Over two decades, dredging ships have sucked massive amounts of sand from the bed and shores of Poyang Lake in the eastern Chinese province of Jiangxi, drastically altering the ability of its ecosystem to function. Decades of mass urbanisation in China have fuelled demand for sand to make glass, concrete and other materials used in construction. The most desirable sand for industry comes from rivers and lakes rather than deserts and oceans. Much of the sand used to build the country’s megacities has come from Poyang, China’s largest freshwater lake. Reuters worked with Earthrise Media, a non-profit group that analyses satellite imagery, to map changes in the lake’s shoreline since 1997, giving an indication of how much sand has been removed. Poyang Lake is a main flood outlet for the Yangtze River, which overflows during summer and can cause extensive damage to crops and property. In winter, the lake’s water …