IT WAS probably the world’s biggest washout. And it helped engineers clean out the world’s muddiest river.
On 15 July, operators announced they had shifted some 6 million tonnes of sediment from the bottom of the Xiaolangdi reservoir in China by partially emptying it to expose the caked mud and then releasing a flood of water from a reservoir upstream. The deluge scoured out the reservoir, picking up sediment that it then carried to the sea 600 kilometres downstream.
The Yellow river carries more than 1 billion tonnes of sediment a year to the sea. But in recent years, as…
