Starving the Mekong by Reuters

Environmentalists have warned for decades that Mekong River dams were threatening the natural flow of sediment – a centuries-old system delivering nutrient-rich mud down the 5,000-km waterway to the fisheries and farms of the Mekong Delta. While an intergovernmental river commission was projecting steep sediment declines to come, residents were saying the fish were already getting smaller, the land less fertile, and the riverbanks crumbling away. No one had yet shown in data, however, that dams in China and Laos were indeed holding back soil. And China for years denied that the dams had any real impact.

‘Starving the Mekong’ offers exclusive and ground-breaking evidence to demonstrate that the dams are not only trapping sediment – but by staggering amounts.

Examining thousands of satellite images spanning three decades, Reuters analyzed sediment levels around four major dams on the Mekong. The analysis, done in cooperation with Germany-based aquatic remote sensing company EOMAP, calculated “turbidity” readings from the images – measuring the amount of light scattered by solid particles suspended in water – as a proxy for sediment levels.

Each of the four dams were shown to be reducing sediment flows by an average of 81%, the analysis shows – offering unprecedented evidence to support years of theories, estimates and anecdotes.