中文摘要：

利用东江流域1961～2003年的气象资料，对参考作物腾发量和蒸发皿蒸发量的变化特征及变化原因进行分析．结果表明：参考作物腾发量与蒸发皿蒸发量都有减少的趋势，参考作物腾发量减少的趋势不显著．蒸发皿蒸发量减少的趋势显著．蒸发皿系数有显著增加的趋势；参考作物腾发量、蒸发皿蒸发量在全流域的空间分布相似，都是南部大北部小，蒸发皿系数的空间分布是北部大南部小；平均温度、日照时数、风速与参考作物腾发量、蒸发皿蒸发量的偏相关系数都为正一目对湿度都为负；日照时数对参考作物腾发量、蒸发皿蒸发量的影响程度都最大，且远大于其它因子．这种效应在夏季表现更突出．温度对参考作物腾发量的影响程度比蒸发皿蒸发量大；参考作物腾发量与蒸发皿蒸发量都有减少趋势的原因首先是日照时数的减小，再是风速的减小；参考作物腾发量与蒸发皿蒸的趋势显著性有差异的原因是温度的增加对参考作物腾发量的影响程度比蒸发Ⅲ蒸发量大。

英文摘要：

The change of reference evapotranspiration and pan evaporation and its causes over Dongjiang river basin are analyzed from 1961 to 2003. The results show that there is a decreasing trend in both the reference evapotranspiration and pan evaporation, the decrease of reference evapotranspiration is not signif- icant, the decrease of pan evaporation is significant, there is significant increasing trend in the pan coeffi- cient. The spatial distribution of reference evapotranspiration and pan evapotranspiration are roughly simi- lar, the values are high in south, are low in north. The spatial distribution of pan coefficient is opposite. The partial related coefficient of temperature, sunshine time, wind speed and reference evapotranspiration and pan evaporation are positive, that of relative humidity is negative. The effect degree of sunshine time on reference evapolranspiration and pan evaporation are great, is much larger than the others, especially in summer. The effect degree of temperature on reference evapotranspiration are larger than on pan evapora- tion, The first reason of the decreasing trend in both the reference evapotranspiration and pan evaporation are the decrease of sunshine time, the second are the decrease of wind speed. The reason of significance difference of the decrease of reference evapotranspiration and pan evaporation is that the effect degree of temperature on reference evapotranspiration is larger than on pan evaporation.