湘江流域蒸发皿蒸发量的变化趋势及原因分析

Analysis of Pan Evaporation Trend and Its Influence Factors in Xiangjiang River Basin

利用1960—2006年湘江流域内44个气象观测站蒸发皿观测资料,采用气候倾向率、相关系数分析法,以及反距离权重插值来分析湘江流域蒸发皿蒸发量的时空变化特征及其影响因子。结果表明:湘江流域年蒸发皿蒸发量在47年间以21.29 mm/10a速率显著减少,通过了90%信度检验;且有75%的站点蒸发皿蒸发量下降趋势显著。从季节变化来看,蒸发皿蒸发量的下降趋势主要在夏季,以15.58 mm/10a的速率显著下降,并通过了99%信度检验。从空间分布来看,湘江流域蒸发皿蒸发量自西南向东北逐渐减少,且下游地区减少趋势最显著。流域饱和差的减小及风速的显著下降导致大部分站点蒸发皿蒸发量呈下降趋势。

With the data of observed monthly evaporation at 44 meteorological stations in Xiangjiang River basin from 1960 to 2006. Changes in pan evaporation and their causes are analyzed. The main results are as follows： pan evaporation decreased by 21.29 mm per 10 year （90% confidence level） in Xiangjiang River basin during the recent 47 years. Significant decrease of annual pan evaporation occurred at 75% of meteorological stations. As for the seasonal pan evaporation, especially in summer, it decreased by 15.58 mm per 10 year （99% confidence level）. Spatially, the pan evaporation declined from the southwest to the northeast, the significant decrease of pan evaporation occurred in the downstream. The decrease of pan evaporation is mainly attributed to the decrease of vapor pressure deficit and the significant decrease of wind speed at most of the meteorological stations in Xiangjiang River basin.