Temporal and spatial change of the potential evaporation over Qilian mountains and Hexi corridor from 1960 to 2006

Based on the daily data from 20 meteorological stations from 1960 to 2006 and the combination of the Penman-Monteith model,the change trend in potential evaporation (PE) over Qilian mountains and Hexi corridor is analyzed in this study.With the method of Spline under ArcGIS, the spatial distribution of PE is drawn in order to research the regional difference.And the multiple regression method is used to discuss the dominant factor affecting the PE.The results indicate that the annual PE is higher before 1980s than after,and experiences the process from the decrease before 1967 to the increase since then, and to decrease after 1974 to the increase after 1993.There is a decreasing trend in general because the change rate of the annual PE varies at-1.67 mm.The potential evaporation increases in autumn,however,decreases in other seasons,especially in spring.The wind speed is a dominant factor influencing PE.When autumn comes,the temperature becomes the key factor influencing PE.