Abstract: The water area in Dongting Lake is an important basis for studying on wetland ecosystem and flood regulation.To explore the trends and influencing factors of water area in Dongting Lake,the water area in Dongting Lake in different periods had been identified using EOS-MODIS data from 2001 to 2007,and the correlation between the change of water area in Dongting Lake,the water level in Chenglingji and the area-rainfall were analysed.The results showed that there was a significant correlation between the water area in Dongting Lake and the water level in Chenglingji,especially in the second half year;the water area in Dongting Lake is correlated to the antecedent area-rainfall of the Dongting Lake,and the change of water area is sensitive to area-rainfall in some past period and has well correlation with the rainfall of more than 100 days time scale;the water area in Dongting Lake has seasonal variation,which is 1200～2600 km2 in summer and 500～800 km2 in winter,and the area in summer is 2～5 times than that in winter;the water area decreased year by year,especially in winter,and the water area in Dongting Lake decreased 16.0 km2 each year on the same water level.

Key words: Dongting Lake, Remote sensing, Water area variations