We need sand—and not just any sand. As rivers carry sediment, grains collide, creating craggy surfaces on the tiny rocks. Those rough surfaces translate into stability when river sand, gravel, and cement are combined to make concrete, the physical foundation of our modern world.
Though it’s the second-most sought-after resource next to water, sand is understudied and overused, in part because it seems like a limitless commodity, said Mette Bendixen, an assistant professor and physical geographer at McGill University in Montreal, Que. “We don’t have the full overview of where sand is being mined,” she said, “or how much is being taken.”
To that end, Chris Hackney, a Fellow and fluvial geomorphologist at Newcastle University in the United Kingdom, and his colleagues used satellite imagery to track sand mining in a short stretch of the Mekong River in Cambodia. He and his colleagues found that in this reach, the amount of sand that was removed increased annually, from about 24 million to 59 million metric tons per year between 2016 and 2020. This new estimate far exceeds previous ones collected before a recent uptick in urbanization.