TIDAL wetlands on the Yangtze delta near Shanghai in China are in danger of disappearing because of sediment trapped in the Three Gorges dam. The amount of sediment coming downstream has more than halved since the dam’s construction. As a result the tidal wetlands around Shanghai have been eroding rapidly, damaging coastal ecological systems and limiting Shanghai’s ability to expand.
Shi-lun Lang and his colleagues from East China Normal University in Shanghai studied sediment discharge data collected between 1951 and 2004. They found that sediment carried in the Yangtze river has dramatically fallen since construction of the Three Gorges dam…
