The closer to the delta, the fewer sediments in the river, the more precarious the situation for the people – the Vietnamese on the Mekong also feel this. In their country, the river flows into the South China Sea. This is where the ecological imbalance is greatest, and hardly any sediment can get through here. Upstream energy dams in Cambodia, Laos and China add to the attrition along the way. Much of the sandy material gets stuck in the dam structures. In other words, the sand that makes it through the dams is fished out of the water in Cambodia at the latest.
But why does nobody draw from the rich deposits in desert regions? The crux of the matter with sand is that sand is not just sand. The sand from the desert, for example, and also fine beach sand are not suitable for building material. They were worked by the wind. The sand that the companies need has to come out of the washing machine, so to speak: over decades, rivers give it the consistency that makes cement durable. So you often can’t see the sand in question, emphasizes Kiran Pereira. Enormous amounts would be used for land and beach fills, which could then stand for growth. But the impact of where the sand comes from is often ignored, “especially if it’s underwater.”
Vince Beiser has visited many mining areas, spoken to residents and university professors. One of these places, which is also “the largest sand pit in the world”, is Lake Poyang in the province of Jianxi in southeast China.