Standing on the bank of the Mekong River, Tran Van Cung can see his rice farm wash away before his very eyes. The paddy’s edge is crumbling into the delta.
Just 15 years ago, Southeast Asia’s longest river carried some 143 million tonnes of sediment – as heavy as about 430 Empire State Buildings – through to the Mekong River Delta every year, dumping nutrients along riverbanks essential to keeping tens of thousands of farms like Cung’s intact and productive.
But as Chinese-built hydroelectric dams have mushroomed upriver, much of that sediment is being blocked, an analysis of satellite data by Germany-based aquatic remote sensing company EOMAP and Reuters shows. The analysis reinforces an estimate by the Mekong River Commission, set up in 1995 by countries bordering the river, that in 2020 only about a third of those river-borne soils would reach the Vietnamese floodplains, and at the current rate of decline, less than five million tonnes of sediment will be reaching the delta each year by 2040.