The Mosul dam is crumbling. If it bursts, it would be a disaster on a biblical scale

The Mosul dam, in northern Iraq, holds back more than 12m cubic metres of water from the river Tigris. Completed by Saddam Hussein in 1986, and having been built on soluble gypsum, it was never the most stable of structures, requiring continuous grouting to maintain its integrity. But when Islamic State captured the dam in 2014, they ran off with all the grouting equipment. And even though the Kurdish peshmerga retook the dam some six weeks later, it is still close to the Isis front line, and the Kurds have been busy fighting, not grouting.

Last week the US embassy in Baghdad issued a warning that the risk of the dam failing is now “serious and unprecedented”. And if the dam was to burst, a 14 metre-high wall of water would be unleashed downstream that could drown over a million people and displace several million more. “The dam is in a very dangerous situation now,” said Dr Nasrat Adamo, the dam’s former chief engineer. “The coming floods in March and April will definitely raise the water to alarming levels. My feeling is the dam will fail sometime in the future.”