Abstract: To improve the accuracy of estimating actual evapotranspiration of land surface in Wujiang River drainage basin under climate change, a model of estimating the actual evapotranspiration of the basin based on conventional meteorological data was established. The simulation results manifested that the relative error of the estimated evapotranspiration in Wujiang River drainage basin can be controlled within 5%. The components of the model can be simulated in distributed approach. The heterogeneity of land surface such as topography and land cover diversity was considered in the simulation. Moreover, the simulation results also demonstrated the spatial and temporal variations of the actual evapotranspiration in the basin more detailedly: in spatial scale, evapotranspiration was very low in the east of the basin and evidently high in the west; in temporal scale, the actual evapotranspiration displayed a trend of decreasing during 1961-2010 in a rate of 5.08 mm/(10 a), and an apparent rising trend after 2000. The increment of sunshine hours and relative humidity are main causes of the aforementioned changes. The research results could offer reference for water resources evaluation and agricultural climate zoning.

Key words: actual evapotranspiration, distributed modelling, complementary correlation, temporal and spatial changing trends, Wujiang River drainage basin