蒸散发是若尔盖高原湿地重要的水文过程,但目前缺乏对若尔盖地区实际蒸散发量的相关研究结果.为计算若尔盖高原实际蒸散量,利用1967—2011年若尔盖高原地区红原、玛曲和若尔盖3个地面气象站的逐日气象资料,应用FAO56推荐的Penman-Monteith(P-M)公式,依据单作物系数法计算若尔盖地区实际蒸散量,利用累积距平、Mann-Kendall趋势检验、回归分析等方法分析其变化规律.结果表明,草地蒸散量是若尔盖高原实际蒸散量的主要构成部分,草地蒸散量达362.3 mm·a-1,占74.28％.湿地蒸散量为116.6 mm·a-1,占23.85％;近45年来若尔盖高原3个气象站的ETc显著相关,ETc平均值为488.6 mm·a-1.ETc的变化并不明显,呈缓慢增加趋势,绝对变率为12.75 mm,相对变率为2.62％.若尔盖高原ETc变化与植被生长周期密切相关,高强度蒸散过程集中在短暂的夏季,7月份平均值达3.73 mm·d-1.4、10月份气温低于0℃,ETc为1.5～2.0 mm·d-1;通过回归分析得出ETc与气象因子间的关系式,相关系数r>0.9,P<0.05,相对误差均低于0.6％;年ETc与年均气温相关性达到0.01的显著性水平,年ETc与年降水量、相对湿度呈负相关性;1968—1971年ETc增加36.09 mm,相对降水量增加5.82％;1971—1981、1981—2005年ETc分别减少12.22 mm和16.34 mm;2005—2011年ETc增加41.75 mm,相对降水量增加6.41％.该地区水文过程中蒸散发相对于水分补给变化较小.%Evapotranspiration is an important hydrological process in the Zoige Plateau, but it lacks the results of the relevant studies on the actual evapotranspiration in this area. In order to calculate the actual evapotranspiration of the Zoige Plateau, the Penman-Monteith (P-M) formula recommended by FAO56 was used to select the single crop coefficient from the daily meteorological data of the three ground meteorological stations in Hongyuan, Maqu and Zoige from 1967 to 2011. Based on the single crop coefficient method, the actual evapotranspiration in the Zoige Plateau was calculated, and the change rule was analyzed by the method of cumulative anomaly, man-kendall trend test and regression analysis. The results showed that the evapotranspiration of grassland was the main component of the actual evapotranspiration of the Zoige Plateau. The evapotranspiration of grassland was 362.3 mm·a-1, accounting for 74.28％. The evapotranspiration of wetland was 116.6 mm·a-1, accounting for 23.85％. In the past 45 years, the ETc of the three weather stations was significantly correlated, and the mean ETc of the Zoige Plateau was 488.6 mm. Changes in ETc is not obvious; was slowly increasing trend. Absolute variability 12.75 mm, and the relative variability of ETc was2.62％. Changes of ETc in the Zoige Plateau was closely related to the plant growth stage. The high intensity evapotranspiration process was concentrated in the short summer. ETc reached a peak of 3.73 mm·d-1 in July. April and October temperature was below 0 ℃, decreased to 1.66 mm·d-1 and 1.52 mm·d-1. The expression of ETc equation was obtained by regression analysis, r>0.9, P<0.05, and the relative error was less than 0.6％. The correlation between ETc and annual mean temperature was 0.01, and the annual ETc was negatively correlated with annual precipitation and relative humidity. In the four stages, corresponding to 1968, 1971, 1981, 2005 and 2011, in the first stage ETc increased by 36.09 mm, increased by 5.82％ relative to annual precipitation. In the second and third stage ETc decreased by 12.22 mm and 16.34 mm, respectively. And the fourth stage ETc with an increase of 41.75 mm, increased by 6.41％ relative to annual precipitation. The variation of evapotranspiration in the hydrological processes of the region is not obvious.
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