滇池流域多年ET_0及其影响因素变化趋势分析

分析滇池流域多年参考蒸腾蒸发量(Reference Evapotranspiration,ET_0)及其影响因素的变化趋势,为该流域水资源合理配置和作物需水规律研究提供一定的理论基础。采用联合国粮食及农业组织(FAO)推荐的彭曼-蒙蒂斯公式(Penman-Monteith)以及经验公式法Hargreaves(Har)和IrmarkAllen(Irm-All)计算了滇池流域昆明气象站近38年(1980—2017)的ET_0,研究多年ET_0的变化趋势和气象因素对其的影响。三种方法计算得出的年际平均ET_0整体变化均呈上升趋势,且Hargreaves公式计算的结果最为明显。采用线性趋势法、Mann-Kendall法和累积距平法对计算得出的ET_0进行趋势检验分析,表明彭曼-蒙蒂斯公式和Hargreaves公式计算的结果在2008年左右发生突变,IrmarkAllen公式在2012年和2016年分别发生了突变。对影响ET_0的气象要素变化趋势进行分析,相对湿度和平均最低气温多年变化呈下降趋势,日照时数、风速和平均最高气温均表现为上升趋势。通过相关分析,彭曼-蒙蒂斯公式与Hargreaves公式计算时对其影响最大的气象因素是日最高气温,影响Irmark-Allen公式计算结果的气象因素是平均气温。

Trend analysis of long series ET0 and influence factors in Dianchi basin

In order to get the rule of crop water requirements and optimization allocation of water resources in Dianchi district，this study analyzes the reference evapotranspiration( ET0 ) and the factors which have influence on the ET0. Penman-Monteithnmethod，recommended by Food and Agriculture Organization ( FAO) ，Hargreaves ( Har) method and Irmark-Allen ( Irm-All) method are selected to analyze ET0 of the past 38 years ( 1980 － 2017) . Based on the results，generally，it reflects that the annual average of ET0 by the above methods is on the rise，especially Hargreaves method. Moreover，linear trend method，Mann-Kendall method and cumulative anomaly method are selected to make trend test analysis of ET0. It shows that mutation occurred around 2008 based on the results of Penman-Monteith and Hargreaves method; while mutation occurs around 2012 and 2016，respectively，when Irmark-Allen is selected. Furthermore，the relative humidity and average minimum temperature show a downward trend; while the sunshine hours，wind speed and average maximum temperature show an upward trend，when analyzing the trend of meteorological factors affecting ET0. Based on the above analysis，the daily maximum temperature has the greatest influence on the result of Pennman-Monteith and Hargreaves，while the average temperature has the greatest influence on the result of Irmark-Allen.