Abstract:

Evapotranspiration (ET) is a key component in hydrological cycle.Understanding of spatiotemporal variation of ET is of highly valuable to basinscale management of water resources and effective promotion of ecological services in the Poyang Lake Basin, China. This study applied the surface temperaturevegetation index triangle method to retrieve ET using the MOD erate resolution Imaging Spectroradiometer (MODIS) data over the Poyang Lake Basin for the period from 2000 to 2009.The retrieved ET was validated with in situ observation data and basinscale water balance approach.The results revealed the spatial and temporal variations in ET over the area. ET was higher for water surfaces and forestlands, but lower for agricultural fields and grasslands surrounded the Poyang Lake or located in the central basin. The annual ET was 795 mm on average over the basin for the period. The annual value was relatively higher for dry years including 2003,2004,2007 and 2009,with a range from 802 mm to 890 mm.In addition,the annual ET was subbasin dependent,ranging from 666 mm to 1031 mm.ET was higher in the Raohe and the Xiushui subbasin than the others,which was attributed to the high forest cover by more than 70% over the two subbasins.The ratio of annual ET to precipitation ranged from 04 to 07，indicating the water surplus with seasonal variation. Statistical analysis demonstrated that ET had a significantly positive relationship with net radiation and air temperature (P＜001).Seasonal ET showed negative pattern with precipitation,especially for a dry year