中文摘要：

基于Penman-Monteith公式和Budyko假设,利用白洋淀流域1960年-2011年的气象、水文资料,计算分析了该流域潜在蒸散量与实际蒸散量的长期变化趋势,并初步分析了实际蒸散量变化与降水变化、潜在蒸散量变化的关系。结果表明：过去52年白洋淀流域潜在蒸散量和实际蒸散量分别以10.3mm/（10a）和11.6mm/（10a）的速度呈下降趋势;年代际变化分析表明,潜在蒸散量的下降趋势在不同年代际间具有持续性,而实际蒸散量则表现为波动下降,其波动性受降水波动的影响,年实际蒸散量的变化与年降水的变化呈正相关关系（R2=0.99）,与潜在蒸散量的变化呈负相关关系（R2=0.37）,即降水量的变化对实际蒸散量的变化起主要控制作用。

英文摘要：

Based on the meteorological and hydrological data of Baiyangdian basin during 1960-2011,the change trends of potential evapotranspiration（ET0）and actual evapotranspiration（ETa）and their relationship were studied by using Penman Monteith formula and Budyko hypothesis.Our results showed that both ET0 and ETapresented a decreasing trend and the decreasing rate were about 10.3mm/（10a）and 11.6mm/（10a）,respectively.Through the inter-decadal variation analysis,ET0 was characterized by a continuous decline,and ETawas characterized by fluctuate loss,which was influenced by precipitation volatility.The results of the correlation analysis showed that the change of ETa was positively correlated with the change of precipitation（R2=0.99）,and negatively correlated with the change of ET0（R2=0.37）.The precipitation was the main driving force for the reduction of ETa.