global population would live downstream from tens of thousands of large dams near or past their intended lifespan, according to a UN report released on Friday.
Most of the world’s nearly 59,000 big dams — constructed between 1930 and 1970 — were designed to last 50 to 100 years, according to research from the UN University Institute for Water, Environment and Health.
“This is an emerging global risk that we are not yet paying attention to,” coauthor and institute director Vladimir Smakhtin said.
Photo: Reuters
“In terms of dams at risk, the number is growing year by year, decade by decade,” he said.
A well-designed, constructed and maintained dam can easily remain functional for a century, but many of the world’s major dams fail on one or more of these criteria.
Dozens have suffered major damage or outright collapse over the past two decades in Afghanistan, Brazil, India, the US and other countries, and the number of such failures could increase, the report said.
Compounding the risk in ways that have yet to be fully measured is global warming.
“Because of climate change, extreme rainfall and flooding events are becoming more frequent,” said lead author Duminda Perera, a researcher at the University of Ottawa and McMaster University.
This not only increases the risk of reservoirs overflowing, but also accelerates the buildup of sediment, which affects dam safety, reduces water storage capacity, and lowers energy production in hydroelectric dams.
In February 2017, the spillways of California’s Oroville Dam — the tallest in the US — were damaged during heavy rainfall, prompting the emergency evacuation of more than 180,000 people downstream.
In 2019, record flooding sparked concern that Mosul Dam, Iraq’s largest, could fail.
Aging dams not only pose a greater risk to downstream populations, but also become less efficient at generating electricity, and far more expensive to maintain. Because the number of large dams under construction or planned has fallen sharply since the 1960s and 1970s, these problems would multiply in coming years, the report showed.
“There won’t be another dam-building revolution, so the average age of dams is getting older,” Perera said. “Due to new energy sources coming online — solar, wind — a lot of planned hydroelectric dams will probably not ever be built.”
A global fleet of nearly 60,000 aging dams also highlights the challenge of dismantling — or “decommissioning” — those that are no longer safe or functional.
Several dozen have been torn down in the US, but all of them small, Smakhtin said.
More than 90 percent of large dams — at least 15m from foundation to crest, or holding back no less than 3 million cubic meters of water — are located in only two dozen countries.
China alone is home to 40 percent of them, with another 15 percent in India, Japan and Korea combined. More than half will be older than 50 within a few years.
Another 16 percent of the world’s dams are in the US, more than 85 percent of them already operating at or past their life expectancy. It would cost about US$64 billion to refurbish them, according to one estimate.
In India, 64 big dams will be at least 150 years old by 2050.
In North America and Asia, there are about 2,300 operational dams at least 100 years old. Worldwide, there is about 7,500 cubic kilometers of water — enough to submerge most of Canada by a meter — stored behind large dams.
Republican US lawmakers on Friday criticized US President Joe Biden’s administration after sanctioned Chinese telecoms equipment giant Huawei unveiled a laptop this week powered by an Intel artificial intelligence (AI) chip. The US placed Huawei on a trade restriction list in 2019 for contravening Iran sanctions, part of a broader effort to hobble Beijing’s technological advances. Placement on the list means the company’s suppliers have to seek a special, difficult-to-obtain license before shipping to it. One such license, issued by then-US president Donald Trump’s administration, has allowed Intel to ship central processors to Huawei for use in laptops since 2020. China hardliners
A top Vietnamese property tycoon was on Thursday sentenced to death in one of the biggest corruption cases in history, with an estimated US$27 billion in damages. A panel of three hand-picked jurors and two judges rejected all defense arguments by Truong My Lan, chair of major developer Van Thinh Phat, who was found guilty of swindling cash from Saigon Commercial Bank (SCB) over a decade. “The defendant’s actions ... eroded people’s trust in the leadership of the [Communist] Party and state,” read the verdict at the trial in Ho Chi Minh City. After the five-week trial, 85 others were also sentenced on
Conjoined twins Lori and George Schappell, who pursued separate careers, interests and relationships during lives that defied medical expectations, died this month in Pennsylvania, funeral home officials said. They were 62. The twins, listed by Guinness World Records as the oldest living conjoined twins, died on April 7 at the Hospital of the University of Pennsylvania, obituaries posted by Leibensperger Funeral Homes of Hamburg said. The cause of death was not detailed. “When we were born, the doctors didn’t think we’d make 30, but we proved them wrong,” Lori said in an interview when they turned 50, the Philadelphia Inquirer reported. The
RAMPAGE: A Palestinian man was left dead after dozens of Israeli settlers searching for a missing 14-year-old boy stormed a village in the Israeli-occupied West Bank US President Joe Biden on Friday said he expected Iran to attack Israel “sooner, rather than later” and warned Tehran not to proceed. Asked by reporters about his message to Iran, Biden simply said: “Don’t,” underscoring Washington’s commitment to defend Israel. “We are devoted to the defense of Israel. We will support Israel. We will help defend Israel and Iran will not succeed,” he said. Biden said he would not divulge secure information, but said his expectation was that an attack could come “sooner, rather than later.” Israel braced on Friday for an attack by Iran or its proxies as warnings grew of