Guwahati, March 9 -- Julian Leyland, University of Southampton

Sand underpins everything from skyscrapers to smartphones. Sharp sand (as opposed to rounded desert sand) is the key ingredient in concrete, while high-purity silica sand is essential for making the silicon chips that power our digital devices.

Yet the relentless extraction of this seemingly abundant resource is pushing river systems to the brink of collapse, displacing communities and fuelling a billion-dollar black market.

Despite its critical role in modern society and urban development, the environmental and social effects of sand mining remain largely hidden from public scrutiny. The UN's environment programme (Unep) warns that global sand consumption now exceeds 50 bi...