Acta Geographica Sinica ›› 2009, Vol. 64 ›› Issue (3): 270-277.doi: 10.11821/xb200903002

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Comparison of Actual Evapotranspiration and Pan Evaporation

XIE Ping1,2, CHEN Xiaohong2, WANG Zhaoli3, XIE Yiwen2   

  1. 1. Agricultural College of Guangdong Ocean University,Zhanjiang 524088,Guangdong,China;
    2. Department of Water Resources and Environment,Sun Yat-sen University,Guangzhou 510275,China;
    3. School of Civil and Transportation Engineering,South China University of Technology,Guangzhou 510641,China
  • Received:2008-10-06 Revised:2008-12-05 Online:2009-03-25 Published:2009-03-25
  • Supported by:

    key Subjects of National Natural Science Foundation of China,No.50839005;Natural Science Foundation of Guangdong Ocean University,No. 0812073

Abstract:

Based on the climate and hydrological data of Dongjiang River Basin covering the period 1956-2003, the changes of actual evapotranspiration and pan evaporation and their relationship with climatic factors are analyzed to reveal the similarity and dissimilarity. The results show that there is a decreasing trend in both actual evapotranspiration and pan evaporation, with an insignificant decrease in the former while a significant decrease in the latter. Both of the minimum values of evaporation occur in the 1990s. There is an uncertain and weak negative correlation between actual evapotranspiration and pan evaporation. There is an uncertain relationship between air temperature and actual evapotranspiration and pan evaporation. Wind speed presents a positive correlation with pan evaporation, but an uncertain correlation with actual evapotranspiration. The change of rainfall results in the opposite changes with the two kinds of evapotranspiration, if one increases, the other one decreases. Sunlight radiation causes the opposite changes in trendline analysis and set pair analysis. Through climate patterns analysis, pan evaporation increases with radiation, and actual evapotranspiration increases first and then decreases. The pan evaporation is much more significant than the other climate patterns that the sunlight is more than normal, and the precipitation is less than normal. The actual evapotranspiration is much more than other climate patterns in climate patterns that the sunlight is at the medium level, and the precipitation is more than normal.

Key words: actual evapotranspiration, pan evaporation, climate factors, Dongjiang River Basin