DAM COLLAPSE IN CHINA STIRS TALK OF ‘BLACK SWAN’ DISASTER

The dam at a small reservoir in China’s Guangxi region gave way last month after days of heavy rain in a collapse that could be a harbinger of sterner tests for many of the country’s 94,000 aging dams as the weather gets more extreme, Ryan Woo reported for Reuters on Wednesday, July 22, 2020.

Located in Yangshuo county and famed for its otherworldly karst landscape, the dam collapsed at around midday on June 7, inundating roads, orchards and fields in Shazixi village, residents told Reuters.“I’ve never seen such flooding,” said villager Luo Qiyuan, 81, who helped build the dam decades ago. “The water levels were never so high in previous years, and the dam had never collapsed.”

Completed in 1965, the dam, made of compacted earth, was designed to hold 195,000 cubic metres of water, enough to fill 78 Olympic-size swimming pools and meet the irrigation needs of Shazixi’s farmers. On a visit to the reservoir in mid-July, Reuters found the length of the dam, of about 100 metres, had largely vanished. It was reinforced 25 years ago.

The water went over the dam, which then collapsed, said a member of a survey crew at the reservoir, declining to be identified as he was not authorized to speak to media. Shazixi residents said there were no deaths. But the collapse, which was not reported by domestic media, suggests big storms might be enough to overwhelm reservoirs, especially if the design is inferior and maintenance has been patchy. That raises the prospect of disaster in river valleys and flood plains that are much more densely populated than they were when the dams were built.

Environmental groups say climate change is bringing heavier and more frequent rain. Massive flooding could trigger unforeseen “black swan” events, the government says, with extreme consequences. Thousands of dams were built in the 1950s and 1960s in a rush led by Mao Zedong to fend off drought in a largely agrarian China but in 2006, the Ministry of Water Resources admitted that between 1954 and 2005, dikes had collapsed at 3,486 reservoirs due to sub-standard quality and poor management.