This Envisat radar image features the Dongting Lake and the Yangtze River in south-central China. Dongting Lake (bottom centre) is China’s second largest freshwater body. The lake is fed from the north by the Yangtze (seen snaking across the top of the image) and from the south by the Zi (visible), Xiang, Yuan and Li rivers.

This image was created by combining three Envisat Advanced Synthetic Aperture Radar (ASAR) acquisitions taken over the same area, with colours representing changes that occurred in the surface between acquisitions. The various colours of blue show the variations in the lake’s total area. This ASAR image includes data acquired on 22 December 2002, 19 June 2005 and 19 April 2009.