淮河流域参考作物蒸散量变化特征及主要气象因子的贡献分析

Variation of Reference Crop Evapotranspiration and Contribution of Main Factors in the Huaihe Basin

利用淮河流域171个站点1971-2010年的气象资料,采用FAO Penman-Monteith公式计算该区近40a的参考作物蒸散量(ET0),并对ET0的时空分布特征和影响因子进行定量分析。结果表明:淮河流域年ET0为898mm,近40a总体以17.5mm/10a的速率减小(P<0.05);空间分布显示西北部大部站点ET0呈显著下降趋势(P<0.05),仅东南部个别站点呈显著上升趋势(P<0.05)。各气象因子对ET0变化的贡献表现为两方面,即ET0对气象因子的敏感性和气象因子的多年相对变化率,在4个主要因子中(平均温度、相对湿度、日照时数和风速),ET0对相对湿度的变化最敏感(敏感系数最大),而风速的多年平均变化率最大。从各因子的贡献率看,对ET0贡献最大的是风速,平均温度的贡献最小,4个因子对ET0变化的总贡献率为-4.96%,总贡献率为负在很大程度上解释了ET0呈下降趋势的原因。

The reference crop evapotranspiration （ET0 ）in Huaihe basin was calculated based on observed data from 171 meteorological stations from 1971 to 2010 by using of FAO Penman-Monteith equation. The spatial and temporal distribution characteristics of ET0 and influencing factors were analyzed. The results showed that average ET0 in Huaihe basin was 898mm and decreased at the rate of 17.5mm/10y（ P 〈 0.05 ） in past 40 years. Most stations in northwest decreasedsignifieantly （ P 〈 0. 05 ） and seldom stations in southeast were increased significantly （ P 〈 0. 05 ） . The contribution to ET0 of the meteorological factors displayed in two aspects, which including sensitivity and relative change rate of the meteorological factors. The sensitivity analysis showed relative humidity was the most sensitive among the four main meteorological factors （average temperature, relative humidity, sunshine hours and wind speed ）, but the average wind speed changed most. Wind speed had large contribution to Eto, as average temperature was little. The total contribution of 4 factors to ET0 was -4.96, which meant decreased of ET0. The result was beneficial to evaluate agricultural water resources and take appropriate measures.