THE two ruddy-faced women are weighed down by their huge bundles of reeds. They have been out on the wetland, braving the winds from the South China Sea for two months, they say. They are hundreds of kilometres from their homes in Anhui province, cutting reeds for sale to a paper-maker. The money isn't great, but Anhui is a poor province and there is certainly no shortage of reeds out here.

Welcome to Chongming, the world's largest alluvial island, a 100-kilometre-long shifting mass of sand and mud in the delta of the Yangtze river. Chongming island has doubled in size since 1950, thanks to silt coming down the river from the deforested headwaters of the Yangtze. Now the rural backwater is about to be invaded by city folk.

Within two years, 25 kilometres of tunnel and bridge will link Chongming to the mainland for the first time. The island, now ...